Tamiflu (Oseltamivir) Capsules for Influenza
Tamiflu is an oral neuraminidase inhibitor containing oseltamivir. It is used in adults and children for treatment and prophylaxis of influenza A and B, with greatest benefit when started within 48 hours of symptom onset.
- Active ingredients
- Oseltamivir
- Manufacturer
- Roche
- Dosage forms
- capsule, oral suspension
- Available dosages
- 30mg, 45mg, 75mg
- Category
- Antiviral Medications
What is it?
Tamiflu is the original brand of oseltamivir, marketed by Roche since its approval in 1999. It is supplied as oral capsules at 30mg, 45mg and 75mg, and as oral suspension. Tamiflu is dispensed only on prescription and is part of the World Health Organization List of Essential Medicines. Many governments have stockpiled Tamiflu for pandemic preparedness, although the magnitude of clinical benefit in routine seasonal influenza has been debated in evidence reviews.
Active ingredients
Each capsule contains oseltamivir (as the phosphate) as the sole active ingredient at 30mg, 45mg or 75mg of oseltamivir base. Oseltamivir is a neuraminidase inhibitor that blocks the release of newly formed influenza virions from infected cells.
Forms and dosages
Tamiflu is administered orally with or without food, ideally with food to reduce gastrointestinal side effects. According to the prescribing information, the usual adult dose for treatment is 75mg twice daily for 5 days, and for post-exposure prophylaxis is 75mg once daily for 7-10 days. Paediatric dosing is weight-based using the oral suspension. Substantial dose reduction is required in renal impairment.
Indications
Tamiflu is approved in adults and children for the treatment of acute uncomplicated influenza A and B when started within 48 hours of symptom onset, and for post-exposure prophylaxis of influenza A and B in patients aged 1 year and older. According to international guidelines, treatment is recommended for patients at high risk of complications, those requiring hospitalisation and severe progressive disease. Routine treatment of low-risk patients with mild influenza is more controversial.
How it works
Oseltamivir is a prodrug rapidly hydrolysed by hepatic esterases to the active metabolite oseltamivir carboxylate, which selectively inhibits the neuraminidase enzyme on the surface of influenza A and B viruses. Neuraminidase is required for the release of newly formed virions from infected cells and for spread of virus through the respiratory mucus, so its inhibition reduces viral replication and clinical illness when treatment is started early.
Frequently asked questions
When is Tamiflu most effective? ▾
Tamiflu is most effective when started within 48 hours of influenza symptom onset, and ideally within 24 hours. Earlier treatment provides greater reductions in symptom duration. According to international guidelines, treatment should still be considered after 48 hours in patients hospitalised with severe disease or at high risk of complications, where the benefits may persist beyond the early window. The prescriber should evaluate the indication.
Can Tamiflu prevent influenza after exposure? ▾
Yes. Post-exposure prophylaxis with Tamiflu is approved for patients aged 1 year and older after close contact with a confirmed or suspected case of influenza, particularly during outbreaks in households or institutional settings. According to the prescribing information, prophylaxis is typically given for 7-10 days following exposure. Vaccination remains the primary preventive strategy and should not be replaced by antiviral prophylaxis.
Does Tamiflu work for COVID-19? ▾
No. Oseltamivir is a neuraminidase inhibitor active only against influenza A and B viruses. It does not have activity against SARS-CoV-2 (the virus causing COVID-19) or other respiratory viruses such as respiratory syncytial virus or rhinovirus. According to the prescribing information and current clinical guidelines, Tamiflu should not be used for non-influenza respiratory infections. Specific antivirals exist for COVID-19 and should be discussed with a clinician.
Why must the dose be reduced in kidney disease? ▾
Oseltamivir carboxylate is excreted unchanged in urine, so renal impairment substantially increases plasma concentrations and the risk of adverse effects. According to the prescribing information, the dose is reduced based on creatinine clearance, with specific recommendations for patients on haemodialysis and peritoneal dialysis. Renal function should be assessed before treatment, particularly in older adults.
What are the main contraindications for Tamiflu? ▾
Tamiflu is contraindicated in known hypersensitivity to oseltamivir or its excipients. Caution is required in renal impairment (with mandatory dose adjustment), in younger children (where dosing is weight-based), in pregnancy and breastfeeding (where benefits typically outweigh risks), and in patients with previous neuropsychiatric reactions. According to the prescribing information, the medical history must be reviewed by a clinician before any prescription.
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The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.