Acyclovir vs Valtrex: side-by-side comparison
Acyclovir (Acyclovir) and Valtrex (Valacyclovir) both belong to the Antiviral Medications class. They share clinical context but use different active ingredients. The choice between them depends on mechanism nuances, side-effect profile and individual response.
| Property | Acyclovir | Valtrex |
|---|---|---|
| Active ingredient | Acyclovir | Valacyclovir |
| Manufacturer | Various | GlaxoSmithKline |
| Class | Antiviral Medications | Antiviral Medications |
| Strengths | 200mg, 400mg, 800mg | 500mg, 1000mg |
| Forms | tablet, capsule, oral suspension, topical cream | tablet |
What's the same
Acyclovir and Valtrex both belong to the Antiviral Medications class and are used for partially overlapping indications. The active ingredients — Acyclovir vs Valacyclovir — share the same therapeutic approach, so many safety and management points carry across both.
Key differences
Meaningful differences are in active ingredient (Acyclovir vs Valacyclovir), strengths (200mg, 400mg, 800mg vs 500mg, 1000mg), forms (tablet, capsule, oral suspension, topical cream vs tablet), and the mechanism, half-life and side-effect nuances that distinguish members of the class.
Mechanism and action
Acyclovir: Acyclovir is a guanosine analogue selectively phosphorylated by viral thymidine kinase to its monophosphate form, then by cellular kinases to acyclovir triphosphate. Valtrex: Valacyclovir is rapidly and almost completely converted to acyclovir during first-pass intestinal and hepatic metabolism by valacyclovir hydrolase.
When Acyclovir is preferred
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 labialis, mucocutaneous herpes simplex in immunocompromised patien…
When Valtrex is preferred
Valtrex is approved in adults for the treatment of herpes simplex virus infections, including genital herpes (initial episodes, recurrent episodes and suppressive therapy), herpes labialis (single-day high-dose regimen), reduction of transmission in heterosexual immunocompetent a…
Frequently asked questions
Is Acyclovir or Valtrex better? ▾
There is no single answer. Acyclovir and Valtrex both belong to the Antiviral Medications class but differ in mechanism nuances, half-life and side-effect profile. Preference depends on the patient, the prescriber and prior response to other therapies.
Can I switch from Acyclovir to Valtrex? ▾
Switching within the Antiviral Medications class is done under supervision, typically using equivalent doses and a follow-up period to confirm response and tolerance. It is not a self-directed decision.
Do Acyclovir and Valtrex have the same side effects? ▾
They share many of the Antiviral Medications class side effects, with differences from mechanism and dose. Each medication's prescribing information lists specifics.
More Acyclovir comparisons
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.