What the label lists and what reports show
Oseltamivir side effects
Oseltamivir's FDA label: “Most common adverse reactions (>1% and more common than with placebo): Treatment studies – Nausea, vomiting, headache.” FAERS holds 24,281 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is vomiting (2,082 reports).
- Generic listed
Check it at the source: the oseltamivir FDA label on DailyMed (effective December 15, 2025, Genentech, Inc.); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of TAMIFLU?TAMIFLU may cause serious side effects, including: Serious skin and allergic reactions. TAMIFLU can cause serious skin and allergic reactions. Stop taking TAMIFLU and get medical help right away if you get any of the following symptoms: skin rash or hives your skin blisters and peels blisters or sores in your mouth itching swelling of your face, eyes, lips, tongue, or throat trouble breathing chest pain or tightness Change in behavior. People, especially children, who have the flu, can develop nervous system problems and abnormal behavior that can lead to death. During treatment with TAMIFLU, tell your healthcare provider right away if you or your child have confusion, speech problems, shaky movements, seizures, or start hearing voices or seeing things that are not really there (hallucinations). […]
Source: FDA drug label, NDA021087 (Roche), as published by Genentech, Inc., effective December 15, 2025 (SPL set ee3c9555-60f2-4f82-a760-11983c86e97b), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions (>1% and more common than with placebo): Treatment studies – Nausea, vomiting, headache.
Table 5 Adverse Reactions Occurring in ≥1% of Adults and Adolescents (13 years of age and older) in Treatment and Prophylaxis Trials Adverse reactions that occurred in ≥1% of TAMIFLU-treated adults and adolescents and…
| Adverse Reaction | TAMIFLU 75 mg twice daily (n = 2646) | Placebo (n = 1977) | TAMIFLU 75 mg once daily (n = 1943) | Placebo (n = 1586) |
|---|---|---|---|---|
| Nausea | 10% | 6% | 8% | 4% |
| Vomiting | 8% | 3% | 2% | 1% |
| Headache | 2% | 1% | 17% | 16% |
| Pain | <1% | <1% | 4% | 3% |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following serious adverse reactions are discussed below and elsewhere in the labeling: Serious skin and hypersensitivity reactions [see Warnings and Precautions (5.1) ] Neuropsychiatric events [see Warnings and Precautions (5.2) ] Most common adverse reactions (>1% and more common than with placebo): Treatment studies – Nausea, vomiting, headache. ( 6.1 ) Prophylaxis studies – Nausea, vomiting, headache, pain. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Genentech at 1-888-835-2555 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Adverse Reactions from Treatment and Prophylaxis Trials in Adult and Adolescent Subjects (13 years of age and older) The overall safety profile of TAMIFLU is based on data from 2,646 adult and adolescent subjects that received the recommended dosage of 75 mg orally twice daily for 5 days for treatment of influenza and 1,943 adult and adolescent subjects that received the recommended dosage of 75 mg orally once daily for up to 6 weeks for prophylaxis of influenza in clinical trials. …
Source: FDA drug label, NDA021087 (Roche), as published by Genentech, Inc., effective December 15, 2025 (SPL set ee3c9555-60f2-4f82-a760-11983c86e97b), via openFDA; the full label on DailyMed
What do FAERS reports show?
24,281 reports list oseltamivir among the medicines taken, each a report of something that happened, not proof the medicine caused it; 2,714 are coded as a death and 6,550 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 18 reactions below, 8 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Oseltamivir: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions