Oseltamivir vs Acyclovir: side-by-side comparison
Oseltamivir (Neuraminidase inhibitor) and Acyclovir (Nucleoside antiviral) belong to different therapeutic classes and are rarely substitutes for each other. The comparison is useful when a single patient is weighing both options for adjacent or overlapping needs.
| Property | Oseltamivir | Acyclovir |
|---|---|---|
| Therapeutic class | Neuraminidase inhibitor | Nucleoside antiviral |
| CAS | 196618-13-0 | 59277-89-3 |
| ATC | J05AH02 | J05AB01 |
| Molecular weight | 312.40 g/mol | 225.21 g/mol |
| Brands with this active ingredient | 1 | 1 |
What they share
Oseltamivir and Acyclovir share the common regulatory framework for prescription active ingredients, bioequivalence standards for generics, and pharmacist oversight. Beyond that, points in common are limited.
Key differences
Oseltamivir acts by a different mechanism than Acyclovir, with indications that barely overlap. Comparing the two is useful when a clinician has mentioned both in the same context or the patient wants to understand why one was prescribed instead of the other.
Mechanisms compared
Oseltamivir: 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. Acyclovir: Acyclovir is a guanosine analogue selectively phosphorylated by viral thymidine kinase to its monophosphate form, then by cellular kinases to acyclovir triphosphate.
Indications compared
Oseltamivir: Oseltamivir 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… Acyclovir: Acyclovir is approved in adults and children for the treatment of herpes simplex virus infections, including genital herpes (initial and recurrent episodes), suppressive therapy of recurrent genital herpes, herpes labial…
Safety profile
Oseltamivir: Common adverse effects include nausea and vomiting, particularly when taken without food. Acyclovir: Common adverse effects include nausea, headache, dizziness and skin rash.
Frequently asked questions
Is Oseltamivir better than Acyclovir? ▾
Oseltamivir and Acyclovir are not "better or worse" — they treat different things. The sensible question is which fits your specific need.
Can Oseltamivir and Acyclovir be combined? ▾
Whether they can be combined depends on the indications and the interaction profile of each. If both are in a single prescription, the prescriber has weighed it; in self-medication they should never be combined.
Do they have the same side-effect profile? ▾
No — they belong to different classes and have distinct side-effect profiles. Each has its own prescribing information.
Products with Oseltamivir
Products with Acyclovir
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.