Oseltamivir Side Effects

Medically reviewed by Drugs.com. Last updated on Sep 24, 2024.

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

Common side effects of oseltamivir

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 side effects

• diarrhea
• nausea
• vomiting

Less common side effects

• 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

Rare side effects

• 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

Serious side effects of oseltamivir

Along with its needed effects, oseltamivir 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 side effects

• phlegm-producing cough
• wheezing

Rare side effects

• 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

For healthcare professionals

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

General adverse events

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]

Gastrointestinal

• 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]

Respiratory

• 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]

Psychiatric

• 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]

Other

• 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]

Dermatologic

• 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]

Musculoskeletal

• 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]

Genitourinary

• Common (1% to 10%): Dysmenorrhea

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

Ocular

• Common (1% to 10%): Conjunctivitis (including red eyes, eye discharge, eye pain)
• Postmarketing reports: Visual disturbances^[Ref]

Hepatic

• 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]

Hypersensitivity

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

Cardiovascular

• Uncommon (0.1% to 1%): Cardiac arrhythmia
• Frequency not reported: Unstable angina, sudden cardiopulmonary arrest
• Postmarketing reports: Arrhythmia^[Ref]

Metabolic

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

Hematologic

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

Frequently asked questions

• Does Tamiflu (oseltamivir) work on COVID-19?
• What is the difference between Xofluza and Tamiflu?

Further information

Oseltamivir side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer