Zovirax (Acyclovir) vs. Popular Antiviral Alternatives: Which Is Right for You?

Oct, 5 2025

Key Takeaways

• Zovirax is a brand‑name formulation of acyclovir with well‑documented efficacy for cold sores, genital herpes and shingles.
• Valacyclovir and famciclovir offer once‑ or twice‑daily dosing, which many patients find more convenient.
• Topical penciclovir works only for superficial lesions and is less useful for systemic infections.
• Cost varies widely in the UK; generic acyclovir is cheapest, while brand products can be up to three times higher.
• Side‑effect profiles are similar, but renal impairment requires dose adjustment for all oral antivirals.

What Is Zovirax?

When treating herpes infections, Zovirax is a brand‑name oral and topical formulation of the antiviral drug acyclovir, approved for cold sores, genital herpes and shingles. It works by mimicking the building blocks of viral DNA, inserting itself into the viral replication chain and halting virus multiplication. The standard oral dose is 200mg five times a day for five days (cold sores) or 400mg three times a day for ten days (genital herpes). A 5% cream version is applied five times daily for four days.

How Antiviral Medications Work

All the drugs we’ll compare belong to the nucleoside analog class. They are converted inside infected cells into a phosphorylated form that blocks the viral DNA polymerase. The key differences lie in how quickly they are activated, how long they stay in the bloodstream, and the convenience of the dosing schedule.

Major Alternative Antivirals

Valacyclovir is the pro‑drug of acyclovir that converts to acyclovir in the body, allowing higher plasma levels with fewer tablets. It is sold under the brand name Valtrex and is typically taken twice daily for genital herpes or once daily for shingles.

Famciclovir is a pro‑drug of penciclovir, offering a longer half‑life than acyclovir and permitting twice‑daily dosing for most indications. The common brand Famvir is prescribed for shingles and genital herpes.

Penciclovir is a topical antiviral cream (Denavir) that penetrates skin lesions but does not treat systemic infections. It is applied five times a day for ten days to cold‑sore lesions.

Generic Acyclovir is the off‑label, low‑cost version of the same active ingredient found in Zovirax, available in tablets and cream. Dosing mirrors Zovirax, but price is substantially lower.

Docosanol is an over‑the‑counter skin‑protective agent (Abreva) that blocks viral entry rather than replication. It is used only for early‑stage cold sores and has a different mechanism than the nucleoside analogs.

Comparison Table

How to Choose the Right Antiviral

Deciding which drug fits your situation comes down to three practical questions:

1. What infection are you treating? Systemic illnesses like shingles or genital herpes need oral medication (Zovirax, Valacyclovir, Famciclovir). Surface‑only outbreaks such as first‑time cold sores can be managed with topical penciclovir or docosanol.
2. How many pills can you realistically take? If you struggle with five‑times‑daily regimens, Valacyclovir’s twice‑daily schedule often wins. For short‑term cold‑sores, the 5‑day 5‑times‑daily course of Zovirax may be acceptable.
3. What is your budget? In the UK, generic acyclovir provides the same antiviral action for a fraction of the cost. If you have prescription coverage that favours one brand, factor that in.

Another hidden factor is kidney function. All oral antivirals are cleared renally, so patients with reduced eGFR need dose adjustments. Your GP or pharmacist will calculate the right dose based on creatinine clearance.

Practical Tips & Cost‑Saving Strategies

• Ask your pharmacist about generic substitution. In most cases, generic acyclovir is interchangeable with Zovirax without loss of efficacy.
• Check the NHS prescription exemption list. Some antivirals are free for certain chronic conditions.
• If you need the medication repeatedly, request a repeat prescription to avoid multiple GP visits.
• Consider buying a 28‑day supply of Valacyclovir if you have frequent outbreaks; bulk pricing often reduces the per‑day cost.
• For OTC options (docosanol), start treatment within 24hours of lesion appearance for best results.