Tamiflu (oseltamivir) is a prescription antiviral medication used to treat flu symptoms and prevent influenza in specific situations. Its preventive use requires medical evaluation.
How Tamiflu Acts Against Influenza
Tamiflu belongs to a class of medications known as neuraminidase inhibitors. Neuraminidase is an enzyme on the influenza virus surface that helps new viral particles detach from infected host cells after replication. Tamiflu works by blocking this enzyme’s activity. This prevents the release of new viral particles from infected cells, limiting the virus’s spread within the body.
Criteria for Preventive Use
Tamiflu is not for general prevention, but targets specific high-risk scenarios. Influenza vaccination remains the most effective and primary method for preventing the flu. Preventive use of Tamiflu (prophylaxis) requires a doctor’s prescription and assessment.
Post-exposure prophylaxis is a common preventive use, taken after exposure to confirmed or highly suspected influenza. This is often recommended for close contacts, such as household members or caregivers, especially if the exposed individual is at high risk for flu complications. High-risk individuals include children under two years old, adults 65 years and older, pregnant individuals, and those with chronic medical conditions like asthma, diabetes, heart disease, or weakened immune systems. Starting Tamiflu within 48 hours of exposure can help reduce the chance of developing the flu.
Pre-exposure prophylaxis is taking Tamiflu before potential exposure. This may be considered during an influenza outbreak in a closed setting, such as a long-term care facility, particularly for residents or staff who are unvaccinated or for whom the vaccine may be less effective. In certain situations, it can also be considered for high-risk individuals who cannot be vaccinated or for whom the vaccine is contraindicated, especially during periods of high influenza activity. This type of preventive use is less common and relies on specific medical guidance.
Administration Guidelines for Prophylaxis
When Tamiflu is prescribed for prevention, the dosage typically differs from that used for treatment. For adults and adolescents 13 years and older, the usual preventive dose is 75 mg taken orally once daily. For children, the dosage is determined by their weight.
The duration of prophylactic treatment varies. For post-exposure prophylaxis after close contact with an infected individual, it is typically taken for at least 10 days. If there is an ongoing community outbreak or continued exposure, the medication might be taken for up to six weeks. In some cases, such as for immunocompromised patients, the duration can extend up to 12 weeks.
Common side effects include nausea, vomiting, and headache. These are often mild and may be lessened if the medication is taken with food. It is important to take Tamiflu exactly as prescribed, even if symptoms do not develop. Tamiflu for prevention is not a substitute for the annual flu vaccine and should be used alongside other preventive measures, such as frequent handwashing.