Oseltamivir (Tamiflu) for the flu: timing and label doses

The World Health Organization describes influenza as usually starting suddenly, with fever, a dry cough, headache, and muscle and joint pain. Most people recover within about a week.

The symptoms overlap with a cold, so it is hard to tell them apart yourself. If you are unsure, or you are in a higher-risk group, ask a doctor or pharmacist.

Tamiflu is a brand of oseltamivir, an antiviral for influenza A and B. The US label covers treatment and prevention after contact with a case. It is not for other infections.

The shop lists Tamiflu 75 and Oselvir-75, another brand whose maker lists oseltamivir 75 mg. The details below follow the US Tamiflu label as a reference. For any other brand or pack, follow the leaflet inside that box.

The label says to begin treatment within 48 hours of the first flu symptoms. Early matters. If more time has passed, ask a doctor whether it is still suitable.

Adults and teenagers aged 13 and over with normal kidney function: 75 mg twice daily for 5 days, with or without food.

Children aged 1 to 12 years are dosed by weight (per dose, twice daily for 5 days):

Infants from 2 weeks to under 1 year: 3 mg per kg twice daily. Doses below 75 mg need a lower-strength product or the oral suspension, not a 75 mg capsule.

Reduced kidney function means the dose is adjusted using the label's table and kidney test results, and the label does not recommend it for end-stage kidney disease without dialysis. Child and kidney dosing here is a general summary. A doctor or pharmacist sets the actual dose.

The most common effects in treatment studies were nausea, vomiting and headache. In prevention studies, pain was also reported.

Cautions from the label:

• Do not use after a serious allergic reaction to oseltamivir or its ingredients.
• Severe skin reactions or allergy: stop and get urgent help.
• People with flu, especially children, can have confusion or unusual behaviour early in the illness. Watch for it.
• Avoid the nasal-spray live flu vaccine from 2 weeks before to 48 hours after Tamiflu unless medically needed. Injected flu vaccine can be given at any time.

No. The label says Tamiflu is not a substitute for yearly flu vaccination, and WHO says vaccination is the best way to prevent influenza.

• Before starting, if the patient is a child, pregnant, older, or has a long-term condition, so the dose can be set properly.
• If you have kidney disease or are unsure about the dose.
• Severe rash, swollen face, trouble breathing, confusion or unusual behaviour.
• Symptoms get worse after starting, or are no better after several days.