Tamiflu Side Effects Center

Last updated on RxList: 3/11/2022
Tamiflu Side Effects Center

What Is Tamiflu?

Tamiflu (oseltamivir phosphate) is an antiviral medication used to treat flu symptoms caused by influenza virus in patients who have had symptoms for less than 2 days. Tamiflu may also be given to prevent influenza in people who may be exposed but do not yet have symptoms. Tamiflu will not treat the common cold.

What Are Side Effects of Tamiflu?

Common side effects of Tamiflu include:

  • nausea,
  • vomiting,
  • diarrhea,
  • dizziness,
  • headache,
  • nosebleed,
  • eye redness or discomfort,
  • sleep problems (insomnia), or
  • cough or other respiratory problems.
  • The flu itself or Tamiflu may rarely cause serious mental/mood changes. This may be more likely in children. Tell your doctor of any signs of unusual behavior, including confusion, agitation, or self-injury.

Dosage for Tamiflu

The recommended oral dose of Tamiflu for treatment of influenza in adults and adolescents 13 years and older is 75 mg twice daily for 5 days. Pediatric dose is determined by the child's weight. Tamiflu is not indicated for treatment in pediatric patients less than 1 year of age. Treatment should begin within 2 days of onset of symptoms of influenza.

What Drugs, Substances, or Supplements Interact with Tamiflu?

There may be other drugs that can interact with Tamiflu. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.

Tamiflu During Pregnancy and Breastfeeding

During pregnancy, Tamiflu should be used only when prescribed. This medication passes into breast milk. Consult your doctor before breastfeeding.

Additional Information

Our Tamiflu (oscltamivir phosphate) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Some people using oseltamivir (especially children) have had sudden unusual changes in mood or behavior. It is not certain that oseltamivir is the exact cause of these symptoms. Even without using oseltamivir, anyone with influenza can have neurologic or behavioral symptoms. Call your doctor right away if the person using this medicine has:

  • sudden confusion;
  • tremors or shaking;
  • unusual behavior; or
  • hallucinations (hearing or seeing things that are not there).

Common side effects may include:

  • nausea, vomiting;
  • headache; or
  • pain.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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The following serious adverse reactions are discussed below and elsewhere in the labeling:

  • Serious skin and hypersensitivity reactions [see WARNINGS AND PRECAUTIONS]
  • Neuropsychiatric events [see WARNINGS AND PRECAUTIONS]

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.

The most common adverse reactions in the pooled treatment and pooled prophylaxis trials in adults and adolescents are displayed in Table 5. The majority of these adverse reactions were reported on a single occasion, occurred on either the first or second treatment day and resolved spontaneously within 1-2 days. This summary includes otherwise healthy adults/adolescents and subjects “at risk” (subjects at higher risk of developing complications associated with influenza, e.g., elderly patients and patients with chronic cardiac or respiratory disease). In general, the safety profile in the subjects “at risk” was qualitatively similar to that in otherwise healthy adults/adolescents.

Table 5 : Adverse Reactions Occurring in ≥1% of Adults and Adolescents (13 years of age and older) in Treatment and Prophylaxis Trials*

System Organ Class Adverse Reaction Treatment Trials Prophylaxis Trials
TAMIFLU 75 mg twice daily
(n = 2646)
(n =1977)
TAMIFLU 75 mg once daily
(n = 1943)
(n =1586)
Gastrointestinal Disorders
Nausea 10% 6% 8% 4%
Vomiting 8% 3% 2% 1%
Nervous System Disorders
Headache 2% 1% 17% 16%
General Disorders
Pain <1% <1% 4% 3%
*Adverse reactions that occurred in ≥1% of TAMIFLU-treated adults and adolescents and ≥1% greater in TAMIFLU-treated subjects compared to placebo-treated subjects in either the treatment or prophylaxis trials.

