Acyclovir Is a Prescription Antiviral Medication Used to Treat Herpes Virus Infections Including Genital Herpes, Shingles, and Chickenpox

If your doctor just prescribed Acyclovir — or you're researching it before an appointment — this guide covers everything you need to know in plain language. We'll explain what it is, what it treats, how to take it, and what it costs in 2026.

What Is Acyclovir?

Acyclovir is a generic prescription antiviral medication. It belongs to a class of drugs called nucleoside analog antivirals, which work by stopping viruses from replicating. Acyclovir specifically targets herpes viruses — it doesn't work against other types of viruses like the flu or COVID-19.

The original brand name is Zovirax, manufactured by GlaxoSmithKline (GSK). Today, Acyclovir is available from multiple generic manufacturers, making it widely accessible and affordable. Other brand-name products containing Acyclovir include Sitavig (a buccal tablet for cold sores) and Xerese (a combination cream with Hydrocortisone).

Acyclovir is not a controlled substance — it has no potential for abuse and does not require DEA scheduling. It does require a prescription from a licensed healthcare provider. Learn more about how to find a doctor who can prescribe Acyclovir.

The FDA first approved Acyclovir in 1982, and it has been used safely for over 40 years. For a detailed explanation of how it works in your body, see our guide on how Acyclovir works.

What Is Acyclovir Used For?

Acyclovir is FDA-approved to treat several conditions caused by herpes viruses:

FDA-Approved Uses

• Genital herpes (HSV-2 and HSV-1) — Treatment of initial outbreaks, treatment of recurrent episodes, and long-term suppressive therapy to reduce outbreak frequency
• Herpes zoster (shingles) — Treatment of the painful, blistering rash caused by reactivation of the varicella-zoster virus, especially in older adults
• Varicella (chickenpox) — Treatment in children aged 2 years and older and in adults, particularly immunocompromised patients
• Herpes labialis (cold sores) — The Sitavig buccal tablet is specifically approved for cold sores; topical Acyclovir cream is also used
• Herpes simplex encephalitis — The IV form is the first-line treatment for this serious brain infection
• Mucocutaneous HSV in immunocompromised patients — Both treatment and prevention of herpes infections in patients with weakened immune systems

Off-Label Uses

Doctors sometimes prescribe Acyclovir for conditions not listed on the FDA label, including:

• Herpes simplex keratitis (eye infections)
• Eczema herpeticum
• HSV/VZV prophylaxis in transplant recipients and chemotherapy patients
• Bell's palsy (as an adjunct with corticosteroids)
• Oral hairy leukoplakia

How Is Acyclovir Taken?

Acyclovir comes in several forms:

• Oral capsules — 200 mg
• Oral tablets — 400 mg and 800 mg
• Oral suspension (liquid) — 200 mg per 5 mL
• Topical cream — 5%
• Topical ointment — 5%
• Buccal tablet — 50 mg (Sitavig, applied to the gum)
• Intravenous injection — 50 mg/mL (hospital use)

Typical Dosing by Condition

Dosing depends on what you're being treated for:

• Genital herpes (initial outbreak): 200 mg five times daily OR 400 mg three times daily for 7-10 days
• Genital herpes (recurrent episode): 200 mg five times daily OR 400 mg three times daily for 5 days
• Genital herpes (daily suppressive therapy): 400 mg twice daily, ongoing
• Herpes zoster (shingles): 800 mg five times daily for 7-10 days
• Chickenpox: 20 mg/kg (up to 800 mg max) four times daily for 5 days
• HSV encephalitis (IV): 10 mg/kg every 8 hours for 14-21 days

How to Take Acyclovir Properly

• Take with or without food — though food can help if you experience nausea
• Drink plenty of water to stay hydrated and protect your kidneys
• Swallow capsules and tablets whole
• Shake the oral suspension well before each dose
• Space doses evenly throughout the day
• Start treatment as soon as symptoms appear for best results
• Complete the full course even if you feel better

Who Should Not Take Acyclovir?

Acyclovir is safe for most people, but there are some important exceptions:

Contraindications

• Known hypersensitivity (allergy) to Acyclovir or Valacyclovir
• History of severe allergic skin reaction to Acyclovir or Valacyclovir

Use with Caution

• Kidney disease: Dose adjustment is required based on creatinine clearance. Acyclovir is cleared by the kidneys, and impaired function increases the risk of toxicity.
• Elderly patients: Higher risk of kidney and neurological side effects; dose adjustment is often needed
• Dehydration: Increases risk of kidney damage — always stay well-hydrated
• Concurrent nephrotoxic medications: Using Acyclovir with drugs like Aminoglycosides, Amphotericin B, Foscarnet, or Tenofovir increases kidney risk

For a full list of medication interactions, see our guide on Acyclovir drug interactions.

Pregnancy and Breastfeeding

Acyclovir is FDA Pregnancy Category B — generally considered safe when the benefits outweigh the risks. It is commonly prescribed during pregnancy to prevent genital herpes outbreaks near delivery. Acyclovir is excreted in breast milk; use with caution while breastfeeding and discuss with your doctor.

For detailed side effect information, read our article on Acyclovir side effects.

How Much Does Acyclovir Cost?

One of Acyclovir's biggest advantages is affordability. As a widely available generic, it's one of the least expensive antiviral medications on the market:

• With a discount card (SingleCare, GoodRx): As low as $8-$15 for 30 tablets of 400 mg
• Average retail cash price (no coupon): $70-$105 for 60 tablets of 400 mg
• Brand-name Zovirax cream: $400+ (generic cream is much cheaper)
• Insurance: Covered by most plans as a preferred Tier 1 generic — typically low or $0 copay

No prior authorization is usually required for oral generic Acyclovir. Brand products like Sitavig or Zovirax may require step therapy (trying the generic first).

For a complete guide to savings options, read how to save money on Acyclovir.

Final Thoughts

Acyclovir is a proven, affordable, and widely available antiviral that has been helping patients manage herpes virus infections for over 40 years. Whether you're treating a first genital herpes outbreak, managing shingles, or on long-term suppressive therapy, it's one of the most well-studied medications in its class.

If you've been prescribed Acyclovir and need help finding it at a pharmacy near you, Medfinder can show you which pharmacies currently have it in stock. And if you're a healthcare provider, check out our provider's guide to helping patients save on Acyclovir.