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Can oseltamivir (Tamiflu) prevent complications?

Last Update: November 3, 2016; Next update: 2019.

In some groups of people, having the flu can sometimes lead to serious complications such as pneumonia. Drugs like oseltamivir (trade name: Tamiflu) aim to prevent things from turning serious. But research has only shown that taking oseltamivir might make general flu symptoms go away a bit sooner.

Influenza or ‘the flu’ is a viral infection of the upper respiratory tract (a disease of the airways). It can cause a wide range of symptoms, including fever, chills, muscle ache, fatigue, headache, sore throat, a cough and a blocked nose.

Most people who come down with the flu get better within a week. But they may have a cough and feel unwell for about one to two weeks after that.

Children, older people and people with chronic medical conditions are at greater risk of getting very sick if they have the flu. They are more likely to have complications like pneumonia. The flu can be fatal for these groups of people if they develop complications. But people who are otherwise healthy are very unlikely to die of the flu.

Effect and use of oseltamivir (Tamiflu)

Just like with most common colds, antibiotics also do not help if someone has the flu. They are not effective against viruses, only against bacteria. But there are drugs that prevent viruses from spreading in the body. They are called antivirals, and oseltamivir is one of them. This drug is available in Germany under the trade name Tamiflu, and is prescription-only. It is hoped that it will stop people becoming very ill and having serious complications.

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.

Osteltamivir needs to be taken within 48 hours after the flu symptoms start. It someone has already had symptoms for longer, it will not have an effect on the course of their flu.

Research on treatment

Researchers at the Cochrane Collaboration, an international research network, looked for studies on treatment with oseltamivir. Although oseltamivir has been tested in many different studies, it was still difficult to accurately assess its advantages and disadvantages. This is because many of the results of these studies were only partially published, or not at all. The manufacturer of Tamiflu and the US and European regulatory authorities have now released previously unpublished data. In their latest analysis, the researchers at the Cochrane Collaboration assessed the results of 20 studies in which almost 10,000 children and adults took part.

The researchers did not 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 last 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 who took Tamiflu, and by about a day in children who took Tamiflu.

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.

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

Research on prevention

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: Around 3 out of 100 participants who took oseltamivir as a preventive measure were not protected from infection, but were protected from flu symptoms.

But side effects were common in these studies too: Around 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.

Hygiene measures such as regularly washing your hands are still one of the best ways to prevent infection.


  • Ebell MH, Call M, Shinholser J. Effectiveness of oseltamivir in adults: a meta-analysis of published and unpublished clinical trials. Fam Pract 2013; 30(2): 125-133. [PubMed: 22997224]
  • Jefferson T, Jones MA, Doshi P, Del Mar CB, Hama R, Thompson MJ et al. Neuraminidase inhibitors for preventing and treating influenza in healthy adults and children. Cochrane Database Syst Rev 2014; (4): CD008965. [PubMed: 22258996]
  • World Health Organization (WHO). Antiviral drugs for pandemic (H1N1) 2009: definitions and use. Geneva: WHO. December 22, 2009.
  • IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

    Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. We do not offer individual consultations.

    Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

© IQWiG (Institute for Quality and Efficiency in Health Care)

IQWiG (Institute for Quality and Efficiency in Health Care)

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