This page shows what was measured, who it was measured in, and what that does not settle.
What Terbinafine does in the body
Fungal nail infection, athlete’s foot and ringworm
Fungi build their cell membranes out of ergosterol, and the first step is an enzyme that adds oxygen to a molecule called squalene. Terbinafine jams that enzyme. Two things then go wrong at once: the fungus runs out of the material its membrane is made of, and squalene piles up inside the cell to the point where it dissolves the membrane from within. That second effect is why terbinafine kills the fungus rather than merely stopping its growth, which is the difference between it and the azoles. Human cells use a related enzyme for cholesterol, but the fungal one is about a thousand times more sensitive.
What happened in people
Clinical cure six times as likely as placebo (RR 6.00, 95% CI 3.96 to 9.08) on high-quality evidence across 1,006 participants
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The recorded finding that sits closest to something a person would notice. Written into the record, not signed off, and it carries no population or interval.
That a 70% cure rate means a normal-looking nail in 70% of people — the label’s figure for that is 38%
Where it acts
The fungal cell membrane, in the nail bed and the keratinised layers of skin where the dermatophyte lives
Kind of result
The kind of result is not recorded
Supervision
RNAWiki has not recorded a supervision or regulatory status for this substance.
What the registries record it as
Its recorded molecular formula is C21H26ClN, weighing 327.90.
US prescribing information · ab6f50a5-87ce-0819-e053-2a95a90a22b7 · read 2026-08-30
Where each sentence above came from
No recorded sentence describes the change this makes in a way that stands on its own. The page opens with what it is taken for instead, and the recorded explanation follows below.
Shown as the opening line on this page.
A limit recorded against this substance. Not signed off as a reviewed claim.
The four opening statements run to 140 words.
Words this page uses
Four words worth knowing first
Chosen from what this page shows, with each one explained before the word it depends on.
Comparator
A comparator is whatever the treatment was measured against.
A picture of it, and where the picture fails
It is like the other runner in a race.
Where that stops being true. A race has one winner. A study can show both arms improved.
What people get wrong. Results are read without asking what the other group got. Beating nothing is not beating a treatment.
The control condition against which the experimental intervention is assessed.
Randomisation
Randomisation means chance decides who gets which treatment.
A picture of it, and where the picture fails
It is like a coin toss deciding the groups.
Where that stops being true. A coin toss is fair once. Fairness here comes from doing it for everyone.
What people get wrong. It is thought to make groups identical. It makes them similar on average, including on things nobody measured.
Allocation of participants to arms by a chance process, so that unmeasured factors are balanced in expectation.
Absolute difference
An absolute difference is how many more people in a hundred were affected.
A picture of it, and where the picture fails
It is like counting heads in two rooms of a hundred.
Where that stops being true. Heads are easy to count. Study results carry a margin of error too.
What people get wrong. It is confused with a percentage change, which can look far larger.
The arithmetic difference in event rates between arms.
Confidence interval
A confidence interval is the range the true answer is likely to sit in.
A picture of it, and where the picture fails
It is like a weather forecast giving a range rather than one number.
Where that stops being true. A forecast range covers tomorrow. This one covers what the study could resolve.
What people get wrong. The middle number is read as the answer. A range crossing zero means no change is still possible.
An interval estimate that would contain the true parameter in a stated proportion of repeated studies.
What happened in people◇Read from sources, not yet reviewed
What happened in people
Each card is one study: the exact question it asked, who was in it, and whether it showed what it set out to show.
Mycological cure of the target toenail at week 72, negative microscopy plus negative culture
75.7% (81/107) and 80.8% (80/99) on terbinafine against 38.3% (41/107) and 49.1% (53/108) on intermittent itraconazole; all four pairwise comparisons P<0.0001
Repeated elsewhere
Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. The comparator used an intermittent schedule while terbinafine was continuous, which flatters the difference. Mycological cure is a laboratory endpoint; the trial’s clinical outcomes also favoured terbinafine but the nail-appearance gap seen on the label applies here too.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablets and granules; topical cream, gel, solution and spray sold over the counter
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Clinical cure and mycological cure against placebo
✓ The study showed what it set out to show
Who was studied
Cochrane pooled terbinafine against placebo (CD010031)
How many people
1006
Study design
Systematic review and meta-analysis of randomised controlled trials
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Clinical cure RR 6.00 (95% CI 3.96 to 9.08) and mycological cure RR 4.53 (95% CI 2.47 to 8.33), 8 studies, high-quality evidence
Repeated elsewhere
Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. Of 48 studies in the full review, one was at low risk of bias in all domains and 18 at high risk in at least one, most often blinding of personnel and participants.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablets and granules; topical cream, gel, solution and spray sold over the counter
Interval reported. 95% CI 3
Written into the record, not signed off as a reviewed claim.
