Tamiflu (oseltamivir): when it helps and how it is prescribed

Oseltamivir is an antiviral medicine; Tamiflu is its brand name, and a generic version also exists. According to MedlinePlus, it is used to treat influenza (flu) in people whose symptoms began in the last 48 hours and, in some cases, to help prevent flu in someone who had close contact with a person who has it. It comes as capsules and as an oral liquid.

It is not an antibiotic: antibiotics treat bacteria, and flu is caused by a virus. It is also not a vaccine. Oseltamivir acts on the flu virus so it multiplies less; it does not replace the yearly flu shot. To understand when antibiotics are needed, read antibiotics by telehealth.

The CDC recommends four FDA-approved flu antivirals, and oseltamivir is the most widely used. According to the CDC, treatment gives the most benefit when started within the first two days of illness: in otherwise healthy people it can shorten the illness by about a day and, in some, reduce complications such as pneumonia or ear infections.

Here is what to know about timing:

The CDC recommends early antiviral treatment for people at higher risk of complications. Higher-risk groups include:

In much of the United States, flu rises in the fall and winter. In tropical places such as Puerto Rico, the CDC notes that flu can circulate all year, and cases often climb as the end of the year approaches. That is why it helps to know ahead of time what to do: if fever, body aches and a cough hit you suddenly, do not wait to see if it passes, because every day counts against the 48-hour window.

The best protection is still the yearly flu vaccine. Oseltamivir does not replace it. If you have not been vaccinated, ask your pharmacy or your doctor. In the meantime, wash your hands, cover your cough and stay home if you have a fever.

To treat the flu, oseltamivir is taken as a short course: according to the FDA label, usually five days, in the amount your doctor sets based on your age, weight and how your kidneys work. This guide does not give doses: the prescription carries the exact instructions.

According to MedlinePlus, these points help you take it well:

According to MedlinePlus and the FDA label, the most common side effects are nausea and vomiting, and sometimes headache or stomach pain. Taking it with food often helps. These effects are usually mild and pass; if you cannot keep the medicine down because of vomiting, tell the doctor.

These are rare but need attention:

Oseltamivir acts against the flu virus. It does not work on other viruses that cause similar symptoms:

For fever and body aches, acetaminophen or ibuprofen relieve symptoms but do not treat the virus. Oseltamivir does act on the virus and requires a prescription. See which pain reliever is better for you in ibuprofen and naproxen. Never give aspirin to a child or teenager with the flu.

At the visit, the doctor asks when symptoms began, what fever you have had, whether you were around someone with the flu, whether you have asthma, diabetes, pregnancy or another risk factor, and what medicines you take. With that she decides whether oseltamivir is right for you or another plan is better. If a test is needed, we give you the lab order.

If appropriate, treatment is coordinated with your pharmacy. If you need a doctor’s note for work or school, it is included after the visit. For the full picture of symptoms, read the guide to flu (influenza).

If you have the flu and notice any of these signs, call 911 or go to the emergency room. See when to go to the ER.