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Oseltamivir oral capsule side effects: A detailed guide

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More common side effectsMild side effectsSerious side effectsFAQSide effects in detailWarnings
Oseltamivir oral capsule is prescribed to treat and prevent flu. It’s an antiviral drug that may cause mild or serious side effects. These include nausea, vomiting, and headache.
Medically reviewed by Molly Becze, PharmD, BCPS
Updated on

This article describes possible side effects of oseltamivir oral capsule. You can learn more about oseltamivir by talking with your doctor.

Oseltamivir oral capsule is a generic version of the brand-name drug Tamiflu. Oseltamivir also comes in a suspension (a type of liquid mixture) that you swallow, but this form isn’t described in this article. To learn more about this form, talk with your doctor.

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More common side effects of oseltamivir

Oseltamivir oral capsule may cause mild or serious side effects. Below are some of the more common side effects that occurred during the drug’s studies. The more common side effects varied based on the use of the medication.

More common side effects reported in people taking oseltamivir oral capsule for treatment of flu include:

More common side effects reported in people taking oseltamivir oral capsule for prevention of flu include:

  • nausea
  • vomiting
  • headache
  • pain

Mild side effects of oseltamivir

Oseltamivir may cause certain mild side effects. Usually, mild side effects are temporary and can be easily managed. Tell your doctor or pharmacist if you have side effects that don’t go away or become bothersome.

Mild side effects of oseltamivir oral capsule that occurred in studies include:

  • nausea
  • vomiting
  • headache
  • pain

Oseltamivir oral capsule may cause more mild side effects than those listed above. For details, see the drug’s prescribing information.

Serious side effects of oseltamivir

Oseltamivir may cause certain serious side effects. If you have any serious side effects from oseltamivir oral capsule, call your doctor right away. But if you think you’re having a medical emergency or your side effects feel life threatening, take immediate action. Call 911 or a local emergency number, or go to the nearest emergency room.

After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. Visit MedWatch’s website if you’d like to notify the FDA about a side effect you’ve had with oseltamivir.

Serious side effects of oseltamivir oral capsule that occurred in studies include:

  • severe skin reactions*†
  • unusual behavior and delirium*†

* To learn more about this side effect, see the “Side effects of oseltamivir in detail” section below.
This side effect wasn’t reported in studies of the drug. But it has occurred in people after the drug was approved for use.

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Allergic reaction

For some people, oseltamivir oral capsule can cause an allergic reaction. But this side effect wasn’t reported in the drug’s studies.

In general, symptoms of an allergic reaction can be mild or serious. You can learn more about possible symptoms in this article.

Ways to manage

For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep taking the medication.

For severe allergic reaction symptoms, such as swelling or difficulty breathing, call 911 or your local emergency number right away. These symptoms require immediate medical care because they can become life threatening. If you’ve had a serious allergic reaction to oseltamivir oral capsule, your doctor may recommend taking a different medication instead.

Common questions about side effects of oseltamivir

Here are answers to some common questions about side effects of oseltamivir oral capsule. If you have other questions, talk with your doctor or pharmacist.

Does Tamiflu, oseltamivir’s brand-name version, cause long-term side effects?

Long-term side effects aren’t expected with generic oseltamivir oral capsule or Tamiflu. In studies, specific side effects weren’t seen in people who had taken the drug for a long time. Long lasting side effects after treatment ended also weren’t reported.

Talk with your doctor if you have more questions about possible long-term side effects with Tamiflu or oseltamivir.

How do the side effects of Tamiflu compare in older adults vs. younger adults?

In studies, oseltamivir oral capsule, the generic version of Tamiflu, caused similar side effects in older adults (ages 65 years and older) and younger adults.

However, older adults may clear oseltamivir from their bodies more slowly than younger adults. This may lead to higher levels of oseltamivir in their body, which can increase their risk of side effects.

If you have concerns about taking oseltamivir oral capsule because of your age, talk with your doctor.

Is death a side effect of Tamiflu, oseltamivir’s brand-name version?

It’s not likely. However, people who are sick with flu are at risk of developing nervous system problems and unusual behavior that can lead to death.

This wasn’t a side effect seen during studies of oseltamivir. There have been reports of death among people taking oseltamivir, but it’s unclear how often this has happened or if oseltamivir was the cause.

If you have concerns about this, talk with your doctor.

Side effects of oseltamivir in detail

Below you’ll find details on some of the side effects of oseltamivir oral capsule.

Severe skin reactions

In rare cases, oseltamivir oral capsule may cause severe skin reactions. But it’s important to note that severe skin reactions weren’t seen during studies of oseltamivir. There have been reports of this side effect in people taking oseltamivir, but it’s unclear how often this has happened or if oseltamivir was the cause.

Examples of severe skin reactions include toxic epidermal necrolysis, Stevens-Johnson syndrome, and erythema multiforme. Symptoms may include:

  • skin rash or hives
  • skin blistering or peeling
  • swelling of the face, eyes, lips, tongue, or throat
  • blisters or sores in your mouth
  • chest pain or tightness
  • itching
  • difficulty breathing

Ways to manage

If you experience symptoms of a serious skin reaction, get medical help right away. In some cases, these skin reactions can become life threatening. Your doctor will likely recommend that you stop taking oseltamivir.

Abnormal behavior

Oseltamivir may cause nervous system problems and changes in behavior, especially in children. In rare cases, this can lead to death. But this side effect wasn’t seen in studies of the drug. There have been reports of death among people who have taken oseltamivir, but it’s not known how frequently this has occurred or if oseltamivir was the cause.

Symptoms of atypical behavior may include:

Ways to manage

If you experience behavioral changes while taking oseltamivir oral capsule, tell your doctor right away. They’ll likely recommend stopping oseltamivir treatment.

Warnings for oseltamivir

Below are some factors you may want to discuss with your doctor before taking oseltamivir oral capsule.

Warnings

It may not be safe for you to take oseltamivir oral capsule if you have specific health conditions. These are sometimes called drug-condition interactions. Other things may also affect whether oseltamivir oral capsule is a safe treatment option for you.

Before taking oseltamivir oral capsule, tell your doctor about your health and the medications you take. Things to consider include:

  • kidney problems
  • difficulty swallowing pills
  • currently pregnant or planning to become pregnant
  • currently breastfeeding or planning to breastfeed
  • past allergic reaction to oseltamivir

Oseltamivir and pregnancy

In general, oseltamivir oral capsule is considered safe to take during pregnancy. That said, check with your doctor about whether they feel it’s safe for you specifically.

Oseltamivir and breastfeeding

It’s not known whether oseltamivir oral capsule should be taken while breastfeeding. If you’re breastfeeding or planning to do so, talk with your doctor before taking this medication.

Oseltamivir and alcohol

Oseltamivir oral capsule is not known to interact with alcohol.

But drinking alcohol while taking oseltamivir can worsen certain side effects, such as nausea and headache.

If you drink alcohol, talk with your doctor about whether it’s safe to consume it during your treatment with oseltamivir oral capsule.

Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.

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