Drug Info

Does Tamiflu work?

Avatar By | December 3, 2019
Medically reviewed by Karen Berger, Pharm.D.

It’s flu season, and that means this pesky seasonal infection is on the rise—spreading fever, chills, aches, pains, cough, and sore throat. But just because it infects many people annually, it’s not a virus to take lightly. It can have serious complications, especially for certain populations. If you’re in a high risk group, your healthcare provider might prescribe Tamiflu (oseltamivir) at the first sign of symptoms. Three physicians explain Tamiflu effectiveness, and how to know if you should take it.

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What is Tamiflu?

Tamiflu is an antiviral drug that blocks influenza types A and B by attacking the virus and stopping it from multiplying, according to the Food and Drug Administration (FDA). Tamiflu does not work on other viruses.

Preparation—read: getting an annual flu vaccine—is the best way to avoid catching this respiratory infection. Tamiflu is sometimes used to prevent flu for people exposed to the virus, but it is not an effective substitute for the immunization.

If you do get the flu, Tamiflu can reduce the intensity of symptoms and reduce the amount of time that you feel sick. 

RELATED: How to get a discounted (or free) flu shot

How effective is Tamiflu?

Tamiflu can reduce complications of the flu (such as pneumonia) by 44%, and the risk of hospitalization by 63% when taken in the first 48 hours after contracting the virus, according to the makers of Tamiflu. When used to prevent the flu in people exposed to the virus, it reduced the probability of becoming sick by up to 55%, says the National Center for Health Research.

“Tamiflu is not a cure for the flu, It won’t completely eliminate all of your symptoms. But it usually shortens the duration of the symptoms,” explained Michael Carnathan, MD, a family physician in Bethlehem, Pennsylvania. He stressed, “It is most effective when started within the first 24 to 48 hours after the first symptom. Don’t be afraid to contact your doctor at the first sign of a fever and body aches.” 

“Flu symptoms often appear suddenly and make you feel as if you were hit by a Mack truck,” stated Genevieve Brauning, MD. You might wake up with a fever and aches and pains, or you might come home from work not feeling well. “Because there is only a short window of time to take Tamiflu so it is effective, it is best to contact your doctor immediately. After 48 hours, it might not be worthwhile to take Tamiflu.” And, you’re still contagious after taking Tamiflu. Meaning, you can transmit the virus to others.

The flu is one time when it is better to call than to adopt a “wait and see” attitude. It is better to be told you don’t have the flu than to hold off calling and suffer through a week or more of debilitating symptoms. 

Is Tamiflu safe?

Tamiflu is very safe, according to Dr. Carnathan. And, it’s effective for patients as young as two weeks old. However, you should always discuss the benefits and risks of taking Tamiflu with your healthcare provider.

Tamiflu can have side effects (usually occurring within the first two days), and for some people, these can be worse than having the flu, according to Dr. Brauning. The most common side effects include:

  • Abdominal pain
  • Nausea
  • Vomiting
  • Headache 

Even though the FDA has approved Tamiflu for young children, Dr. Brauning is always cautious when prescribing it for children because of the side effects.

Who should (and shouldn’t) take Tamiflu?

Tamiflu is best for patients who are at high risk of developing severe complications from the flu virus. This includes very young children, the elderly, immunocompromised patients, patients with diabetes, heart disease, asthma, and other chronic diseases, and nursing home residents.  

Patients with mild to moderate liver impairment can safely take Tamiflu. In patients with mild kidney issues or with end-stage renal disease and on dialysis, the dose of Tamiflu will likely be adjusted. But, Tamiflu is not recommended for people who have end-stage renal disease and are not on dialysis. Patients with severe liver disease should speak with their doctor as to whether or not it is safe to take Tamiflu, according to Dr. Carnathan. 

Is Tamiflu safe if you are pregnant?

“Women who are pregnant should seek medical help at the first sign of flu because they are at high risk of complications from the flu,” according to Alyse Kelly-Jones, MD. The flu is risky for expectant mothers and their babies. “It can be fatal during pregnancy, and it also increases the risk of preterm labor, which puts the baby at risk of health complications,” she further explained. 

Because there are no well-controlled studies in pregnant women, Tamiflu will only be prescribed if your doctor feels that the benefits outweigh the potential risks to the fetus. However, at the first sign of symptoms, or if you are running a fever, you should contact your primary care provider immediately. Because many offices prefer not to have someone with the flu in the waiting room (where they can spread it to other people), you may receive treatment over the phone. If you are experiencing additional symptoms such as shortness of breath, chest pain, or dehydration, consider emergency treatment to see if inpatient care is required.

When to call your doctor

Symptoms of the flu include fever, chills, body aches, weakness, and may include a headache or cough. While the common cold comes on gradually, flu symptoms appear quickly. If you experience any of these symptoms or have been exposed to someone diagnosed with the flu, you should call your physician’s office to see if Tamiflu is right for you. Remember, the first 48 hours are crucial for the most effective flu treatment, so do not hesitate to make that call.