Recurrence of onychomycosis after treatment against placebo
✓ The study showed what it set out to show
Who was studied
Cochrane pooled recurrence, terbinafine against placebo (CD010031)
How many people
35
Study design
Single randomised trial within the systematic review
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
RR 0.05 (95% CI 0.01 to 0.38), 1 study, low-quality evidence
Repeated elsewhere
Unreplicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. Thirty-five participants, one study, low-quality evidence, for the outcome that determines whether the course was worth taking. The confidence interval spans nearly an order of magnitude.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablets and granules; topical cream, gel, solution and spray sold over the counter
Interval reported. 95% CI 0
Written into the record, not signed off as a reviewed claim.
RNAWiki holds 4 written-up human studies for this substance, each with the question it asked.
How we know it
Each card names the study, the number of people and what the study set out to measure.
What this does not prove
These summaries were written by a person and have not been signed off as reviewed claims.
Why it matters
A study that failed is as informative as one that worked, and both are here.
What we still do not know
No reviewed claim exists, so no exact population, effect size or interval is published yet.
What it changes in the body◇Read from sources, not yet reviewed
The path through the body
From what a person takes to what changes. A solid line is a step measured in people. A dashed line is a step nobody has measured that way.
Where a source records it acting
Skin: Distributed to the sebum and skin, with a long terminal half-life that may represent slow elimination from tissues such as skin and adipose
US prescribing information · 085e0809-6b7f-447e-976e-8276c29daad6 · read 2026-08-28
Start
Terbinafine
What a person takes: Oral tablets and granules; topical cream, gel, solution and spray sold over the counter.
The measurement behind this step
The tablets are absorbed and concentrate in keratin — nail, stratum corneum and sebum — where they persist for weeks after the course ends, which is why a twelve-week course is assessed at week 48. The topical forms treat skin infections only: the Cochrane review notes that topical treatments traditionally have low success rates in nail disease because of the physical properties of the nail plate.
Getting in
Swallowed, then parked in keratin
The drug is absorbed and then collects in exactly the tissues the fungus lives in — nail, skin and the oily layer on it — and stays there for weeks after the last tablet.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
Terbinafine is highly lipophilic and binds keratin avidly. It reaches the nail through both the matrix and the nail bed and persists in nail plate long after plasma concentrations fall, which is why a 12-week course is assessed at week 48 and why the mean time to success is around 10 months.
Fungi make their cell membranes from a molecule called ergosterol. Terbinafine jams the very first enzyme in that assembly line.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Non-competitive inhibition of fungal squalene epoxidase, the enzyme that epoxidises squalene to 2,3-oxidosqualene at the committed step of ergosterol biosynthesis. Inhibition occurs at nanomolar concentrations, roughly a thousandfold below what is needed against the mammalian enzyme.
Two things go wrong at once. The fungus cannot finish its membrane, and the unused raw material builds up until it dissolves the membrane from inside. That second effect is what kills it.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Ergosterol depletion is fungistatic on its own; the fungicidal effect comes from intracellular squalene accumulation, which disrupts membrane organisation and lipid storage. This dual mechanism is the structural reason allylamines kill dermatophytes where azoles, which act further down the same pathway, largely inhibit them.
Killing the fungus does not repair the nail. The damaged nail has to grow off the end of the finger or toe, which takes about a year on a toenail.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
This is why the primary endpoint in LION was assessed at week 72 after 12 or 16 weeks of treatment, and why the label’s trial was read at week 48. Mycological cure and clinical cure are separated in time by the growth rate of the nail plate, not by the pharmacology.
Unless the fungus is one that has changed the enzyme
A species that spread out of South Asia carries changes in the exact enzyme this drug blocks. The drug still reaches it and no longer works on it.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Trichophyton indotineae carries squalene epoxidase substitutions, principally Leu393Phe and Phe397Leu, that reduce terbinafine binding. The species cannot be reliably distinguished from Trichophyton mentagrophytes by culture morphology, so identification requires molecular methods, and the first reported United States cases date from New York City between December 2021 and March 2023.
Every headline figure for this drug is a laboratory result. Whether the nail ends up looking normal is a different number and it is close to half the size. Whether the infection stays away is a third number, and it comes from thirty-five people.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
Label figures from the same trial: mycological cure 70%, effective treatment 59%, mycological plus clinical cure 38%. Recurrence against placebo: RR 0.05 (95% CI 0.01 to 0.38) from a single 35-participant study, graded low-quality by Cochrane.
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 6 steps from taking it to an effect in a person.
How we know it
Each step names the study behind it in the technical detail beside it.
What this does not prove
A change inside the body is a reason to look. It is not a result in a person.
