Does Tamiflu Work for Flu Symptoms?

Tamiflu is the brand name for the flu-fighting medication, oseltamivir. It was approved by the FDA in 1999 and has gained popularity since then. It’s a first-choice option for treating the flu and is safe for most people (including infants) to take.

But does Tamiflu work? And just how effective is it? Let’s discuss what you can expect while taking Tamiflu.

What is Tamiflu?

Tamiflu (oseltamivir) is an oral antiviral medication that can treat influenza strains (types) A and B. These are the two main types of viruses that cause the seasonal flu. Specifically, it’s FDA approved to treat the flu in adults and children ages 2 weeks and older who developed symptoms less than 48 hours (2 days) ago.

In addition to treating the flu, Tamiflu can also be used for flu prevention in adults and children who are at least 1 year old. If you’ve recently been exposed to someone with the flu and have greater risks for severe illness, a healthcare professional may prescribe Tamiflu.

Tamiflu comes as 30 mg, 45 mg, and 75 mg capsules. It also comes as a 6 mg/mL oral liquid. The oral liquid can be helpful for measuring out an accurate children’s Tamiflu dosage. It may also be preferred if you have trouble swallowing pills.

Tamiflu isn’t the only FDA-approved flu antiviral that’s available. The inhaled medication Relenza (zanamivir) and the IV infusion Rapivab (peramivir) work similarly to Tamiflu. Xofluza (baloxavir marboxil) is the newest flu treatment. It’s an oral pill, but it works a bit differently from Tamiflu.

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How does Tamiflu work?

Tamiflu is a neuraminidase inhibitor. It stops neuraminidase — an enzyme (protein) found on the surface of the flu virus — from working. This enzyme plays an important role in how the flu virus multiplies inside your body.

When a flu virus infects a cell in your body, its goal is to make copies of itself to infect other cells. Neuraminidase helps the new copies of the virus leave one cell so they can travel to and infect other cells.

When Tamiflu blocks neuraminidase from working, the flu virus isn’t able to spread or make copies of itself as easily.

How long does it take for Tamiflu to work?

Tamiflu starts working to stop the flu virus from multiplying right away. But it can take a few days for you to start feeling better.

Overall, Tamiflu can decrease the severity of flu symptoms and shorten your illness by about 1 to 2 days. But in people ages 65 years and older who have chronic health conditions, Tamiflu may shave 2 to 3 days off total recovery time. Without treatment, flu symptoms typically last for about 3 to 7 days.

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How effective is Tamiflu?

Tamiflu’s effectiveness is most evident when people are in the hospital for the flu, have severe flu symptoms, or have a higher risk of flu-related complications. Higher-risk people include adults ages 65 and older, pregnant women, and people with certain health conditions, such as diabetes. The CDC lists these situations as “priority groups” who should take Tamiflu as soon as possible.

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Multiple small studies have shown that Tamiflu can help lower the risk of complications, such as pneumonia, in higher-risk groups. Results of some of those studies are listed below:

• Adults who were hospitalized due to the flu and took Tamiflu had a lower risk of being admitted to an intensive care unit (ICU) and dying from flu-related complications.

• Adults with chronic health conditions who were hospitalized for severe flu symptoms had a lower risk of dying from the flu after taking Tamiflu. The average age of study participants was 70 years old.

• Children who took Tamiflu were less likely to develop ear infections after recovering from the flu (a common flu complication for kids). They were also less likely to need antibiotics if they did develop ear infections.

• Children with asthma who took Tamiflu had better lung function and fewer asthma flare-ups.

But there’s also evidence to say Tamiflu may not provide significant benefit. A review of multiple studies found that the medication didn’t reduce the risk of flu-related hospital stays or complications. Many people included in this review were relatively young (mid-40s) and had a low risk of severe flu to begin with.

So is Tamiflu worth it? In some cases, yes. Research suggests Tamiflu likely has the greatest impact in higher-risk populations. This matches up with the CDC’s list of priority groups for the medication. Your prescriber should weigh the pros and cons of Tamiflu when deciding if you may benefit from it.

Keep in mind, Tamiflu works best when you take it at the optimal time: within 48 hours of your first flu symptoms. Some healthcare professionals may not prescribe it if you’ve had symptoms for longer than 48 hours, since it’s not as helpful in those cases.

The effectiveness of Tamiflu also depends on the specific flu strain you have. Some strains are resistant to flu antivirals. Your prescriber should take your location and local flu trends into account when choosing a flu antiviral for you.

Can you take Tamiflu if you’re pregnant?

Yes, Tamiflu is the first-choice flu treatment if you’re pregnant. It’s been well-studied for many years and isn’t known to raise the risk of birth defects. Starting Tamiflu within 48 hours of first feeling symptoms lowers your risk of dying from flu-related complications during pregnancy.

Your risk of hospitalization from the flu is higher when you’re pregnant. There’s also a greater risk of complications for your unborn baby when the flu is left untreated. So treating your infection quickly is important. And Tamiflu is the flu treatment with the most safety data available.

What are common side effects of Tamiflu?

The side effects of Tamiflu are generally mild. Most commonly, people experience:

• Nausea

• Vomiting

• Diarrhea

• Headache

Taking your doses with food can help lessen or prevent stomach-related side effects. Vomiting is more common in children than adults. And diarrhea is most often seen with infants. Let a healthcare professional know if any of the above side effects are excessive, severe, or persistent. This isn’t typical and should be addressed.

Serious side effects of Tamiflu are rare but possible. These include:

• Mental health changes in children

• Irregular heartbeats

• Seizures

• Serious confusion

In rare cases, Tamiflu can also cause dangerous skin reactions, such as Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN). The earliest signs of SJS and TEN are very similar to flu symptoms. So if you notice persistent fever and fatigue along with reddening of your skin or a red rash, let a healthcare professional know right away.

Is Tamiflu safe for children?

Yes, Tamiflu is safe for children. In fact, the American Academy of Pediatrics recommends it as the antiviral of choice for flu treatment in kids. Tamiflu is FDA approved for flu treatment in children 2 weeks of age or older. It’s also approved for flu prevention in children ages 1 year and older.

Children under 5 years old (particularly those under age 2) have a higher risk of severe illness and flu complications. Children of any age with other health conditions, such as diabetes or asthma, also have a higher risk. So, if your young child develops flu symptoms, it’s important to get them treatment right away.

As mentioned above, children and infants are more likely to experience some stomach-related side effects of Tamiflu. Your child’s pediatrician can help you decide if Tamiflu is right for your child.

How to save on Tamiflu

There are ways to save on Tamiflu, which is available as both a brand-name and generic medication. GoodRx can help you save over 80% off the average retail price of the generic version. Generic Tamiflu’s price at certain pharmacies is as low as $24.72 with a free GoodRx discount.

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Written by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Jennifer Gershman, PharmD, CPh, PACS

Jennifer Gershman, PharmD, is a licensed pharmacist in Florida. She has worked in the pharmacy industry for more than 15 years and is currently a medical writer.

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