Are there side effects or precautions when taking flu antivirals?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Flu antivirals, including oseltamivir (Tamiflu), can cause side effects ranging from mild to serious. Common side effects include nausea and vomiting, while less common but more serious risks include liver problems and neuropsychiatric changes such as confusion, mood shifts, or unusual behavior. Being aware of these potential effects helps you recognize warning signs early and seek timely medical care.

If you're experiencing flu symptoms or side effects from antiviral medication, don't guess about what's happening in your body. A free, instant, online symptom check can help you clarify your symptoms, identify possible causes, and understand when to consult a doctor—giving you clear, confident next steps in minutes.

Reviewed for medical accuracy: 07/20/2026

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Explanation

Flu antivirals, such as oseltamivir, are used to treat influenza, but they come with possible side effects and precautions.

Liver Concerns: According to the research by Mastroianni et al., there is an association between oseltamivir and acute hepatitis. This means that in some cases, taking oseltamivir might cause liver problems. It's important to monitor liver function if you are taking this medication.
Mental Health Effects: The study by Lan et al. highlights that oseltamivir can lead to worsening of psychiatric symptoms in some people. This includes changes in mood or behavior. If you or someone you know is experiencing mental health issues while on this medication, it's important to seek help. For immediate support, you can visit 988lifeline.org.
General Side Effects: The systematic review by Jefferson et al. provides a broad overview of oseltamivir's effects, indicating that while it is effective in treating flu, users should be aware of these side effects and take necessary precautions.

In summary, while flu antivirals can be helpful in treating influenza, being informed about potential side effects is crucial for safe use. If you're experiencing flu-like symptoms and want to better understand what might be causing them, try Ubie's free symptom checker to get personalized health insights in minutes.

(References)

Mastroianni A, Vangeli V, Greco S, Urso F, Greco F, Chidichimo L, & Mauro MV. (2021). Oseltamivir and acute hepatitis, reality association or .... Antiviral therapy, 35485329.
Lan CC, Liu CC, & Chen YS. (2015). Acute exacerbation of psychiatric symptoms during .... Journal of the Chinese Medical Association : JCMA, 25823677.
Jefferson T, Jones M, Doshi P, Spencer EA, Onakpoya I, & Heneghan CJ. (2014). Oseltamivir for influenza in adults and children: systematic .... BMJ (Clinical research ed.), 24811411.

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