Why it matters
A reader can see exactly where the chain stops being measured in people.
What we still do not know
No reviewed claim binds any of these steps to a named population.
What is missing or unclear◇Read from sources, not yet reviewed
Were people like you studied?
RNAWiki cannot tell whether a study fits you. It can show who was in it, and where the result stops carrying.
Who was studied
People similar to this profile were included.
People with laboratory-confirmed dermatophyte nail infection for the tablets, and people with athlete’s foot or ringworm for the cream, which is sold without prescription.
Who is missing from the studies
Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What the label states about particular groups
On pediatric, the label states: “The safety and efficacy of Terbinafine tablets have not been established in pediatric patients with onychomycosis.”
US prescribing information · ab6f50a5-87ce-0819-e053-2a95a90a22b7 · read 2026-08-30
On older people, the label states: “Clinical studies of Terbinafine tablets did not include sufficient numbers of subjects aged 65 years and over to determine whether they respond differently from younger subjects.”
US prescribing information · ab6f50a5-87ce-0819-e053-2a95a90a22b7 · read 2026-08-30
On people who are pregnant, the label states: “Risk Summary Available data from postmarketing cases on the use of Terbinafine Tablets in pregnant women are insufficient to evaluate a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes.”
US prescribing information · ab6f50a5-87ce-0819-e053-2a95a90a22b7 · read 2026-08-30
On people who are breastfeeding, the label states: “Risk Summary After oral administration, terbinafine is present in human milk.”
US prescribing information · ab6f50a5-87ce-0819-e053-2a95a90a22b7 · read 2026-08-30
On people with reduced liver function, the label states: “Terbinafine tablets are contraindicated for patients with chronic or active liver disease [see Contraindications (4) and Warnings and Precautions (5.1) ] .”
US prescribing information · ab6f50a5-87ce-0819-e053-2a95a90a22b7 · read 2026-08-30
On people with reduced kidney function, the label states: “In patients with renal impairment (creatinine clearance less than or equal to 50 mL/min), the use of Terbinafine tablets has not been adequately studied.”
US prescribing information · ab6f50a5-87ce-0819-e053-2a95a90a22b7 · read 2026-08-30
Where the result stopped carrying
Clinical cure — a nail with no involvement at all — was reached by 38% of patients against 70% mycological cure in the same trial
Mean time to overall success was approximately 10 months for toenails, after a 12-week course
Postmarketing surveillance added liver failure, permanent taste and smell loss, depression, severe neutropenia and DRESS, none visible in the trials
Against Trichophyton indotineae the drug is now poorly effective, and no successor allylamine is in development
This is a scope explorer, not a diagnosis engine.
It shows who was studied so you can see whether people similar to you were included.
RNAWiki cannot tell whether a study fits you. It can show who was in it.
What it would be like to take◇Read from sources, not yet reviewed
Why it might seem to do nothing
A real effect and a noticed effect are different things. These are the recorded reasons the two come apart.
It was studied in different people
The people in the studies were not much like the reader.
On this record: Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
There was nothing to correct
Where a level is already normal, topping it up may change nothing.
On this record: Still the first-line oral treatment for dermatophyte nail infection, with laboratory confirmation required before starting
The evidence may simply be wrong
Small early studies often do not hold up.
On this record: RNAWiki has not yet published a reviewed conclusion for this use.
Other reasons RNAWiki checked and found nothing for (10)
It was studied for a different goal
The studies measured something else entirely. Nothing in this record points to this reason.
A different form was studied
The studied form is not the form on the shelf. Nothing in this record points to this reason.
Something else had to happen too
In the studies it was paired with training, a diet or another treatment. Nothing in this record points to this reason.
The change is too small to feel
A real change can still sit below what a person notices. Nothing in this record points to this reason.
Day-to-day swing hides it
Sleep, food, stress and time of day move most numbers more than this would. Nothing in this record points to this reason.
Not enough time yet
The studies ran longer than the person has waited. Nothing in this record points to this reason.
It was not taken as studied
Missed days change the result, and studies count them. Nothing in this record points to this reason.
Something else changed at the same time
Two changes at once cannot be told apart afterwards. Nothing in this record points to this reason.
The product may not be what it says
Contents of a sold product are not always what the label states. Nothing in this record points to this reason.
No recorded reason
RNAWiki has nothing stored that would explain it. Nothing in this record points to this reason.
None of these is a reason to take more. Taking more is not a step this page ever suggests.
What it would be like to take◇Read from sources, not yet reviewed
What taking it involves
The recorded facts about getting hold of it and using it. Nothing here is a suggestion about what you should do.
How it is supplied
Prescription only
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Read from the recorded approval status.
No source is stored against this line.
