This medicine contains the active ingredient oseltamivir phosphate, which is a type of medicine called a neuraminidase inhibitor. It is used to treat and prevent infection with the influenza virus (flu).

Influenza is caused by a highly contagious virus which affects the respiratory system. The virus is passed from one person to another by coughing and sneezing. When the virus enters the body it invades cells, where it replicates to form lots of new virus particles.

These new copies of the virus are then released from the cells and move on to infect adjoining cells, where the process is repeated. After a couple of days a sufficient number of cells have been infected so that the patient feels flu symptoms such as headache, fever and general aches and pains, which continue for about a week until the bodys immune system kills the virus.

In order to leave one cell and infect another, the influenza virus uses a chemical helper that is found on its surface. This substance is an enzyme called neuraminidase, and without it the newly formed virus particles cannot leave the infected cells.

Oseltamivir works by binding to the neuraminidase on the surface of the virus particles, and stopping it from working. When the neuraminidase helper is blocked in this way it means that newly formed viral particles cannot be released from the infected cells. This prevents the flu virus from spreading and infecting other cells.

Oseltamivir therefore confines the infection to a smaller area. This makes the symptoms of the infection less severe and also makes it is easier for the bodys immune system to kill the virus. The medicine has been shown to reduce the duration of the illness by approximately one day, and to reduce the risk of developing flu-related complications, such as chest infections that require antibiotics.

This medicine is only effective against the influenza virus. It will not work against illnesses that are caused by other agents.

At the moment it is not known whether this medicine will be effective at treating or preventing flu if you have a weakened immune system, for example due to HIV infection or treatment with immunosuppressant medicines such as chemotherapy or corticosteroids. It is also not known if it will be effective for treating flu in people with chronic heart disease or respiratory disease, or in people with medical conditions that are sufficiently severe or unstable to potentially require admission to hospital.

The National Institute of Clinical Excellence (NICE) has recommended that oseltamivir should not be prescribed to people who have flu who are otherwise healthy. They recommend that it is only used to treat people who are at risk of developing complications from flu. These people are those aged over 65 years; and those with chronic respiratory disease, eg asthma or COPD, significant heart disease, long-term kidney disease, diabetes, or a poorly functioning immune system. In addition, it should only be used in these people if they can start treatment within two days of the onset of symptoms, and if the influenza virus is known to be circulating in the community.


What is it used for?

• Prevention of flu (influenza) in adults and adolescents aged 13 years and over who have been in contact with someone diagnosed with flu when it is circulating in the community
  
  
• Treatment of flu (influenza) in adults and children over one year of age when the influenza virus is circulating in the community
  
  

• This medicine is not recommended for people with severely decreased kidney function.
  
  
• The safety and efficacy of this medicine for treating influenza in children under one year of age has not been established. In addition, the safety and efficacy of this medicine for preventing influenza in children aged 12 years and under has not been established.
  
  
• This medicine should not be used as a substitute for being vaccinated against flu. People who are at risk of complications if they contract flu should continue to have a yearly flu-vaccination to prevent the illness. These people include the elderly, people with chronic heart or lung disease, and people with a weakened immune system.
  
  
• Tamiflu suspension contains sorbitol and may not be suitable for people with a hereditary intolerance to fructose. Tamiflu capsules do not contain sorbitol.
  
  

• Decreased kidney function
  
  

• Allergy to any ingredient
  
  

• The safety of this medicine for use during pregnancy has not been established. It is not recommended for use in pregnancy unless considered essential by your doctor. Seek medical advice from your doctor.
  
  
• It is not known if this medicine passes into breast milk. It is not recommended for use during breastfeeding unless considered essential by your doctor. Seek medical advice from your doctor.
  
  

• Rash
  
  
• Abdominal pain
  
  
• Vomiting
  
  
• Nausea