This page shows what was measured, who it was measured in, and what that does not settle.
What Ranitidine does in the body
Ranitidine blocks that receptor, so less acid is made and ulcers heal.
Stomach cells make acid when histamine docks on a receptor on their surface. The problem is the molecule's own shape: it carries a nitro group at one end and a dimethylamine at the other, and in the solid tablet those two parts can react with each other over time to produce NDMA, a compound classed as a probable human carcinogen. The drug that reaches the receptor was never the issue. The drug sitting in the bottle was.
Why people take it. A heartburn and ulcer tablet, sold on prescription and over the counter
What happened in people
Ranitidine hydrochloride degrades to NDMA on storage, at a rate driven by solid-state reactive species introduced during crystallisation, milling and grinding
✎ 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 NDMA figures from different analytical methods are comparable — heated-inlet gas chromatography can create NDMA from ranitidine during the analysis
Where it acts
Gastric parietal cell basolateral membrane in the stomach lining
Kind of result
The kind of result is not recorded
Supervision
Professional supervision is normally required. It is a prescription or clinician-administered medicine where it is approved.
What the registries record it as
The substance registry classes this as chemical.
FDA substance registry · 884KT10YB7 · read 2026-08-29
Its recorded molecular formula is C13H22N4O3S•HCl, weighing 350.87.
US prescribing information · d0da9dd6-c691-4614-99c7-531b0bf34837 · read 2026-08-30
Where each sentence above came from
A person wrote this explanation into the record, with the studies named in the path below.
The recorded use, written for a reader without medical training. Not signed off.
A limit recorded against this substance. Not signed off as a reviewed claim.
The four opening statements run to 122 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.
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.
Incident cancer risk in new ranitidine users versus new users of other histamine H2 receptor antagonists, with lag times up to six years
✗ The study did not show it
Who was studied
National Health Insurance Service-National Sample Cohort, South Korea (Joung et al.)
Overall cancer incidence 2.9 versus 3.0 per 1000 person-years; adjusted hazard ratio 0.98 (95% CI 0.81 to 1.20); no dose-response with higher cumulative exposure
Repeated elsewhere
Partially Replicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. The authors state that the follow-up period is insufficient for an endpoint with the latency of chemical carcinogenesis, so the null result constrains rather than excludes an effect.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, effervescent tablet, syrup and injection
Interval reported. 95% CI 0
Written into the record, not signed off as a reviewed claim.
RNAWiki holds 1 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.
Start
Ranitidine
What a person takes: Oral tablet, effervescent tablet, syrup and injection.
The measurement behind this step
Ranitidine hydrochloride given orally at 150 mg twice daily or 300 mg nightly for ulcer healing, with lower strengths sold over the counter, plus a syrup and an intravenous formulation. Roughly 50 per cent bioavailable with a two to three hour half-life and substantial renal clearance.
Getting in
An oral tablet, prescription or over the counter
Taken by mouth once or twice a day, or as needed for heartburn.
╌╌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
Oral ranitidine hydrochloride, 150 mg twice daily or 300 mg at night for ulcer healing, with lower over-the-counter strengths for heartburn. Roughly 50 per cent oral bioavailability with a two to three hour half-life.
Absorbed from the gut and carried in the blood to the acid-producing cells in the stomach wall.
╌╌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
Distributes to the gastric mucosa and reaches the basolateral membrane of parietal cells, where the histamine H2 receptor sits. Largely renally cleared, so dose reduction is needed in renal impairment.
It occupies the docking site histamine would use, so the acid-producing signal never gets through.
╌╌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
Competitive, reversible antagonism at the H2 receptor, a Gs-coupled receptor. Occupancy prevents histamine-driven adenylate cyclase activation and the rise in intracellular cyclic AMP.
Without that signal, the molecular pumps that push acid into the stomach are not switched on.
╌╌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
Reduced cyclic AMP means reduced protein kinase A signalling and less trafficking and activation of the H+/K+ ATPase at the secretory canaliculus. Gastrin and acetylcholine inputs remain, which is why H2 blockade suppresses acid less completely than a proton pump inhibitor.
