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Tamiflu Side Effects

Generic Name: oseltamivir

Note: This document contains side effect information about oseltamivir. Some of the dosage forms listed on this page may not apply to the brand name Tamiflu.

In Summary

Common side effects of Tamiflu include: nausea and vomiting. Other side effects include: abdominal pain. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to oseltamivir: oral capsule, oral powder for suspension

Along with its needed effects, oseltamivir (the active ingredient contained in Tamiflu) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking oseltamivir:

Less common Rare
  • Abdominal or stomach cramps or tenderness
  • arm, back, or jaw pain
  • bloating
  • chest pain or discomfort
  • diarrhea, watery and severe, which may also be bloody
  • drooling
  • facial swelling
  • fast or irregular heartbeat
  • hoarseness
  • increased thirst
  • pain
  • shortness of breath
  • unusual weight loss
Incidence not known
  • Blistering, peeling, or loosening of the skin
  • convulsions (seizures)
  • dark urine
  • difficulty with swallowing
  • fainting
  • fast, slow, or irregular heartbeat
  • hives or welts
  • itching, puffiness, or swelling of the eyelids or around the eyes, face, lips, or tongue
  • joint or muscle pain
  • light-colored stools
  • loss of bladder control
  • loss of consciousness
  • muscle spasm or jerking of all extremities
  • red skin lesions, often with a purple center
  • red, irritated eyes
  • skin rash or itching over the entire body
  • sores, ulcers, or white spots in the mouth or on the lips
  • sweating
  • upper right abdominal or stomach pain
  • yellow eyes and skin

Some side effects of oseltamivir may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common Less common
  • Abdominal or stomach pain
  • bloody nose or unexplained nosebleeds (occurs mainly in children)
  • burning, dry, or itching eyes (mainly in children)
  • dizziness
  • ear disorder (occurs mainly in children)
  • excessive tearing of the eyes (mainly in children)
  • redness, pain, or swelling of the eye or eyelid (mainly in children)
  • trouble with sleeping
  • Pale skin
  • troubled breathing
  • unusual bleeding or bruising
Incidence not known
  • blurred vision
  • cracked, dry, or scaly skin
  • dry mouth
  • flushed, dry skin
  • mood or mental changes
  • skin rash that is encrusted, scaly, and oozing

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, headache, bronchitis, insomnia, and vertigo. Nausea and vomiting were generally mild to moderate in severity and usually occurred on the first 2 days of therapy. Less than 1% of patients discontinued this drug early due to nausea and vomiting.

Side effects in prophylaxis studies were similar to those in treatment studies, most commonly nausea, vomiting, headache, and pain. Side effects that occurred more frequently than in treatment studies were aches and pains, rhinorrhea, dyspepsia, and upper respiratory tract infections.[Ref]

Nervous system

Very common (10% or more): Headache (up to 18%)
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%): Nausea (without vomiting), 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]


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%): 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 herpes simplex.[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]


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]


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

Common (1% to 10%): Dysmenorrhea


Common (1% to 10%): Conjunctivitis (including red eyes, eye discharge, eye pain)
Rare (less than 0.1%): 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]


Frequency not reported: Unstable angina, sudden cardiopulmonary arrest
Postmarketing reports: Cardiac arrhythmia[Ref]


Frequency not reported: Hyperglycemia
Postmarketing reports: Aggravation of diabetes[Ref]


Frequency not reported: Anemia, pancytopenia, lymphadenopathy
Postmarketing reports: Thrombocytopenia[Ref]


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Some side effects of Tamiflu may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

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