What Is Zovirax? Uses, Dosage, and What You Need to Know in 2026

Zovirax is the brand name for acyclovir, one of the most widely used antiviral medications in the world. It was first approved by the FDA in 1982 and has since become a cornerstone treatment for herpes simplex virus (HSV) and varicella-zoster virus (VZV) infections. Here's everything you need to know about it in 2026.

What Is Zovirax (Acyclovir)?

Zovirax (acyclovir) is a prescription antiviral medication classified as a synthetic purine nucleoside analogue. It does not kill herpes viruses outright, but it works by blocking the virus's ability to copy its own DNA — stopping or slowing the infection.

Acyclovir does not cure herpes infections. The virus remains dormant in nerve cells even after symptoms resolve. However, acyclovir reduces the severity and duration of outbreaks and, when taken daily (suppressive therapy), significantly reduces the frequency of recurrences and the risk of transmitting the virus to others.

What Conditions Does Zovirax Treat?

FDA-approved indications for oral acyclovir include:

Genital herpes (HSV-2 and HSV-1): Treatment of initial episodes, episodic treatment of recurrences, and chronic suppressive therapy (6+ episodes per year)

Herpes zoster (shingles): Acute treatment to reduce duration and severity of the rash and pain; most effective when started within 72 hours of rash onset

Varicella (chickenpox): Most effective in adults, adolescents, and children 2+ years; significantly shortens duration when started within 24 hours of rash onset

Herpes labialis (cold sores): Topical cream (5%) approved for adults and adolescents 12+ to treat recurrent cold sores on lips and face

Mucocutaneous HSV in immunocompromised patients: Topical ointment is approved for this indication

HSV encephalitis, neonatal herpes, severe VZV: Treated with IV acyclovir (sodium injection); these are life-threatening conditions requiring hospitalization

Available Forms and Strengths

Capsules: 200 mg

Tablets: 400 mg (white, shield-shaped) and 800 mg (light blue, oval)

Oral suspension: 200 mg per 5 mL (banana-flavored), useful for children or adults who can't swallow tablets

Topical cream: 5% (50 mg/g) in an aqueous cream base

Topical ointment: 5% (50 mg/g) in a polyethylene glycol base

IV injection: 50 mg/mL solution (acyclovir sodium); for hospital use only

Typical Dosing by Condition

Genital herpes, initial episode: 200 mg every 4 hours while awake (5 times daily) for 10 days; or 400 mg every 8 hours for 7–10 days

Suppressive therapy: 400 mg twice daily (every 12 hours) for up to 12 months, then re-evaluate

Herpes zoster (shingles): 800 mg five times daily for 7–10 days

Chickenpox: 20 mg/kg (up to 800 mg) four times daily for 5 days (children); 800 mg four times daily for 5 days (adults)

Cold sores (topical cream): Apply 5 times daily for 4 days, starting at first sign of symptoms

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How to Take Zovirax Safely

Take oral acyclovir with or without food — food does not significantly affect absorption

Take each dose with a full 8-ounce glass of water

Drink 6–8 glasses of water daily to protect kidneys from crystallization

Start treatment as early as possible at the first sign of symptoms for best results

For shingles: treatment started within 72 hours of rash onset is significantly more effective

Cost and Availability in 2026

Generic acyclovir is one of the most affordable antiviral medications available. With a GoodRx or SingleCare coupon, you can pay as little as $8–$15 for 60 tablets of acyclovir 400 mg. Insurance typically covers it at Tier 1 with a $0–$20 copay. For a full breakdown of costs and savings programs, see our guide to saving money on Zovirax.

If your pharmacy is out of stock, use medfinder to find which pharmacies near you have acyclovir in stock.