Form and route
Oral tablets and granules; topical cream, gel, solution and spray sold over the counter
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form and route recorded on this substance.
No source is stored against this line.
Who oversees it
RNAWiki has not recorded a supervision or regulatory status for this substance.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
No register row and no identity class settled the question.
No source is stored against this line.
What is in the pack
The tablets are absorbed and concentrate in keratin — nail, stratum corneum and sebum — where they persist for weeks after the course ends, which is why a twelve-week course is assessed at week 48.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on how this is sold. The rest of the recorded wording: The topical forms treat skin infections only: the Cochrane review notes that topical treatments traditionally have low success rates in nail disease because of the physical properties of the nail plate.
No source is stored against this line.
Where it is registered
Regulatory records are listed in the technical disclosure at the foot of this page.
# Counted from records
Where this came from
A count of rows RNAWiki holds. It describes our records, not your body.
Register entries are stored per jurisdiction and shown with their dates.
No source is stored against this line.
Why people stop
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
No record of why people stopped taking it is stored for this substance.
No source is stored against this line.
What it would be like to take◇Read from sources, not yet reviewed
What can go wrong
Sorted by where each line came from. A regulator's label and a report somebody sent in are not the same kind of fact.
·Worth asking a clinician aboutWritten into the record from the studies named on this page
Contraindicated in chronic or active liver disease. Liver failure, sometimes leading to transplant or death, has occurred; the label directs pretreatment serum transaminases and periodic liver function testing, with discontinuation if injury develops. Taste disturbance including complete taste loss can be severe, prolonged or permanent, as can smell disturbance; both are grounds for stopping. Depressive symptoms, severe neutropenia and severe cutaneous adverse reactions including Stevens-Johnson syndrome, toxic epidermal necrolysis and DRESS are also listed. In the pooled randomised trials, overall adverse event risk did not differ significantly from placebo (RR 1.13, 95% CI 0.87 to 1.47) — the pattern expected when the serious harms are rarer than a trial can detect.
Nobody counted how many people took this and were fine, so this cannot be turned into a rate.
Over a long time. No completed tested study window is recorded, so long-term effects are not established by the registry record.
Groups the studies covered thinly. Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What is missing or unclear◇Read from sources, not yet reviewed
Does the exact form matter?
Evidence belongs to the exact thing that was tested. A different salt, a different mixture or a different preparation is a different question.
The form that was studied
Oral tablets and granules; topical cream, gel, solution and spray sold over the counter
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form used in the studies cited on this page.
No source is stored against this line.
What is sold
A recorded note compares this form with the others that are sold. It is kept below, word for word.
§ A fixed RNAWiki sentence
Where this came from
Wording RNAWiki always uses, not a finding about this substance.
The recorded note, unchanged: The topical forms treat skin infections only: the Cochrane review notes that topical treatments traditionally have low success rates in nail disease because of the physical properties of the nail plate.
No source is stored against this line.
What is recorded as being sold
107 products list this as an active ingredient in the United States drug directory. 105 of them contain it and nothing else.
FDA National Drug Code directory · 73469-7215 · read 2026-08-29
They are sold as cream, liquid, powder, spray and tablet, taken oral and topical.
FDA National Drug Code directory · 73469-7215 · read 2026-08-29
The regulator's established pharmacologic class for it is allylamine antifungal [epc] and allylamine [cs].
FDA National Drug Code directory · 73469-7215 · read 2026-08-29
78 published labels name it as an active ingredient. 76 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · ab6f50a5-87ce-0819-e053-2a95a90a22b7 · read 2026-08-29
Those labels are classed as human otc drug and human prescription drug.
US prescribing information · ab6f50a5-87ce-0819-e053-2a95a90a22b7 · read 2026-08-29
Terbinafine is uncoated tablets at Tablet, 250 mg, recorded as prescription product; fda label in effect 2025-09-30 in the United States.
US prescribing information · 085e0809-6b7f-447e-976e-8276c29daad6 · read 2026-08-28
Recorded price in US: 0.1356 USD per one unit as the pricing file counts it — a tablet, capsule, patch or single item, across 14 priced products whose strengths and pack forms differ, as of 2026-08-26, paid by retail pharmacies buying the product, as surveyed by the Centers for Medicare & Medicaid Services. It is not a list price, an insurance price, or what anyone pays at a counter..
Recorded source · 2026-08-26 · read 2026-08-28
Recorded price in US: 0.23063–0.39832 USD per one gram, across 4 priced products whose strengths and pack forms differ, as of 2026-08-26, paid by retail pharmacies buying the product, as surveyed by the Centers for Medicare & Medicaid Services. It is not a list price, an insurance price, or what anyone pays at a counter..
