This page shows what was measured, who it was measured in, and what that does not settle.
What Oseltamivir does in the body
Used for flu when started within two days of the first symptom.
Influenza gets into a cell by grabbing a sugar on its surface. When the cell has finished building new virus particles, they are still holding on to that same sugar and cannot let go. The virus carries a pair of scissors, an enzyme called neuraminidase, to cut itself free. Oseltamivir is shaped like the sugar those scissors are built to cut, so the scissors close on the drug instead and jam. New particles stay stuck to the cell they came from.
What happened in people
It shortened adult flu symptoms by about 17 hours on average.
✓ Reviewed first-read answer
Where this came from
A person wrote this and a reviewer approved it against this exact record. It carries no effect size.
A reviewer approved this against this record. The reviewed-claim record carrying the exact population and effect size does not exist yet.
No source is stored against this line.
The limit that matters most
Full study reports did not show a clear reduction in hospital admission.
Where it acts
Respiratory epithelial cell surface, at the budding virion
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 C16H28N2O4, weighing 312.4.
US prescribing information · 09e119eb-a8fa-4635-96a7-1b134593cdca · 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.
The limit a reviewer approved as the one that matters most here.
The four opening statements run to 106 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.
Time to first alleviation of symptoms, complications, hospitalisations and adverse events
✓ The study showed what it set out to show
Who was studied
Cochrane CD008965 review of 107 clinical study reports
How many people
9623
Study design
Systematic review of regulatory documents, 20 oseltamivir trials
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
P < 0.0001 for symptom alleviation; no significant effect on hospitalisation (risk difference 0.15%, 95% CI -0.78 to 0.91)
Repeated elsewhere
Partially 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. Half the oseltamivir studies were judged at high risk of selection bias, attrition bias was high, placebo interventions may have contained active substances, and treatment reduced the proportion of participants with a fourfold antibody rise, which was itself used to define the infected population.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral capsule and powder for oral suspension
Interval reported. 95% CI -0
Written into the record, not signed off as a reviewed claim.
Influenza-related lower respiratory tract complications leading to antibiotics, and hospitalisation
✓ The study showed what it set out to show
Who was studied
Kaiser pooled analysis of 10 manufacturer trials
How many people
3564
Study design
Pooled analysis of placebo-controlled trials, eight of them unpublished at the time
Compared against
A dummy treatment
Kind of result
A number that stands in for health
What was found
P < 0.001 for complications, P = 0.02 for hospitalisation
Repeated elsewhere
Failed to Replicate
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. Eight of the ten pooled trials were unpublished when this analysis appeared, and the underlying clinical study reports were not available to independent reviewers for another decade.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral capsule and powder for oral suspension
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Time to alleviation of all symptoms, with complications and admissions as secondary
✓ The study showed what it set out to show
Who was studied
MUGAS individual patient data meta-analysis
How many people
4328
Study design
Individual patient data meta-analysis of nine Roche-sponsored trials
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
P < 0.0001 for symptom alleviation; P = 0.0001 for lower respiratory complications; P = 0.013 for hospitalisation
Repeated elsewhere
Partially 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. Funded by a foundation supported by the manufacturer, and drawing on the same trial programme that the Cochrane review judged at high risk of bias.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral capsule and powder for oral suspension
Interval reported. Not recorded in this summary
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.
Start
Oseltamivir
What a person takes: Oral capsule and powder for oral suspension.
The measurement behind this step
Twice daily for five days for treatment, once daily for prophylaxis, started within 48 hours of symptom onset. The marketed molecule is an ethyl ester prodrug because the active carboxylate is too polar to be absorbed; hepatic carboxylesterase 1 performs the conversion, and the active metabolite is renally cleared so the dose is adjusted for creatinine clearance.
Getting in
Swallowed as an inactive ester, activated by the liver
The capsule contains a version of the drug that cannot work. Liver enzymes cut it into the active form.
╌╌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
Oseltamivir phosphate is an ethyl ester prodrug, converted by hepatic carboxylesterase 1 to oseltamivir carboxylate. The ester exists because the carboxylate itself is too polar to be absorbed orally; bioavailability of the active moiety after the prodrug is roughly 80%. The active metabolite is cleared renally, so dosing follows creatinine clearance.
Distributed to the respiratory tract where infection is
The active drug reaches the airway lining, where influenza replicates.
