Can oseltamivir (Tamiflu) prevent complications of the flu?

Just like with most common colds, antibiotics don't help if someone has the flu. That's because they are only effective against bacteria, not viruses. But there are drugs that prevent viruses from spreading in the body. They are called antivirals, and oseltamivir is one of them. It is available in Germany under the trade name Tamiflu, and is prescription-only.

Oseltamivir belongs to a group of drugs called neuraminidase inhibitors. These drugs aim to block a protein called neuraminidase. Flu viruses need neuraminidase in order to spread in the body. It is hoped that using these medications will stop people becoming very ill and having serious complications.

Oseltamivir needs to be taken within 48 hours after the flu symptoms start. It will not have any effect on the course of the flu if you take it later than that.

Researchers at the Cochrane Collaboration (an international research network) looked at the results of a total of 20 studies in which almost 10,000 children and adults took part.

The researchers didn't find any evidence that oseltamivir would be able to prevent serious cases and complications in the event of a flu epidemic. They only found proof that Tamiflu can shorten the duration of flu symptoms a little:

• Without Tamiflu, symptoms lasted 7 days on average in otherwise healthy children and adults.
• With Tamiflu, the duration of symptoms was shortened by a number of hours (from 7 to 6.3 days) in adults, and by about one day in children.

But the medication had no effect in children with asthma. It is unclear whether people who have the flu are less contagious after taking Tamiflu.

A recent analysis of both older and newer studies on oseltamivir suggests that treatment with oseltamivir leads to fewer complications, such as middle ear infection.

The most common side effects of oseltamivir are vomiting and nausea. 4 out of 100 people in the studies had these side effects.

Some studies looked into whether taking oseltamivir can protect people from the flu. This is an important question for relatives and other people who have temporary but intensive contact with infected people. The studies showed that the drug has a slight protective effect: About 3 out of 100 participants who took oseltamivir as a preventive measure were protected from flu symptoms, but not from infection.

Side effects were common in these studies too, though: About 2 out of 100 people had headaches after taking oseltamivir, and 3 out of 100 experienced nausea. The studies also suggest that oseltamivir can – in rare cases – cause kidney problems and psychiatric problems such as hallucinations, depression or confusion. The U.S. drug agency FDA therefore recommends that people look out for unusual changes in behavior and seek medical advice if necessary.