Recorded source · 2026-08-26 · read 2026-08-28
Evidence carries across two names for one substance. It does not carry across a salt, a mirror form or a mixture.
What it would be like to take◇Read from sources, not yet reviewed
What you could measure
This one is decided with a clinician, so this section holds questions to ask rather than a plan to run.
RNAWiki could not confidently classify this substance, so no self-experiment plan is offered.
Questions worth asking
Which of the trials of Terbinafine studied people like me?
What was measured, and for how long?
Was the result a laboratory value or a health outcome?
What would we watch for, and when would we stop?
Tracking can show whether something changed for you. It cannot show what caused it.
RNAWiki records evidence. It does not say whether this substance is right for you.
What is missing or unclear◇Read from sources, not yet reviewed
Claims that go past the evidence
Things said about this substance that sound reasonable, and the exact step that is missing between the evidence and the claim.
✗Goes past the evidence
That a 70% cure rate means a normal-looking nail in 70% of people — the label’s figure for that is 38%
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That terbinafine durably prevents recurrence, an inference resting on 35 participants in one low-quality study
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That the head-to-head advantage over the azoles is a stable property, when it was measured before the resistant species existed
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That the pooled adverse event risk ratio of 1.13 describes the drug’s safety, when the harms that matter are too rare for a 1,000-person trial to see
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
What is missing or unclear◇Read from sources, not yet reviewed
What nobody knows yet
Open questions, each with why it is open and what would close it.
Missing populations
Which groups were under-represented in the studies has not been recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing long-term data
No completed tested study window is recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
No reviewed conclusion
RNAWiki has not yet published a reviewed conclusion for this use.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing interaction studies
No interaction was found in the registers checked. Not finding one is not the same as showing there is none.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Formulation uncertainty
Several salts, forms or products of Terbinafine are recorded. Results from one form may not transfer to another.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Mechanism not reviewed
No reviewed mechanism story exists for this substance.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
What happened in people◇Read from sources, not yet reviewed
Check any of this yourself
Every line above traced back to the study it came from. This is the technical layer, and the vocabulary changes here.
Every line above can be traced to the study named beside it. Follow the link and read it.
High-quality evidence, six times the clinical cure rate of placebo
In plain words
Cochrane graded the evidence for this drug against placebo as high quality, which is rare in dermatology. Across eight trials in a thousand people, clinical cure was six times as likely on terbinafine, and side effects were no more common.
What was measured
Risk ratio for clinical and mycological cure against placebo, pooled across 8 randomised trials
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The 2017 Cochrane review included 48 studies in 10,200 participants. It found high-quality evidence that terbinafine is more effective than placebo for clinical cure (RR 6.00, 95% CI 3.96 to 9.08; 8 studies, 1,006 participants) and for mycological cure (RR 4.53, 95% CI 2.47 to 8.33; same 8 studies). Adverse events among terbinafine-treated participants included gastrointestinal symptoms, infections and headache, with probably no significant difference in risk between groups (RR 1.13, 95% CI 0.87 to 1.47; 4 studies, 399 participants, moderate-quality evidence). One study was at low risk of bias in all domains and 18 were at high risk in at least one, most commonly blinding of personnel and participants.
Written into the record, not signed off as a reviewed claim
LION: it doubled the cure rate of the drug it was compared against
In plain words
Nearly five hundred patients in six countries were randomised to terbinafine or to intermittent itraconazole and followed for seventy-two weeks. Around four in five terbinafine patients were culture-negative at the end. Around two in five itraconazole patients were.
What was measured
Mycological cure at week 72, negative microscopy plus negative culture, four randomised arms
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The LION study was a prospective, randomised, double-blind, double-dummy, multicentre parallel-group study over 72 weeks at 35 centres in six European countries, in 496 patients aged 18 to 75 with clinically and mycologically confirmed dermatophyte toenail onychomycosis. Four arms received terbinafine for 12 or 16 weeks or intermittent itraconazole for 12 or 16 weeks. The primary endpoint at week 72 was mycological cure, defined as negative microscopy and negative culture from the target toenail: 75.7% (81/107) and 80.8% (80/99) on the terbinafine arms against 38.3% (41/107) and 49.1% (53/108) on the itraconazole arms, every pairwise comparison P<0.0001. All secondary clinical outcomes favoured terbinafine at week 72, and there were no differences in the number or type of adverse events between the drugs.
Written into the record, not signed off as a reviewed claim
70% cure, 38% normal nail — both printed on the same label
In plain words
The label reports three numbers from one trial. Seventy per cent of patients had no fungus left. Fifty-nine per cent had no fungus and some clear new nail. Thirty-eight per cent had a nail with no involvement at all. The number people remember is the first one.