Adverse Reactions From Treatment And Prophylaxis Trials In Pediatric Subjects (1 year to 12 years of age)

A total of 1,481 pediatric subjects (including otherwise healthy pediatric subjects aged 1 year to 12 years and asthmatic pediatric subjects aged 6 to 12 years) participated in clinical trials of TAMIFLU for the treatment of influenza. A total of 859 pediatric subjects received treatment with TAMIFLU for oral suspension either at a 2 mg per kg twice daily for 5 days or weight-band dosing. Vomiting was the only adverse reaction reported at a frequency of ≥1% in subjects receiving TAMIFLU (16%) compared to placebo (8%).

Amongst the 148 pediatric subjects aged 1 year to 12 years who received TAMIFLU at doses of 30 to 60 mg once daily for 10 days in a post-exposure prophylaxis study in household contacts (n = 99), and in a separate 6- week seasonal influenza prophylaxis safety study (n = 49), vomiting was the most frequent adverse reaction (8% on TAMIFLU versus 2% in the no prophylaxis group).

Adverse Reactions From Treatment Trials In Pediatric Subjects (2 weeks to less than 1 year of age)

Assessment of adverse reactions in pediatric subjects 2 weeks to less than 1 year of age was based on two openlabel studies that included safety data on 135 influenza-infected subjects 2 weeks to less than 1 year of age (including premature infants at least 36 weeks post conceptional age) exposed to TAMIFLU at doses ranging from 2 to 3.5 mg per kg of the formulation for oral suspension twice daily orally for 5 days. The safety profile of TAMIFLU was similar across the age range studied, with vomiting (9%), diarrhea (7%) and diaper rash (7%) being the most frequently reported adverse reactions, and was generally comparable to that observed in older pediatric and adult subjects.

Adverse Reactions From The Prophylaxis Trial In Immunocompromised Subjects

In a 12-week seasonal prophylaxis study in 475 immunocompromised subjects, including 18 pediatric subjects 1 year to 12 years of age, the safety profile in the 238 subjects receiving TAMIFLU 75 mg once daily was consistent with that previously observed in other TAMIFLU prophylaxis clinical trials [see Clinical Studies].

Postmarketing Experience

The following adverse reactions have been identified during post-approval use of TAMIFLU. Because these reactions are reported voluntarily from a population of uncertain size, it is not possible to reliably estimate their frequency or establish a causal relationship to TAMIFLU exposure.

General disorders and administration site conditions: Swelling of the face or tongue, allergy, anaphylactic/anaphylactoid reactions, hypothermia

Skin and subcutaneous tissue disorders: Rash, dermatitis, urticaria, eczema, toxic epidermal necrolysis, Stevens-Johnson Syndrome, erythema multiforme [see WARNINGS AND PRECAUTIONS]

Gastrointestinal Disorders: Gastrointestinal bleeding, hemorrhagic colitis

Cardiac Disorders: Arrhythmia

Hepatobiliary Disorders: Hepatitis, abnormal liver function tests

Nervous System Disorders: Seizure

Metabolism and Nutrition Disorders: Aggravation of diabetes

Psychiatric Disorders: Abnormal behavior, delirium, including symptoms such as hallucinations, agitation, anxiety, altered level of consciousness, confusion, nightmares, delusions [see WARNINGS AND PRECAUTIONS]


Influenza Vaccines

Live Attenuated Influenza Vaccine

The concurrent use of TAMIFLU with live attenuated influenza vaccine (LAIV) intranasal has not been evaluated. However, because of the potential for TAMIFLU to inhibit replication of live vaccine virus and possibly reduce the efficacy of LAIV, avoid administration of LAIV within 2 weeks before or 48 hours after TAMIFLU administration, unless medically indicated.

Inactivated Influenza Vaccine

Inactivated influenza vaccine can be administered at any time relative to use of TAMIFLU.

Drugs Without Clinically Significant Drug Interaction With TAMIFLU

No dose adjustments are needed for either oseltamivir or the concomitant drug when coadministering oseltamivir with amoxicillin, acetaminophen, aspirin, cimetidine, antacids (magnesium and aluminum hydroxides and calcium carbonates), rimantadine, amantadine, or warfarin [see CLINICAL PHARMACOLOGY].

Read the entire FDA prescribing information for Tamiflu (Oseltamivir Phosphate)

© Tamiflu Patient Information is supplied by Cerner Multum, Inc. and Tamiflu Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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