╌╌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
Oseltamivir carboxylate distributes into the middle ear, sinus and bronchoalveolar lining fluid at concentrations exceeding those needed to inhibit neuraminidase of susceptible strains. Neuraminidase acts on the outside of the cell, so the drug does not need to enter cells at all.
The drug is built to look like the molecule the viral scissors are made to cut, so the scissors close on it and stick.
╌╌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
Oseltamivir carboxylate is a transition-state analogue of sialic acid. Its 3-pentyl ether occupies a hydrophobic pocket that opens when the neuraminidase 150-loop rearranges, and the amino group replaces the natural glycerol substituent. The H275Y substitution in N1 neuraminidase distorts that pocket and is the classic resistance mechanism.
Finished virus particles stay tethered to the cell that made them, and clump together instead of spreading.
╌╌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
With neuraminidase inhibited, progeny virions remain bound by haemagglutinin to sialic acid residues on the host cell surface and aggregate, so release and spread to neighbouring cells are reduced. The drug does not prevent infection of a cell that has already been entered, which is why the 48-hour window exists.
Illness is shortened; whether complications are prevented is the contested part
Symptoms end sooner. Whether the drug stops flu turning into pneumonia or a hospital admission is the question this whole page is about.
╌╌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
The symptom-duration effect is consistent across the clinical study reports, the manufacturer meta-analysis and the independent pragmatic trial, at roughly 16.8 hours, 21% and 1.02 days respectively. The complication effect is reported as substantial by Kaiser 2003 and by MUGAS 2015 and as absent by the Cochrane analysis of the clinical study reports, and that disagreement has never been resolved by a trial designed and powered for the complication endpoint.
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.
Otherwise healthy adults and children with influenza within 48 hours of symptom onset, and people at higher risk of complications; the WHO Expert Committee restricted its recommendation to severe illness in hospitalised patients in 2017.
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 oseltamivir phosphate for prophylaxis of influenza have not been established for pediatric patients less than 1 year of age.”
US prescribing information · 09e119eb-a8fa-4635-96a7-1b134593cdca · read 2026-08-30
On older people, the label states: “Treatment of Influenza Of the 4,765 adults in clinical trials of oseltamivir phosphate for the treatment of influenza, 948 (20%) were 65 years and older, while 329 (7%) were 75 years and older.”
US prescribing information · 09e119eb-a8fa-4635-96a7-1b134593cdca · read 2026-08-30
On people who are pregnant, the label states: “Available published epidemiological data suggest that oseltamivir phosphate, taken in any trimester, is not associated with an increased risk of birth defects.”
US prescribing information · 09e119eb-a8fa-4635-96a7-1b134593cdca · read 2026-08-30
On people who are breastfeeding, the label states: “Risk Summary Based on limited published data, oseltamivir and oseltamivir carboxylate are present in human milk at low levels considered unlikely to lead to toxicity in the breastfed infant.”
US prescribing information · 09e119eb-a8fa-4635-96a7-1b134593cdca · read 2026-08-30
On people with reduced liver function, the label states: “No dosage adjustment is required in patients with mild to moderate hepatic impairment.”
US prescribing information · 09e119eb-a8fa-4635-96a7-1b134593cdca · read 2026-08-30
On people with reduced kidney function, the label states: “Patients with renal impairment had higher blood levels of oseltamivir carboxylate compared to patients with normal renal function which may increase the risk of oseltamivir phosphate-associated adverse reactions.”
US prescribing information · 09e119eb-a8fa-4635-96a7-1b134593cdca · read 2026-08-30
Where the result stopped carrying
The complication and hospitalisation claims of the 2003 manufacturer-pooled analysis did not survive independent analysis of the clinical study reports in 2014
No effect at all on symptom duration in children with asthma
WHO moved oseltamivir from the core to the complementary Essential Medicines List in 2017 and restricted it to critically ill hospitalised patients
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
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 capsule and powder for oral suspension
✎ 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
Twice daily for five days for treatment, once daily for prophylaxis, started within 48 hours of symptom onset.
✎ 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 marketed molecule is an ethyl ester prodrug because the active carboxylate is too polar to be absorbed; hepatic carboxylesterase 1 performs the conversion, and the active metabolite is renally cleared so the dose is adjusted for creatinine clearance.
