Tamiflu (Oseltamivir): What It Does and How to Use It

Tamiflu is a prescription antiviral that can shorten flu symptoms if you start it early. Clinical trials show it tends to reduce symptom time by about one day when begun within 48 hours of feeling sick. That doesn’t sound huge, but for high-risk people—young kids, older adults, pregnant people, or anyone with chronic illness—those saved hours can matter.

How to take Tamiflu

For adults the usual treatment dose is 75 mg twice a day for five days. There’s also a preventive option—often one 75 mg tablet once daily for about 10 days after exposure, but your doctor will decide. Kids get doses based on weight, so don’t guess—ask a pediatrician. Start as soon as possible; after 48 hours the benefit drops sharply.

If you have kidney problems, dosing needs adjustment. Also, if you vomit right after a dose, call your provider; they may recommend repeating it. Don’t stop other supportive care: rest, fluids, and over‑the‑counter fever reducers as advised by a clinician.

Safety, side effects, and buying tips

Common side effects are nausea, vomiting, and sometimes headache. Taking Tamiflu with food often reduces nausea. Rarely, children and teens have reported confusion or unusual behavior—watch for sudden mood or mental changes and seek help if they happen. Drug interactions are limited but include drugs like probenecid that raise oseltamivir levels.

Pregnant people and breastfeeding parents: many guidelines support using antivirals for confirmed flu when the benefits outweigh risks, because flu can be risky in pregnancy. Still, check with your provider to weigh options for your situation.

Only buy Tamiflu from licensed pharmacies. It’s a prescription medicine in most countries, so a site that sells it without asking for a prescription is a red flag. Look for a pharmacy license, clear contact info, and secure payment. If you use an online service, choose one that requires an online consult or uploads a real prescription.

If you’re trying to prevent flu in a close contact at home, talk to your doctor about whether prophylaxis makes sense—sometimes vaccination plus monitoring is the better route. And remember: Tamiflu isn’t a substitute for the seasonal flu vaccine; the vaccine reduces your risk of getting the flu in the first place.

Quick checklist: start Tamiflu within 48 hours if possible; follow weight-based dosing for kids; expect mild nausea and watch for strange behavior in young people; buy only from licensed pharmacies with a prescription.