Skip to main content

Oseltamivir Side Effects

Medically reviewed by Last updated on Oct 4, 2021.


Commonly reported side effects of oseltamivir include: nausea and vomiting. Other side effects include: abdominal pain. Continue reading for a comprehensive list of adverse effects.

Applies to oseltamivir: oral capsules, oral extemporaneous oral suspension, oral powder for suspension.

Side effects include:

GI effects (nausea, vomiting, diarrhea, abdominal pain), headache, bronchitis, insomnia, vertigo.

For Healthcare Professionals

Applies to oseltamivir: oral capsule, oral powder for reconstitution.


The most common side effects were nausea and vomiting.

The most common side effects reported with this drug during studies for the treatment of influenza were nausea, vomiting, and headache; the most common side effects reported in prophylaxis studies were nausea, vomiting, headache, and pain. Most side effects were reported on a single occasion, occurred on the first or second day of therapy, and resolved spontaneously within 1 to 2 days.[Ref]

Nervous system

Very common (10% or more): Headache (up to 17%)

Common (1% to 10%): Dizziness, vertigo

Frequency not reported: Drowsiness

Postmarketing reports: Seizure/convulsion[Ref]

Side effects with similar or higher incidence among placebo patients included dizziness and vertigo.[Ref]


Very common (10% or more): Nausea

Common (1% to 10%): Vomiting, diarrhea, abdominal pain, upper abdominal pain, dyspepsia

Frequency not reported: Pseudomembranous colitis

Postmarketing reports: Gastrointestinal bleeding, hemorrhagic colitis[Ref]

Side effects with similar or higher incidence among placebo patients included diarrhea, abdominal pain, upper abdominal pain, and dyspepsia.[Ref]


Common (1% to 10%): Nasal congestion, cough, sore throat, bronchitis, nasopharyngitis, upper respiratory tract infections, influenza, rhinorrhea, sinusitis

Frequency not reported: Pneumonia, peritonsillar abscess, congestion, rhinitis, dry sore throat, epistaxis, asthma, aggravated asthma[Ref]

Side effects with similar or higher incidence among placebo patients included cough, nasal congestion, sore throat, rhinorrhea, bronchitis, sinusitis, nasopharyngitis, upper respiratory tract infections, and influenza.[Ref]


Common (1% to 10%): Insomnia

Frequency not reported: Mania

Postmarketing reports: Abnormal behavior, delirium, altered level of consciousness, confusion, delusions, hallucinations, agitation, anxiety, nightmares, self-injury[Ref]

Influenza can be associated with various neurologic and behavioral symptoms (including hallucinations, delirium, abnormal behavior), with fatal outcomes in some cases; such events may occur with encephalitis or encephalopathy but can occur without obvious severe disease. There are postmarketing reports (mostly in Japan) of delirium and abnormal behavior leading to injury, with fatal outcomes in some cases, in influenza patients using this drug. Although frequency is unknown, based on usage, these events appear uncommon. These events were primarily reported in pediatric patients, often with abrupt onset and rapid resolution. The contribution of this drug to such events has not been established.

Side effects with similar or higher incidence among placebo patients included insomnia.[Ref]


Common (1% to 10%): Fatigue, pain, pyrexia, influenza-like illness, pain in limb, otitis media, earache

Uncommon (0.1% to 1%): Tympanic membrane disorder

Frequency not reported: Humerus fracture, malaise, sepsis, facial edema, ear disorder, accidental injury

Postmarketing reports: Hypothermia[Ref]

Side effects with similar or higher incidence among placebo patients included fatigue, pyrexia, influenza-like illness, and pain in limb.[Ref]


Common (1% to 10%): Herpes simplex

Uncommon (0.1% to 1%): Dermatitis (including allergic and atopic dermatitis)

Rare (less than 0.1%): Angioneurotic edema

Postmarketing reports: Rash, urticaria, eczema, serious skin reactions, toxic epidermal necrolysis, Stevens-Johnson syndrome, erythema multiforme[Ref]

Side effects with similar or higher incidence among placebo patients included herpes simplex.[Ref]


Common (1% to 10%): Back pain, arthralgia, myalgia[Ref]

Side effects with similar or higher incidence among placebo patients included back pain, arthralgia, and myalgia.[Ref]


Common (1% to 10%): Dysmenorrhea

Side effects with similar or higher incidence among placebo patients included dysmenorrhea.