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
Nausea and vomiting are the commonest adverse effects, with numbers needed to harm of 28 and 22 in adults and 19 for vomiting in children. Cochrane found increased psychiatric adverse events in prophylaxis with a number needed to harm of 94 and a dose-response relationship in the two pivotal treatment trials. Headache and renal events were increased in prophylaxis. Neuropsychiatric events, particularly in adolescents in Japan, prompted label changes and remain the most debated harm.
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 capsule and powder for oral suspension
✎ 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 marketed molecule is an ethyl ester prodrug because the active carboxylate is too polar to be absorbed; hepatic carboxylesterase 1 performs the conversion, and the active metabolite is renally cleared so the dose is adjusted for creatinine clearance.
No source is stored against this line.
What is recorded as being sold
149 products list this as an active ingredient in the United States drug directory. 149 of them contain it and nothing else.
FDA National Drug Code directory · 72205-060 · read 2026-08-29
They are sold as capsule, for suspension, powder, powder, for suspension and suspension, taken oral.
FDA National Drug Code directory · 72205-060 · read 2026-08-29
The regulator's established pharmacologic class for it is neuraminidase inhibitor [epc] and neuraminidase inhibitors [moa].
FDA National Drug Code directory · 72205-060 · read 2026-08-29
80 published labels name it as an active ingredient. 80 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · 09e119eb-a8fa-4635-96a7-1b134593cdca · read 2026-08-29
Those labels are classed as human prescription drug.
US prescribing information · 09e119eb-a8fa-4635-96a7-1b134593cdca · read 2026-08-29
Oseltamivir Phosphate is powder for oral suspension at For oral suspension: 360 mg oseltamivir base supplied as powder (constituted to a final concentration of 6 mg/mL), recorded as prescription product; fda label in effect 2024-05-15 in the United States.
US prescribing information · 005b2784-e410-a50c-e063-6394a90a881c · read 2026-08-27
Recorded price in US: 0.15113 USD per one millilitre, across 10 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 Oseltamivir 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 oseltamivir reduces hospitalisation: the clinical study report analysis found a risk difference of 0.15% with a confidence interval spanning zero
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 it reduces pneumonia: the 1.00% risk difference was for self-reported, investigator-mediated, undefined pneumonia and was not significant in the five trials that used a detailed diagnostic form
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 reduced viral shedding and a clear molecular mechanism imply reduced complications — Cochrane concluded that the mechanism of action proposed by the producers does not fit the clinical evidence
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 Oseltamivir 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.
Symptoms resolve 16.8 hours sooner in adults
In plain words
Across all the trial data, including the trials that were never published, oseltamivir shortened flu symptoms in adults from about 7 days to about 6.3 days.
What was measured
Time to first alleviation of symptoms, intention-to-treat population
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The Cochrane review based on 107 clinical study reports obtained from the European Medicines Agency, GlaxoSmithKline and Roche included 20 oseltamivir trials with 9,623 participants. Time to first alleviation of symptoms in adults was reduced by 16.8 hours (95% CI 8.4 to 25.1; P<0.0001), from 7 days to 6.3 days. In otherwise healthy children the reduction was 29 hours (95% CI 12 to 47; P=0.001). In children with asthma there was no effect.
Written into the record, not signed off as a reviewed claim
Kaiser 2003 claimed a 55% reduction in complications; the clinical study reports did not support it
In plain words
The pooled manufacturer analysis that justified national stockpiles said oseltamivir cut lower respiratory complications by more than half and hospitalisations by 59%. When independent reviewers finally obtained the underlying trial reports, those effects did not hold up.
What was measured
Risk difference for hospitalisation and for serious complications, from clinical study reports rather than journal publications
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Kaiser and colleagues pooled 3,564 subjects from 10 placebo-controlled oseltamivir trials, eight of which were unpublished, and reported that in influenza-positive adults, lower respiratory tract complications leading to antibiotics fell 55% (4.6% versus 10.3%; P<0.001) and hospitalisation for any cause fell 59% (0.7% versus 1.7%; P=0.02). Ten years later, working from 107 clinical study reports, the Cochrane group found no significant effect on hospitalisations in adults (risk difference 0.15%, 95% CI -0.78 to 0.91) and no significant reduction in complications classified as serious or leading to study withdrawal (risk difference 0.07%, 95% CI -0.78 to 0.44). The reduction in pneumonia was 1.00% (95% CI 0.22 to 1.49, number needed to treat 100) but was self-reported and investigator-mediated, was not significant in the five trials that used a more detailed diagnostic form, and no trial defined pneumonia or confirmed it radiologically.