Acid falls and ulcers heal — and NDMA accumulates in the bottle
The drug did its job for forty years. The reason it is gone is a reaction happening inside the tablet, not inside the patient.
╌╌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
Measured: reliable gastric acid suppression and ulcer healing since 1983, with no efficacy claim contested at withdrawal. Measured: NDMA formation on storage driven by solid-state reactive species, with cryoground material degrading up to two orders of magnitude faster than unprocessed drug substance.
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 5 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.
Nobody in the United States. Patients moved to famotidine, which has no dimethylamine group, or to the proton pump inhibitors.
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: “Safety and effectiveness in neonates (less than 1 month of age) have not been established (see CLINICAL PHARMACOLOGY: Pediatrics ).”
US prescribing information · d0da9dd6-c691-4614-99c7-531b0bf34837 · read 2026-08-30
On older people, the label states: “Geriatrics The plasma half-life is prolonged and total clearance is reduced in the elderly population due to a decrease in renal function.”
US prescribing information · d0da9dd6-c691-4614-99c7-531b0bf34837 · read 2026-08-30
On people who are pregnant, the label states: “Teratogenic Effects Pregnancy Category B Reproduction studies have been performed in rats and rabbits at doses up to 160 times the human dose and have revealed no evidence of impaired fertility or harm to the fetus due to ranitidine.”
US prescribing information · d0da9dd6-c691-4614-99c7-531b0bf34837 · read 2026-08-30
On people who are breastfeeding, the label states: “Caution should be exercised when this product is administered to a nursing mother.”
US prescribing information · d0da9dd6-c691-4614-99c7-531b0bf34837 · read 2026-08-30
Where the result stopped carrying
Approved 1983, and all ranitidine products were requested off the United States market from 1 April 2020
The failure is a manufacturing and stability failure: the same molecule can be made to degrade quickly or barely at all depending on processing
Drugs@FDA records for ranitidine hydrochloride applications carry Discontinued marketing status
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.
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 (11)
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.
There was nothing to correct
Where a level is already normal, topping it up may change nothing. 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
Withdrawn
❝ 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 tablet, effervescent tablet, syrup and injection
✎ 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
Professional supervision is normally required. It is a prescription or clinician-administered medicine where it is approved.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
A register records the withdrawal of an approval.
No source is stored against this line.
What is in the pack
Ranitidine hydrochloride given orally at 150 mg twice daily or 300 mg nightly for ulcer healing, with lower strengths sold over the counter, plus a syrup and an intravenous formulation. Roughly 50 per cent bioavailable with a two to three hour half-life and substantial renal clearance.
✎ 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 and what that means for what is in the pack.
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
The pharmacological safety profile was unremarkable across nearly four decades: headache, dizziness, constipation or diarrhoea, rare hepatitis, and rare thrombocytopenia, with dose reduction required in renal impairment. The withdrawal is not about any of that. All ranitidine products were requested off the United States market from 1 April 2020 because the molecule degrades to N-nitrosodimethylamine, classified as a probable human carcinogen, at rates that increase with temperature, time, and the defect content of the crystalline drug substance. Cohort data against other H2 antagonists have not so far shown an increase in cancer incidence, on follow-up the authors describe as insufficient.
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 tablet, effervescent tablet, syrup and injection
✎ 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
Roughly 50 per cent bioavailable with a two to three hour half-life and substantial renal clearance.
✎ 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 which forms are sold and how they compare.
No source is stored against this line.
What is recorded as being sold
24 products list this as an active ingredient in the United States drug directory. 24 of them contain it and nothing else.
FDA National Drug Code directory · 38779-3186 · read 2026-08-29
They are sold as capsule, powder, syrup, tablet, tablet, coated and tablet, film coated, taken oral.
FDA National Drug Code directory · 38779-3186 · read 2026-08-29
The regulator's established pharmacologic class for it is histamine h2 receptor antagonists [moa] and histamine-2 receptor antagonist [epc].
FDA National Drug Code directory · 38779-3186 · read 2026-08-29
9 published labels name it as an active ingredient. 9 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · aab81d9f-397d-49fb-8083-77a1872cc71f · read 2026-08-29
Those labels are classed as human otc drug and human prescription drug.
US prescribing information · aab81d9f-397d-49fb-8083-77a1872cc71f · read 2026-08-29
Ranitidine is oral at HOW SUPPLIED Ranitidine Syrup (Ranitidine Oral Solution USP), a clear, pale yellow, spearmint-flavored liquid, contains 16.8 mg of ranitidine hydrochloride equivalent to 15 mg of ranitidine per 1 mL of oral solution (75…, recorded as fda label in effect 2022-01-12 in the United States.
US prescribing information · d0da9dd6-c691-4614-99c7-531b0bf34837 · read 2026-08-30
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.
Self-experiment planning is not offered for a prescription or clinician-supervised medicine, withdrawn medicine. The questions below are for a clinician or pharmacist.
Questions worth asking
Which of the trials of Ranitidine 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 NDMA figures from different analytical methods are comparable — heated-inlet gas chromatography can create NDMA from ranitidine during the analysis
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 null cohort result establishes safety; the authors identify the follow-up as insufficient for a long-latency carcinogenic endpoint
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 withdrawal implies anything about the H2 antagonist class, which continues unchanged in famotidine
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 Ranitidine 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.
NDMA forms inside the product, and manufacturing defects drive the rate
In plain words
Ranitidine turns into NDMA over time in the bottle. How fast depends on damage introduced to the crystals during manufacturing — grinding a sample made it degrade up to a hundred times faster.
What was measured
NDMA formation rate against solid-state reactive species content in ranitidine hydrochloride under accelerated storage
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Ranitidine hydrochloride degrades to N-nitrosodimethylamine on storage, and earlier work linked the rate to crystal morphology. A controlled study identified solid-state reactive species introduced during crystallisation, milling and grinding as the primary driver. Cryogenic milling was used to introduce these species systematically, and stability testing at 60 degrees and 0 per cent relative humidity showed a clear relationship between the amount of solid-state reactive species present and the amount of NDMA formed, with cryoground samples degrading at rates up to two orders of magnitude higher than unprocessed samples. Tablets manufactured with increased solid-state reactive species also showed accelerated formation. The variable is the processing history of the powder, not the identity of the drug.
Written into the record, not signed off as a reviewed claim
Recrystallisation stops it, which confirms where the problem lives
In plain words
Recrystallising the drug — undoing the crystal damage — stops the NDMA forming. That is the clearest proof that the fault is in how the powder was made, not in the molecule's function.
What was measured
Nitrosamine formation after recrystallisation of ranitidine hydrochloride versus untreated material
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Subsequent work reports that recrystallisation of ranitidine hydrochloride can stop nitrosamine formation, and separate work reports mitigation by spray-drying co-precipitation. Both are interventions on the solid form rather than on the molecular structure. This is the decisive category evidence for the whole page: an intervention that changes nothing about what ranitidine does at the H2 receptor, and everything about whether it makes NDMA in the container, resolves the problem. It follows that the 2020 withdrawal was a judgement about a supply chain and its manufacturing controls rather than about a pharmacological hazard.
Written into the record, not signed off as a reviewed claim
The measured cancer signal in patients has not matched the chemical signal
In plain words
Cohort studies comparing ranitidine users with users of other heartburn drugs of the same class have not found a higher cancer rate.
What was measured
Adjusted hazard ratio for incident cancer, ranitidine versus other H2 receptor antagonists, in 25,360 propensity-matched patients
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
A cohort study using the South Korean National Health Insurance Service National Sample Cohort (2002 to 2015) compared new users of ranitidine with new users of other histamine H2 receptor antagonists as an active comparator, in patients aged 40 or over with no H2 antagonist prescription in the prior two years, with lag times up to six years. After exclusions and propensity score matching, 25,360 patients were analysed. Ranitidine use was not associated with overall cancer risk — incidence 2.9 against 3.0 per 1000 person-years, adjusted hazard ratio 0.98 (95% CI 0.81 to 1.20) — nor with major individual cancers, and higher cumulative exposure did not raise risk. The authors state the limitation directly: the follow-up period is insufficient for a carcinogenic endpoint with a long latency. A null result at this duration constrains the size of any effect; it does not exclude one.