What was measured
Mycological cure 70%, effective treatment 59%, mycological plus clinical cure 38%, same trial, week 48
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
The terbinafine tablets label reports the first United States and Canadian placebo-controlled toenail trial assessed at week 48, after 12 weeks of treatment and 36 weeks of follow-up: mycological cure, defined as simultaneous negative KOH and negative culture, in 70% of subjects; effective treatment, defined as mycological cure plus zero per cent nail involvement or more than 5 mm of new unaffected nail growth, in 59%; and mycological cure plus clinical cure, defined as zero per cent nail involvement, in 38%. Mean time to overall success was approximately 10 months. In the fingernail trial at week 24, the corresponding figures were 79%, 75% and 59%, with a mean time to success of about 4 months. The gap between the first and third numbers is the gap between killing the fungus and restoring the nail, and the second is a composite that sits between them.
Source
Terbinafine tablets United States prescribing information, section 14 Clinical Studies (ANDA 078297, openFDA label endpoint)
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
caution
Review state
Written into the record, not signed off as a reviewed claim
Liver failure, permanent loss of taste and smell, for a nail
In plain words
The Warnings section lists liver failure leading to transplant or death, taste loss that may be permanent, smell loss that may be permanent, depression, severe drops in white cells, and life-threatening skin reactions. The condition being treated is a discoloured nail.
What was measured
Regulatory warnings from postmarketing surveillance, against a pooled trial adverse event risk ratio of 1.13 (95% CI 0.87 to 1.47)
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
The label directs obtaining pretreatment serum transaminases, assessing liver function before and periodically during therapy, and discontinuing if liver injury develops; the tablets are contraindicated in chronic or active liver disease. Taste disturbance including taste loss can be severe, prolonged or permanent, and smell disturbance may also be prolonged or permanent; both are grounds for discontinuation. The label further lists depressive symptoms, severe neutropenia with discontinuation at a neutrophil count of 1,000 cells/mm3 or below, and Stevens-Johnson syndrome, toxic epidermal necrolysis, erythema multiforme, exfoliative dermatitis, bullous dermatitis and DRESS. The Cochrane review separately found probably no significant difference in overall adverse event risk against placebo (RR 1.13, 95% CI 0.87 to 1.47), which is the expected pattern for rare severe harms: trials of a thousand people cannot detect them and postmarketing surveillance can.
Written into the record, not signed off as a reviewed claim
A resistant dermatophyte that did not have a name until 2020
In plain words
For thirty years terbinafine was the reliable answer to ringworm and nail fungus. A new species that carries mutations in the exact enzyme terbinafine blocks spread out of South Asia, and the first United States cases were reported from New York in 2023.
What was measured
That the head-to-head ranking of terbinafine over the azoles is a stable fact — it was measured against the dermatophytes circulating in 1990s Europe, and a species carrying squalene epoxidase mutations inverts it
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Trichophyton indotineae is a recently named species within the T. mentagrophytes complex, distinguishable from its close relatives only by molecular methods, and usually responding poorly to terbinafine. The reduced susceptibility is attributed to point substitutions in the squalene epoxidase gene, principally Leu393Phe and Phe397Leu, which alter the drug binding site. The first reported United States cases were described in Notes from the Field covering New York City between December 2021 and March 2023. Most cases outside South Asia are linked to international travel, with mounting evidence of local person-to-person and animal-to-human transmission. Fluconazole and griseofulvin are generally not effective against it. Because terbinafine is decades off patent and no successor allylamine is in development, the field’s response has been to fall back on the drug class terbinafine displaced.
Written into the record, not signed off as a reviewed claim
The durability claim rests on thirty-five people
In plain words
Nail infections come back. The pooled evidence that terbinafine reduces recurrence compared with placebo comes from a single trial of thirty-five patients, and Cochrane rates it low quality.
What was measured
That terbinafine durably prevents recurrence of nail infection — pooled from a single 35-participant study graded low quality, for the outcome that matters most
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The Cochrane review states that terbinafine and azoles may lower the recurrence rate when compared individually with placebo — terbinafine RR 0.05 (95% CI 0.01 to 0.38) from 1 study in 35 participants, azoles RR 0.55 (95% CI 0.29 to 1.07) from 1 study in 26 participants — both graded low-quality evidence. A point estimate of 0.05 from 35 people with a confidence interval spanning nearly an order of magnitude is not a number to plan around. Recurrence is the outcome that determines whether a twelve-week course of a hepatotoxic drug was worth taking, and it is the outcome with the least evidence behind it in the entire review.
Written into the record, not signed off as a reviewed claim
It beat the azoles head to head, on both definitions of cure
In plain words
Across fifteen to seventeen trials in more than two thousand patients each, terbinafine cured more people than the azole drugs did, on both the laboratory measure and the appearance measure, with no difference in side effects.
What was measured
Risk ratios for clinical and mycological cure, terbinafine against azoles, pooled across 15 and 17 trials
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Moderate-quality evidence that terbinafine was probably more effective than azoles for clinical cure (RR 0.82, 95% CI 0.72 to 0.95; 15 studies, 2,168 participants) and for mycological cure (RR 0.77, 95% CI 0.68 to 0.88; 17 studies, 2,544 participants), with the risk ratios expressed for the azole arms. There was probably no difference in adverse event risk between the two classes (RR 1.00, 95% CI 0.86 to 1.17; 9 studies, 1,762 participants, moderate-quality evidence). The LION study is the largest single contributor to that ordering and it used an intermittent itraconazole schedule, which is one reason the pooled advantage is smaller than LION’s alone.
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What is not here
7 questions this page could not answer
These sections were prepared and left out because there was nothing to put in them. They are listed rather than hidden, so the gaps in this record are visible.
What was measured, goal by goal — found nothing in the sources checked.
How close this is to real life — found nothing in the sources checked.
Felt, measured, or meaningful — found nothing in the sources checked.
How long anything takes — found nothing in the sources checked.
What it may clash with — found nothing in the sources checked.
Other ways to the same goal — found nothing in the sources checked.
What changed on this page — found nothing in the sources checked.
The record as stored
The full record, for auditing
Everything above is built from what is below. This layer keeps the technical vocabulary, record identifiers and every stored row, so a reader who wants to check the page can.
The older medicine-wide conclusion held in this record
Written for a clinical reader, and about the medicine as a whole rather than about one indication, population and set of trials. RNAWiki does not treat it as a programme conclusion and no reviewer has signed it off in that form. It is here word for word because it is what the record holds.
An allylamine that blocks squalene epoxidase so the fungus can neither make its membrane nor stop making squalene, killing it outright — six times as likely as placebo to produce clinical cure across 1,006 randomised patients on high-quality evidence, better than every azole compared with it, and printing 70% mycological cure against 38% normal-looking nails on the same page of its own label.
Recorded evidence blocks (10)
Q1
On the Terbinafine label: indicated for what?
"Terbinafine tablets are indicated for the treatment of onychomycosis of the toenail or fingernail due to dermatophytes (tinea unguium). Prior to initiating treatment, appropriate nail specimens for laboratory testing [potassium hydroxide (KOH) preparation, fungal culture, or nail biopsy] should be obtained to confirm…": indications and usage on Terbinafine's label. DailyMed label · 584d1fae-0120-49a0-e063-6394a90a36fc · 2026-08-05
Q2
45 registered trials of Terbinafine — at which phases?
Registered studies posting no result
35 of 45
45 registered studies of Terbinafine: 14 phase2, 11 phase1, 11 phase3, 6 na, 3 phase4, 2 na or unstated, 1 early phase1. CLINICALTRIALS_SNAPSHOT · 2026-09-01
"Study stopped due to poor recruitment."; 1 of 45 registered studies
Show the evidence
TrialNCT05119712
withdrawn; "Study stopped due to poor recruitment."
recorded 2026-09-01 · last checked 2026-09-04
Q4
Human studies of Terbinafine used Terbinafine Hydrochloride Tablets 250 mg — over how long?
Human studies of Terbinafine used "Terbinafine Hydrochloride Tablets 250 mg". ClinicalTrials.gov · 2026-09-01
9 recorded entries; human; tablet; also "Lamisil® Tablets 250 mg", "Lamisil® Cream, 1%", "Lamisil, 250mg tablet"
Show the evidence
human
NCT00647647
Terbinafine Hydrochloride Tablets 250 mg
NCT00647647
Lamisil® Tablets 250 mg
NCT00691184
Lamisil® Cream, 1%
NCT00691184
tablet; Lamisil, 250mg tablet
NCT00833586
Terbinafine HCl 250mg tablets
NCT00833586
Lamisil® 250 mg Tablets
3 more recorded rows
humanNCT01286688
Terbinafine Hydrochloride Tablets, 250 mg
humanNCT01772212
Terbinafine 250 mg
humanNCT03999437
TERBINAFINE HYDROCHLORIDE (1%)
recorded 2026-09-01 · last checked 2026-09-04
Q5
Terbinafine's half-life is 36 hours — which schedules were studied?
36 hours, the half-life Terbinafine's label states: "At steady-state, in comparison to a single dose, the peak concentration of terbinafine is 25% higher and plasma AUC increases by a factor of 2.5; the increase in plasma AUC is consistent with an effective half-life of ~36 hours.Terbinafine is distributed to the sebum and skin." DailyMed label · 584d1fae-0120-49a0-e063-6394a90a36fc · 2026-08-05
tmax 2 hours; bioavailability 70 %.