Written into the record, not signed off as a reviewed claim
The trials themselves were not clean, and the review said so in detail
In plain words
The reviewers found problems with how the trials were run and reported, including placebo capsules that may not have been inert and an effect on antibody tests used to decide who counted as having flu.
What was measured
Not recorded
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
Cochrane judged half the oseltamivir studies at high risk of selection bias, found inadequate measures against performance bias in 11 studies because of non-identical placebo presentation, found high attrition bias across the oseltamivir programme and evidence of selective reporting, and noted that the placebo interventions may have contained active substances. Separately, the proportion of participants with a fourfold rise in antibody titre was significantly lower in the treated group (risk ratio 0.92, 95% CI 0.86 to 0.97), a 5% absolute difference, which matters because antibody rise was one of the criteria used to define influenza infection and therefore to define the influenza-infected analysis population.
Written into the record, not signed off as a reviewed claim
Harms are real and quantified: nausea, vomiting, headache, renal and psychiatric events
In plain words
One in 22 adults treated vomits because of the drug, and there was a dose-response relationship with psychiatric events in the two pivotal treatment trials.
What was measured
Risk differences and numbers needed to harm for specific adverse events
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
In adult treatment, oseltamivir increased nausea (risk difference 3.66%, 95% CI 0.90 to 7.39; number needed to harm 28) and vomiting (4.56%, 95% CI 2.39 to 7.58; number needed to harm 22). In children, vomiting had a number needed to harm of 19. In prophylaxis, psychiatric adverse events were increased across the combined on- and off-treatment periods (risk difference 1.06%, 95% CI 0.07 to 2.76; number needed to harm 94), headaches on treatment (3.15%; number needed to harm 32) and nausea on treatment (4.15%; number needed to harm 25). There was a dose-response relationship for psychiatric events between the standard and high dose in the two pivotal treatment trials WV15670 and WV15671 (P=0.038).
Written into the record, not signed off as a reviewed claim
A manufacturer-funded individual-patient meta-analysis then reported the complication effect again
In plain words
A year after the Cochrane review, a different group with different funding pooled the individual patient data and reported that complications and hospitalisations did fall.
What was measured
Risk ratios for lower respiratory tract complications and for hospitalisation, individual patient data
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The MUGAS individual patient data meta-analysis included nine Roche-sponsored randomised placebo-controlled trials with 4,328 adults. In the intention-to-treat infected population, time to alleviation of all symptoms was 21% shorter (time ratio 0.79, 95% CI 0.74 to 0.85; P<0.0001), lower respiratory tract complications requiring antibiotics more than 48 hours after randomisation fell (risk ratio 0.56, 95% CI 0.42 to 0.75; P=0.0001; 4.9% versus 8.7%) and admissions to hospital for any cause fell (risk ratio 0.37, 95% CI 0.17 to 0.81; P=0.013; 0.6% versus 1.7%). Nausea and vomiting were increased. The analysis was funded by the Multiparty Group for Advice on Science foundation, which was itself funded by Roche, and it used the same underlying trial programme that Cochrane had judged at high risk of bias. Both analyses are on this page because a reader should see that the disagreement is live rather than settled.
Written into the record, not signed off as a reviewed claim
ALIC4E: about one day faster recovery in an independent, publicly funded trial
In plain words
A European trial with no manufacturer funding and no placebo found that adding oseltamivir to usual care shortened recovery by about a day on average, and by two to three days in older, sicker patients.
What was measured
Time to recovery, defined as return to usual activities with minor or absent fever, headache and muscle ache
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Open-label, pragmatic, adaptive randomised trial in 15 European countries over three influenza seasons, 3,266 participants aged 1 year and over presenting with influenza-like illness in primary care; 52% had PCR-confirmed influenza. The hazard ratio for time to recovery was 1.29 (95% Bayesian credible interval 1.20 to 1.39), an absolute mean benefit of 1.02 days (95% BCrI 0.74 to 1.31). Benefit ranged from 0.70 days in children under 12 with milder illness to 3.20 days (95% BCrI 1.00 to 5.50) in patients aged 65 and over with comorbidities and longer preceding illness. Nausea and vomiting were increased. The trial was open-label and funded by the European Commission.
Written into the record, not signed off as a reviewed claim
WHO moved oseltamivir off the core Essential Medicines List in 2017
In plain words
After the reanalysis, the WHO expert committee downgraded oseltamivir and restricted its recommendation to severely ill hospitalised patients.