Common (1% to 10%): Conjunctivitis (including red eyes, eye discharge, eye pain)

Postmarketing reports: Visual disturbances[Ref]


Uncommon (0.1% to 1%): Elevated liver enzymes

Rare (less than 0.1%): Hepatic failure, fulminant hepatitis (including fatalities)

Frequency not reported: Hepatic function disorder, jaundice

Postmarketing reports: Hepatitis, abnormal liver function tests[Ref]


Postmarketing reports: Hypersensitivity reactions (e.g., allergic skin reactions), allergy, anaphylactic/anaphylactoid reactions, swelling of the face or tongue[Ref]


Uncommon (0.1% to 1%): Cardiac arrhythmia

Frequency not reported: Unstable angina, sudden cardiopulmonary arrest

Postmarketing reports: Arrhythmia[Ref]


Frequency not reported: Hyperglycemia

Postmarketing reports: Aggravation of diabetes[Ref]


Frequency not reported: Anemia, pancytopenia, lymphadenopathy

Postmarketing reports: Thrombocytopenia[Ref]

Frequently asked questions


1. "Product Information. Tamiflu (oseltamivir)." Roche Laboratories (2001):

2. Hayden FG, Atmar RL, Schilling M, et al. "Use of selective oral neura minidase inhibitor oseltamivir to prevent influenza." N Engl J Med 341 (1999): 1336-43

3. Cox NJ, Hughes JM "New options for the prevention of influenza." N Engl J Med 341 (1999): 1387-8

4. Treanor JJ, Hayden FG, Vrooman PS, et al. "Efficacy and safety of the oral neuramidase inhibitor oseltamivir in treating acute influenza: a randomized controlled trial." JAMA 283 (2000): 1016-24

5. He G, Massarella J, Ward P "Clinical pharmacokinetics of the prodrug oseltamivir and its active metabolite Ro 64-0802." Clin Pharmacokinet 37 (1999): 471-84

6. Bardsley-Elliot A, Noble S "Oseltamivir." Drugs 58 (1999): 851-60

7. Montalto NJ, Gum KD, Ashley JV "Updated treatment for influenza A and B." Am Fam Physician 62 (2000): 2467-76

8. Nicholson KG, Aoki FY, Osterhaus AD, et al. "Efficacy and safety of oseltamivir in treatment of acute influenza: a randomised controlled trial." Lancet 355 (2000): 1845-50

9. Dreitlein WB, Maratos J, Brocavich J "Zanamivir and oseltamivir: Two new options for the treatment and prevention of influenza." Clin Ther 23 (2001): 327-55

10. Welliver R, Monto AS, Carewicz O, et al. "Effectiveness of oseltamivir in preventing influenza in household contacts." JAMA 285 (2001): 748-54

11. McClellan K, Perry CM "Oseltamivir: a review of its use in influenza." Drugs 61 (2001): 263-83

12. Snell P, Dave N, Wilson K, et al. "Lack of effect of moderate hepatic impairment on the pharmacokinetics of oral oseltamivir and its metabolite oseltamivir carboxylate." Br J Clin Pharmacol 59 (2005): 598-601

13. Moscona A "Neuraminidase inhibitors for influenza." N Engl J Med 353 (2005): 1363-73

14. "Antiviral drugs prophylaxis and treatment of influenza." Med Lett Drugs Ther 48 (2006): 87-8

15. McNicholl IR, McNicholl JJ "Neuraminidase inhibitors: zanamivir and oseltamivir." Ann Pharmacother 35 (2001): 57-70

16. Cerner Multum, Inc. "Australian Product Information." O 0

17. Jefferson T, Demicheli V, Rivetti D, Jones M, Di Pietrantonj C, Rivetti A "Antivirals for influenza in healthy adults: systematic review." Lancet 367 (2006): 303-13

18. "New concerns about oseltamivir." Lancet 369 (2007): 1056

19. Strong M, Burrows J, Redgrave P "A/H1N1 pandemic. Oseltamivir's adverse events." BMJ 339 (2009): b3249

20. Jefferson T, Jones M, Doshi P, Del Mar C "Possible harms of oseltamivir-a call for urgent action." Lancet 374 (2009): 1312-3

21. "Antiviral drugs for influenza." Med Lett Drugs Ther 54 (2012): 1-3

22. Anekthananon T, Pukritayakamee S, Ratanasuwan W, et al. "Oseltamivir and inhaled zanamivir as influenza prophylaxis in Thai health workers: a randomized, double-blind, placebo-controlled safety trial over 16 weeks." J Antimicrob Chemother 68 (2013): 697-707

23. "Antiviral drugs for influenza 2012-2013." Med Lett Drugs Ther 54 (2012): 97-8

24. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

25. Hama R "Oseltamivir's adverse reactions: Fifty sudden deaths may be related to central suppression." BMJ 335 (2007): 59

26. Ho LN, Chung JP, Choy KL "Oseltamivir-induced mania in a patient with H1N1." Am J Psychiatry 167 (2010): 350

27. Abe M, Smith J, Urae A, Barrett J, Kinoshita H, Rayner CR "Pharmacokinetics of Oseltamivir in Young and Very Elderly Subjects (October)." Ann Pharmacother (2006):

28. Hankey GJ "Clopidogrel and thrombotic thrombocytopenic purpura." Lancet 356 (2000): 269-70

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.