Written into the record, not signed off as a reviewed claim
A measured NDMA number means nothing without its analytical method
In plain words
Some early testing heated the samples, and heating ranitidine makes NDMA during the test itself. The headline numbers and the regulatory numbers were not measured the same way.
What was measured
That NDMA figures reported for ranitidine products are comparable across analytical methods
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Ranitidine can generate NDMA under heat, which is the property that makes an analytical method choice into a scientific dispute. A gas chromatographic method with a heated inlet can convert intact ranitidine to NDMA inside the instrument, so a result obtained that way conflates the NDMA present in the product with NDMA created during the analysis. Liquid chromatography with high-resolution mass spectrometry at ambient temperature avoids this. The consequence for a reader is concrete: any statement of the form "ranitidine contained N nanograms of NDMA" is uninterpretable without knowing which method produced it, and figures from different methods are not comparable to each other or to an acceptable intake limit.
Written into the record, not signed off as a reviewed claim
The withdrawal removed a whole molecule and left the drug class intact
In plain words
Every ranitidine product went. Famotidine, which does exactly the same thing at the same receptor, was untouched.
What was measured
Not recorded
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The 2020 action covered all ranitidine products, prescription and over the counter, brand and generic. Famotidine, a histamine H2 receptor antagonist with the same target and the same clinical indications, was unaffected and absorbed the market. The structural reason is direct: NDMA formation requires a dimethylamine and a nitrosating source, and ranitidine carries both in one molecule while famotidine carries neither. That a therapeutic class survives intact when one member is removed for a chemical property peculiar to that member is the cleanest available demonstration that the harm did not belong to the pharmacology. Every other withdrawal in this file removed a mechanism; this one removed a molecule.
Written into the record, not signed off as a reviewed claim
It works, and that was never disputed
In plain words
Ranitidine was an effective acid-reducing drug for nearly forty years. No part of the withdrawal contests that.
What was measured
Not recorded
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Ranitidine was approved in the United States in 1983 and became one of the most widely prescribed drugs in the world, healing duodenal and gastric ulcers, controlling reflux oesophagitis, and available over the counter for heartburn. The withdrawal documents make no efficacy claim against it. This distinguishes it sharply from most of this file: rofecoxib, troglitazone and pergolide all worked and were removed because of what they did to patients, and ranitidine worked and was removed because of what it did to itself on a shelf. The correct summary is that a satisfactory drug became an unsatisfactory product.
Source
Drugs@FDA ranitidine hydrochloride application records, marketing status Discontinued
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
verified
Review state
Written into the record, not signed off as a reviewed claim
The episode reset nitrosamine control across the whole industry
In plain words
What began with a blood pressure drug and continued with ranitidine changed how every manufacturer tests for this class of impurity.
What was measured
Not recorded
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Nitrosamine impurities were first found in sartan blood pressure drugs in 2018, then in ranitidine and nizatidine in 2019 and 2020, then in metformin. The industry response is now a permanent one: risk assessment for nitrosamine formation across drug substances and products, control strategies at the level of the manufacturing process rather than the final assay, and the body of work on solid-state reactive species, recrystallisation and spray-drying co-precipitation that this page cites. Ranitidine is the case that made a process control a regulatory expectation rather than good practice.
This order is fixed in code and does not count clicks or time on the page.
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 H2 receptor antagonist withdrawn worldwide in 2020 not for anything it does in the body but because the molecule degrades in the container to N-nitrosodimethylamine, a degradation now shown to be driven by solid-state reactive species introduced during crystallisation, milling and grinding — with cryoground material degrading up to two orders of magnitude faster than unprocessed drug.
"Superiority of iv omeprazole to ranitidine has already been proven by others."; 9 of 52 registered studies
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Trial
NCT00247130
withdrawn; "Superiority of iv omeprazole to ranitidine has already been proven by others."
NCT00443963
withdrawn; "The study was not approved by the Human Studies Subcommittee."
NCT00527878
terminated; "Failure to enroll adequate patient numbers due to small number of eligible patients"
NCT00668317
terminated; "Primary care physicians began prescribing antacid therapy for chronic cough"
NCT02123498
withdrawn; "IRB not approved"
NCT02999633
terminated; "Due to an unsatisfactory benefit/risk ratio, as specified in \& 14.8.1 of the protocol, Sanofi decided to stop enrollment and terminate ACT14596 prematurely"
3 further recorded trials
NCT03368664
terminated; "Enrolment formally closed earlier than planned due to recruitment challenges."
