• Aciclovir is used to treat viral infections.
  • Take your doses regularly and complete the full course prescribed, otherwise your infection may re-occur.
  • Drink plenty of fluids while you are taking aciclovir. It is important not to become dehydrated.

About aciclovir

Type of medicine Antiviral
Used for Viral infections
Also called Zovirax®
Available as Injection, tablet, dispersible tablet and oral liquid form

Aciclovir is used to treat viral infections such as genital herpes (a sexually transmitted infection), cold sores, shingles (sometimes called herpes zoster), and chickenpox. Shingles and chickenpox are caused by the varicella-zoster virus. It is also useful in preventing genital herpes and in preventing viral infections occurring in those with a lowered immune system.

Aciclovir works by preventing the herpes viruses from multiplying. This stops the growth of the virus.

Before taking aciclovir

Before taking aciclovir make sure your doctor or pharmacist knows:

  • If you are pregnant, trying for a baby or breast-feeding.
  • If you have kidney problems.
  • If you are over 65 years of age.
  • If you are taking other medicines, including those available to buy without a prescription, herbal or complementary medicines.
  • If you have ever had an allergic reaction to this or to any other medicine.

How to take aciclovir

  • Before beginning treatment, read the manufacturer's printed information leaflet.
  • Take aciclovir exactly as directed by your doctor. It can be taken before or after food.
  • Try to take aciclovir at the same times each day to avoid missing any doses. Spread your doses out evenly during the day.
  • If you have been prescribed the dispersible tablet form of aciclovir they should be dissolved in a glass of water.
  • You must complete the course of aciclovir, otherwise your infection may return.
  • If you forget to take a dose, take it as soon as you remember unless it is nearly time for your next dose, in which case leave out the missed dose. Do not take two doses together to make up for a missed dose.

Getting the most from your treatment

  • You must drink plenty while taking aciclovir. Do not let yourself become dehydrated.
  • Aciclovir may cause your skin to become more sensitive to sunlight than it is usually. Try to avoid sunlight or use a suncream with a sun protection factor (SPF) of 15 or higher until you know how your skin reacts. Do not use sunbeds.
  • If you have been prescribed aciclovir for genital herpes, it is recommended that you wear a condom during sexual contact to prevent spreading the infection, even if treatment with aciclovir has begun. You should not have sex however, if you have sores or blisters.
  • If you are having any treatment like an operation or dental treatment, tell the person carrying out the treatment that you are taking aciclovir.
  • If you buy any medicines, check with a pharmacist that they are safe to take with aciclovir.

Can aciclovir cause problems?

Along with their useful effects, all medicines can cause unwanted side-effects although not everyone experiences them. These usually improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.

Possible aciclovir side-effects What can I do if I experience this?
Feeling or being sick, stomach ache Eat little and often. Stick to simple foods
Itching and/or rash If this becomes a problem, speak with your doctor
Headache Ask your pharmacist to recommend a suitable painkiller. If the headache continues speak with your doctor
Diarrhoea Drink plenty of water to replace any lost fluids
Tiredness Make sure your reactions are normal before driving, operating machinery or doing any other jobs which could be dangerous if you were not fully alert

If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist.

How to store aciclovir

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.