Show the evidence
half lifepharmacokinetics
36 hours; At steady-state, in comparison to a single dose, the peak concentration of terbinafine is 25% higher and plasma AUC increases by a factor of 2.5; the increase in plasma AUC is consistent with an effective half-life of ~36 hours.Terbinafine is distributed to the sebum and skin.
tmaxpharmacokinetics
2 hours; Peak plasma concentrations of 1 mcg/mL appear within 2 hours after a single 250 mg dose; the AUC is approximately 4.56 mcg•h/mL.
bioavailabilitypharmacokinetics
70 %; Following oral administration, terbinafine is well absorbed (greater than 70%) and the bioavailability of terbinafine tablets as a result of first-pass metabolism is approximately 40%.
metabolismpharmacokinetics
Following oral administration, terbinafine is well absorbed (greater than 70%) and the bioavailability of terbinafine tablets as a result of first-pass metabolism is approximately 40%.
recorded 2026-08-05 · last checked 2026-09-04
Q6
Which 18 trials of Terbinafine posted no result?
Posted no result
18 of 18 completed trials
Registrations
NCT01286688, NCT01286701, NCT00647647, NCT00648713, NCT00602251 and NCT00602342, and 12 more
Completion dates
oldest 2002-03; newest 2022-08-31
Show the evidence
Trial
NCT01286688
2002-03
NCT01286701
2002-03
NCT00647647
2004-03
NCT00648713
2004-03
NCT00602251
2004-04
NCT00602342
2004-04
12 further recorded trials
NCT00691184
2005-12
NCT00117754
2006-04
NCT01013909
2010-05
NCT01772212
2011-03-15
NCT01484145
2012-04
NCT01080079
2012-06
NCT01790165
2012-06
NCT02145832
2015-11
NCT03135912
2017-08-02
NCT02606032
2021-01-27
NCT04880980
2022-03-15
NCT05578950
2022-08-31
Q7
At the median, Terbinafine's trials enrolled 60 people — anything larger?
Median enrolment
60
Largest enrolment
1029
Registered trials counted
45
Q8
What do 1980 spontaneous reports say about Terbinafine — and not say?
These are reports people sent to a regulator. They do not show the medicine caused the reaction. Nobody counted how many people took the medicine and reported nothing. The same event can be reported more than once, and many reports are incomplete. News coverage, lawsuits and new warnings change how often people report. A count is not a rate and not a risk.
Terbinafine appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 1980 reaction mentions were counted: rash 288; pruritus 247; alanine aminotransferase increased 211; aspartate aminotransferase increased 211. FAERS via Open Targets · CHEMBL1200832 · 2026-06-24
Show the evidence
rash
288
pruritus
247
alanine aminotransferase increased
211
aspartate aminotransferase increased
211
pyrexia
202
ageusia
195
4 more recorded rows
malaise
193
erythema
149
gamma-glutamyltransferase increased
143
dysgeusia
141
recorded 2026-06-24 · last checked 2026-09-04
Q9
Which 10 reactions does Terbinafine's label not list?
In studies in healthy subjects characterized as extensive metabolizers of dextromethorphan (antitussive drug and CYP2D6 probe substrate), terbinafine increases the dextromethorphan/dextrorphan metabolite ratio in urine by 16- to 97-fold on average.
drug_interactions
Thus, terbinafine may convert extensive CYP2D6 metabolizers to poor metabolizer status.
drug_interactions
Fluconazole is an inhibitor of CYP2C9 and CYP3A enzymes.
drug_interactions
Based on this finding, it is likely that other inhibitors of both CYP2C9 and CYP3A4 (e.g., ketoconazole, amiodarone) may also lead to a substantial increase in the systemic exposure (C max and AUC) of terbinafine when concomitantly administered.
pharmacokinetics
Prior to excretion, terbinafine is extensively metabolized by at least 7 CYP isoenzymes with major contributions from CYP2C9, CYP1A2, CYP3A4, CYP2C8, and CYP2C19.
clinical_pharmacology
Prior to excretion, terbinafine is extensively metabolized by at least 7 CYP isoenzymes with major contributions from CYP2C9, CYP1A2, CYP3A4, CYP2C8, and CYP2C19.
ChEMBL 37 — CC BY-SA 3.0 Unported · ClinicalTrials.gov — US Government work · Open Targets 26.06 — CC0 · mixed register set; per-register licences in docs/specs/corpus-20k-sources.md · openFDA / DailyMed — US Government work
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✓ public claims reviewed: 0 reviewed claim(s); drafts are never rendered
✓ source coverage passed: 6 source rows
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