NCT03468777
terminated; "The study has been terminated due to pending data analysis"
NCT05035407
terminated; "Site plans to become a site for a multicenter study of this therapy"
recorded 2026-09-01 · last checked 2026-09-04
Q4
Human studies of Ranitidine used Zantac 300 mg tablets of Glaxosmithkline — over how long?
Human studies of Ranitidine used "Zantac 300 mg tablets of Glaxosmithkline". ClinicalTrials.gov · 2026-09-01
3 recorded entries; human; also "ranitidine 150 mg", "lesinurad 400 mg + ranitidine 150 mg"
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human
NCT01131702
Zantac 300 mg tablets of Glaxosmithkline
NCT01908257
ranitidine 150 mg
NCT01908257
lesinurad 400 mg + ranitidine 150 mg
recorded 2026-09-01 · last checked 2026-09-04
Q5
Ranitidine's half-life is 2.5 to 3 hours — which schedules were studied?
2.5 to 3 hours; The elimination half-life is 2.5 to 3 hours.
bioavailabilitypharmacokinetics
48 %; The average bioavailability of ranitidine given orally to pediatric patients is 48% which is comparable to the bioavailability of ranitidine in the adult population.
metabolismpharmacokinetics
Metabolism In humans, the N-oxide is the principal metabolite in the urine; however, this amounts to <4% of the dose.
recorded 2022-01-12 · last checked 2026-09-04
Q6
Which 21 trials of Ranitidine posted no result?
Posted no result
21 of 21 completed trials
Registrations
NCT00000964, NCT01538797, NCT00633412, NCT01131702, NCT00633672 and NCT00702871, and 15 more
Completion dates
oldest 1990-10; newest 2018-10-24
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Trial
NCT00000964
1990-10
NCT01538797
1996-08
NCT00633412
2003-03
NCT01131702
2003-03
NCT00633672
2003-10
NCT00702871
2006-04
14 further recorded trials
NCT00590928
2006-06
NCT00247715
2007-01
NCT00405119
2007-03
NCT01392755
2011-09
NCT02555852
2012-02
NCT01539655
2012-09
NCT01682408
2012-12
NCT02004197
2013-01
NCT01908257
2013-11
NCT02197143
2014-07
NCT02733640
2015-05
NCT02205489
2016-04
NCT02441894
2016-11
NCT00223691
2017-01
Q7
At the median, Ranitidine's trials enrolled 41.5 people — anything larger?
Median enrolment
41.5
Largest enrolment
4238504
Registered trials counted
52
Q8
What do 1745 spontaneous reports say about Ranitidine — 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.
Ranitidine appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 1745 reaction mentions were counted: drug hypersensitivity 300; erythema 214; hypotension 192; anaphylactic reaction 190. FAERS via Open Targets · CHEMBL1790041 · 2026-06-24
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drug hypersensitivity
300
erythema
214
hypotension
192
anaphylactic reaction
190
hypersensitivity
180
gastrooesophageal reflux disease
155
4 more recorded rows
asthma
143
hyperhidrosis
128
prostate cancer
124
angioedema
119
recorded 2026-06-24 · last checked 2026-09-04
Q9
Which 10 reactions does Ranitidine's label not list?
ChEMBL 37 — CC BY-SA 3.0 Unported · ChEMBL ATC CC BY-SA · 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
✗ required summary fields resolved: 4 required field(s) not terminal: Why people use it, Best-supported result, Biggest unanswered question, Human evidence
✓ public claims reviewed: 0 reviewed claim(s); drafts are never rendered
✓ source coverage passed: 7 source rows
✓ no critical contamination: no quarantine open
✓ canonical metadata passed: slug and display name present
✓ no raw internal fields: enforced by the copy-contract test over the rendered page
This is a record of evidence. It is not medical advice, and it does not say this substance suits you. Nothing here says any substance on RNAWiki is appropriate for a child.