Acyclovir vs Azithromycin: side-by-side comparison
Acyclovir (Nucleoside antiviral) and Azithromycin (Macrolide antibiotic) 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 | Acyclovir | Azithromycin |
|---|---|---|
| Therapeutic class | Nucleoside antiviral | Macrolide antibiotic |
| CAS | 59277-89-3 | 83905-01-5 |
| ATC | J05AB01 | J01FA10 |
| Molecular weight | 225.21 g/mol | 748.98 g/mol |
| Brands with this active ingredient | 1 | 1 |
What they share
Acyclovir and Azithromycin 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
Acyclovir acts by a different mechanism than Azithromycin, 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
Acyclovir: Acyclovir is a guanosine analogue selectively phosphorylated by viral thymidine kinase to its monophosphate form, then by cellular kinases to acyclovir triphosphate. Azithromycin: Azithromycin reversibly binds the 50S ribosomal subunit of susceptible bacteria, inhibiting protein synthesis.
Indications compared
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… Azithromycin: Azithromycin is approved in adults and children for the treatment of respiratory tract infections, otitis media, skin and soft tissue infections, and sexually transmitted infections caused by susceptible organisms, inclu…
Safety profile
Acyclovir: Common adverse effects include nausea, headache, dizziness and skin rash. Azithromycin: Common adverse effects are gastrointestinal: nausea, diarrhoea and abdominal discomfort.
Frequently asked questions
Is Acyclovir better than Azithromycin? ▾
Acyclovir and Azithromycin are not "better or worse" — they treat different things. The sensible question is which fits your specific need.
Can Acyclovir and Azithromycin 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 Acyclovir
Products with Azithromycin
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.