What was measured
Not recorded
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The 2017 WHO Expert Committee on the Selection and Use of Essential Medicines reviewed the additional evidence and concluded that the effect of oseltamivir on hospital admissions and mortality was lower than previously estimated. Oseltamivir was moved from the core to the complementary list and its recommended use limited to severe illness due to confirmed or suspected influenza in critically ill hospitalised patients. Oseltamivir had been added to the list in 2009, during the H1N1 pandemic, on the earlier reading of the evidence.
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.
A neuraminidase inhibitor that shortens influenza symptoms in adults by 16.8 hours, whose claim to prevent pneumonia and hospitalisation rested on a manufacturer-pooled analysis and did not survive the release of the full clinical study reports in 2014.
Recorded evidence blocks (10)
Q1
On the Oseltamivir label: indicated for what?
"Oseltamivir phosphate for oral suspension is an influenza neuraminidase inhibitor (NAI) indicated for: Treatment of acute, uncomplicated influenza A and B in patients 2 weeks of age and older who have been symptomatic for no more than 48 hours. ( 1.1 ) Prophylaxis of influenza A and B in patients 1 year and older.": indications and usage on Oseltamivir's label. DailyMed label · ef093e4d-5b1a-463f-a1a3-b795a4387a81 · 2026-08-24
Q2
124 registered trials of Oseltamivir — at which phases?
Registered studies posting no result
83 of 124
124 registered studies of Oseltamivir: 31 phase1, 31 phase2, 30 phase3, 28 phase4, 7 na, 3 na or unstated, 1 early phase1. CLINICALTRIALS_SNAPSHOT · 2026-09-01
1 to 3 hours; Plasma concentrations of oseltamivir declined with a half-life of 1 to 3 hours in most subjects after oral administration.
metabolismpharmacokinetics
Oseltamivir carboxylate is not further metabolized and is eliminated unchanged in urine.
recorded 2026-08-24 · last checked 2026-09-04
Q6
Which running trial of Oseltamivir could settle lifespan?
NCT04381936 measures Community-acquired pneumonia: All-cause mortality (with subsidiary analyses of cause of death and of death at various timepoints following discharge), reading out 2038-09-30.
1 open trial; n 70000; "Randomised Evaluation of COVID-19 Therapy"
Show the evidence
TrialNCT04381936
"Randomised Evaluation of COVID-19 Therapy"; n 70000; "Community-acquired pneumonia: All-cause mortality (with subsidiary analyses of cause of death and of death at various timepoints following discharge)"; 2038-09-30
Q7
Which 39 trials of Oseltamivir posted no result?
Posted no result
39 of 39 completed trials
Registrations
NCT00416962, NCT00304434, NCT00439530, NCT00334529, NCT00593502 and NCT00921726, and 33 more
Completion dates
oldest 2006-12; newest 2024-04-26
Show the evidence
Trial
NCT00416962
2006-12
NCT00304434
2007-02
NCT00439530
2007-04
NCT00334529
2007-04-10
NCT00593502
2009-06
NCT00921726
2009-10
14 further recorded trials
NCT00935194
2009-11
NCT00980109
2010-09
NCT01049763
2010-10
NCT01388439
2011-01
NCT01258530
2011-02-03
NCT00707941
2011-03
NCT00979251
2011-08
NCT01708369
2012-05
NCT01052961
2012-06
NCT01130636
2012-07
NCT01146535
2012-12
NCT01443806
2012-12
NCT02507648
2013-05
NCT01902342
2013-12
Q8
At the median, Oseltamivir's trials enrolled 97.5 people — anything larger?
Median enrolment
97.5
Largest enrolment
70000
Registered trials counted
124
Q9
What do 2725 spontaneous reports say about Oseltamivir — 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.
Oseltamivir appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 2725 reaction mentions were counted: abnormal behaviour 690; vomiting 442; normal newborn 331; hallucination 307. FAERS via Open Targets · CHEMBL1200340 · 2026-06-24
Show the evidence
abnormal behaviour
690
vomiting
442
normal newborn
331
hallucination
307
pregnancy
274
delirium
199
4 more recorded rows
influenza
196
convulsion
158
premature delivery
72
fatigue
56
recorded 2026-06-24 · last checked 2026-09-04
Q10
Which 10 reactions does Oseltamivir's label not list?
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
✗ 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: 6 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.