Tamiflu: Should You Worry About Side Effects?

If you have the flu, this antiviral drug can be a big help—but some serious side effects have been reported.

hands opening a pill pack

Medically reviewed in January 2021

Updated on February 1, 2021

Though COVID-19 has dominated headlines since early 2020, you shouldn’t forget influenza. The flu remains a big-time health concern for healthcare providers and patients year in and year out. You can catch the illness any time of year, but flu season typically begins in October and peaks between the months of December and February. And as you likely know, the flu can cause some pesky symptoms, such as a fever, cough, sore throat and fatigue. It can also lead to more serious complications, like pneumonia.   

If you become sick with the flu, speak with a healthcare provider as soon as possible. You can ask for an antiviral drug prescription, which could shorten the misery. Medication is most effective for people who take it within 48 hours of having symptoms.

That said, you may have heard some scary stuff about the most popular antiviral, Tamiflu (oseltamivir). There have been some reports over the years that it may spark hallucinations and unusual, even life-threatening behavior.

Are side effects like these really something to worry about? Here's what you should know about this antiviral medication—and how to put it all into perspective.

Your antiviral options
Four antiviral drugs to treat the flu are approved by the U.S. Food and Drug Administration (FDA) and recommended by the Centers for Disease Control and Prevention (CDC). They are:

  • Tamiflu (oseltamivir)
  • Relenza (zanamivir)
  • Rapivab (peramivir)
  • Xofluza (baloxavir marboxil)

Of these, Tamiflu is the most popular, according to Amesh Adalja, MD, a senior scholar at the Johns Hopkins Center for Health Security and a spokesperson for the Infectious Diseases Society of America. It can be given in liquid or capsule form. A generic version of oseltamivir is also available.

Relenza comes in inhaler form and can be cumbersome to use, he says. Rapivab is given intravenously, usually to someone so sick they can't take medicine by mouth. Xofluza is a pill given as a single dose. Two other antiviral drugs, amantadine (generic) and rimantadine (Flumadine and generic versions) have been approved by the FDA, but the CDC doesn't currently recommend them, as they don't work well against the flu viruses that have been circulating in recent years.

What Tamiflu does
Tamiflu works by blocking the action of an enzyme on the surface of the flu virus, restraining the virus from spreading to other cells, according to Genentech, its maker.

Tamiflu isn't just meant for people who want to shorten the time they’re sick—though it can reduce the course of the flu by about a day. It is recommended in particular for those at risk of complications of the flu. This includes young children, older adults, nursing home residents and those with other major health issues, like heart disease or diabetes.

The drug may help prevent ear infections in children, for example. It may also help avert pneumonia—and even death—in adults, according to the CDC. Healthcare providers use their judgment in prescribing it to otherwise healthy people.

The lowdown on side effects
"In general, Tamiflu is a well-tolerated drug," Dr. Adalja says. Nausea and vomiting are the most common side effects; you can be given additional medicine to ease the vomiting. There have, however, been rare reports of hallucinations, confusion and other unusual behavior, which are of concern to patients and providers.

In 2018, an Indiana family reportedly blamed the drug for the suicide of their teenaged son. That same year, a family in Texas told the media that their daughter, after taking Tamiflu, began hallucinating and was about to jump out a window when her mother rescued her.

Earlier, in 2005, the FDA reviewed reports of teens in Japan who experienced similar symptoms; these included reports of 12 deaths. The agency concluded that the evidence could not prove the drug was responsible, and Genentech says there hasn't been a connection established between Tamiflu and the events.

Genentech warns that those with flu, especially children and teens, may be at an increased risk of seizures, confusion or abnormal behavior soon after they get sick. These side effects may occur after starting to take Tamiflu, or they may start when the patient has the flu but doesn't take Tamiflu, the company has noted.

Adalja agrees that no cause and effect can be proven. It is possible, he says, that something about having the flu by itself may trigger these reactions in some people, with members of younger age groups perhaps being more vulnerable.

What's more, Adalja says he has never seen cases of psychiatric side effects from Tamiflu. "I am a pretty liberal prescriber of Tamiflu," he adds. ''We do know Tamiflu is very well tolerated by the vast majority of people." In fact, in a March 2018 study published in the Annals of Family Medicine, researchers found no connection between Tamiflu and suicide in pediatric patients.

Even so, Adalja says, if you take the drug, you should be sure someone watches you for signs of abnormal behavior. If any worrisome or unusual behavior occurs, such as talk of self-harm, get medical help right away. You can also call the National Suicide Prevention Lifeline at 800-273-8255 or text HOME to 741741 to reach the Crisis Text Line.

Article sources open article sources

Centers for Disease Control and Prevention. “Weekly U.S. Influenza Surveillance Report.” 2021. Accessed January 14, 2021.
WNDU.com. “Indiana family believes Tamiflu side effect may have caused teen suicide.” January 31, 2018.
ABC11.com. “6-year-old Texas girl suffered rare side effects after taking Tamiflu.” January 15, 2018.
Centers for Disease Control and Prevention. “Influenza Antiviral Medications.” October 26, 2020. Accessed January 14, 2021.
Centers for Disease Control and Prevention. “Influenza Antiviral Medications: Summary for Clinicians.” November 30, 2020. Accessed January 14, 2021.
Tamiflu.com. “Taking Tamiflu.” 2021. Accessed January 14, 2021.
U.S. Food & Drug Administration. “The FDA approves first generic version of widely used influenza drug, Tamiflu.” August 4, 2016. Accessed January 14, 2021.
Gene.com. “Tamiflu (Oseltamivir Phosphate).” 2021. Accessed January 14, 2021.
Gene.com. “Tamiflu Prescribing Information.” August 2019. Accessed January 14, 2021.
U.S. Food & Drug Administration. “Tamiflu Pediatric Adverse Events: Questions and Answers.” December 7, 2015.
R Harrington, S Adimadhyam, et al. “The Relationship Between Oseltamivir and Suicide in Pediatric Patients.” Annals of Family Medicine. March 2018, 16 (2) 145-148.
U.S. Food & Drug Administration. “Influenza (Flu) Antiviral Drugs and Related Information.” October 26, 2020. Accessed February 1, 2021.
Bradley Blackburn. “Tamiflu sent son into rage, Garland mom says.” WFAA.com. February 14, 2018.
The Medical Letter. “Antiviral Drugs for Influenza for 2020-2021.” December 1, 2020. Accessed February 1, 2021.
MedlinePlus. “Zanamivir Oral Inhalation.” January 15, 2018. Accessed February 1, 2021.
Rapivab.com. “Dosing & Administration.” 2021. Accessed February 1, 2021.
Xofluza.com. “For Patients and Caregivers.” 2021. Accessed February 1, 2021.
MedlinePlus. “Amantadine.” May 15, 2018. Accessed February 1, 2021.
Medscape. “Rimantadine (Rx).” 2021. Accessed February 1, 2021.
Centers for Disease Control and Prevention. “Children and Flu Antiviral Drugs.” September 15, 2020. Accessed February 1, 2021.
U.S. Food & Drug Administration/Center for Drug Evaluation and Research. “Approval Package for Tamiflu/Oseltamivir Phosphate.” December 21, 2005. Accessed February 1, 2021.
National Suicide Prevention Lifeline. “Help Someone Else.” 2021. Accessed February 1, 2021.

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