Acyclovir (aciclovir)

Antiviral
PRESCRIPTION ONLY IN INDIA

Acyclovir is a antiviral found in 2 medicines sold in India, such as Acivir 400, Zovirax 400. Below: what it is for, how it works, how to take it, side effects, interactions and pregnancy advice.

Also called: aciclovir

What it is used for

Treats cold sores, genital herpes, chickenpox and shingles.

How it works

An antiviral that stops herpes viruses copying; used for cold sores, genital herpes, chickenpox and shingles.

How to take it

Tablets: usually 200 to 800 mg up to five times a day for 5 to 7 days, started as early as possible. Cream: 5 times a day at the first tingle. Drink plenty of water.

Common side effects

  • Nausea
  • Headache
  • Diarrhoea
  • Stinging with cream

Get medical help straight away if

  • Confusion or much less urine (kidneys, mainly with high doses)
  • Severe rash

Be careful

Start early for best effect; drink plenty of water.

Other medicines and interactions

Kidney risk with other kidney-affecting medicines; dose reduced in kidney disease.

Pregnancy and breastfeeding

Considered safe in pregnancy and breastfeeding when needed.

Brands of Acyclovir (2)

Acivir 400Zovirax 400

Common questions

What is Acyclovir used for?

Treats cold sores, genital herpes, chickenpox and shingles.

How does Acyclovir work?

An antiviral that stops herpes viruses copying; used for cold sores, genital herpes, chickenpox and shingles.

How should I take Acyclovir?

Tablets: usually 200 to 800 mg up to five times a day for 5 to 7 days, started as early as possible. Cream: 5 times a day at the first tingle. Drink plenty of water.

What are the side effects of Acyclovir?

Common: Nausea, headache, diarrhoea, stinging with cream. Get help straight away for: Confusion or much less urine (kidneys, mainly with high doses), severe rash.

Does Acyclovir interact with other medicines?

Kidney risk with other kidney-affecting medicines; dose reduced in kidney disease.

Is Acyclovir safe in pregnancy and breastfeeding?

Considered safe in pregnancy and breastfeeding when needed.

Does Acyclovir need a prescription in India?

Yes. In India it is a prescription (Schedule H) medicine, so a pharmacist should sell it only with a doctor's prescription.

Which brands contain Acyclovir?

Acivir 400, Zovirax 400.

Sources and further reading

NHS (UK National Health Service) and MedlinePlus (US National Library of Medicine) are free, reviewed medicine guides. Brand names and doses there may differ from India.

Last reviewed 31 October 2026. Written by Satya Babu from standard prescribing information.

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For information only, not medical advice. This page is a plain-language summary written from standard prescribing information and the public guides linked below. Brands sometimes change their formula, so always check the composition printed on the pack. Doses here are typical adult doses; yours may differ. Do not start, stop or change a medicine without your doctor or pharmacist, and keep all medicines away from children. In an emergency, call 112 (India) or your local emergency number.