You can take aciclovir either with or without food.
Space out your doses evenly over the day, and complete the full course of treatment.
Drink plenty of water. It is important that you don't become lacking in fluid in the body (dehydrated).
|Type of medicine||An antiviral medicine|
|Used for||Viral infections in adults and children|
|Also called||Acyclovir (in US); Zovirax®|
|Available as||Tablets, dispersible tablets and oral liquid medicine|
Aciclovir is used to treat two common viral infections - varicella-zoster and herpes simplex. The varicella-zoster virus is the cause of chickenpox and shingles. Herpes simplex viruses cause cold sores and genital herpes. Aciclovir works by preventing viruses from multiplying, and this reduces the severity of the infection and stops it from spreading. As well as treating infections, aciclovir can also be prescribed to prevent some viral infections from occurring. This is particularly the case in people who have a lowered immune system.
Although some herpes infections (for example, cold sores) can be treated with creams or ointments, more severe infections need to be treated with tablets or medicine taken by mouth. This leaflet provides information on how to take aciclovir tablets and medicine. Information about the topical forms of aciclovir (creams and ointments) is not included in this leaflet. See the separate medicine leaflets called Aciclovir cream and Aciclovir eye ointment for more information about how to use these preparations.
Before taking aciclovir
Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking aciclovir it is important that the person prescribing it for you knows:
- If you are pregnant or breastfeeding (although aciclovir is not known to be harmful to a baby).
- If you have any problems with the way your kidneys work.
- If you are taking or using any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.
- If you have ever had an allergic reaction to a medicine.
How to take aciclovir
- Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about aciclovir, and it will also provide you with a full list of the side-effects which you could experience from taking it.
- Your dose will depend upon the type of infection you have, so take aciclovir exactly as your doctor tells you to. Typically, doses range from 200 mg to 800 mg, and these doses are taken either three, four or five times daily. Your doctor or pharmacist will tell you what dose is right for you, and this information will also be printed on the label of the pack to remind you about what was said to you.
- Space out your doses evenly during the day. You can take aciclovir either with or without food.
- Even if you feel your infection has cleared up, keep taking aciclovir until the course is finished (unless your doctor tells you to stop sooner). This is to prevent the infection from coming back. The course of treatment prescribed could last between 2-10 days. If you still feel unwell after finishing the course, go back to see your doctor.
- If you have been prescribed a dispersible tablet - these can be stirred into a small glassful (50 ml) of water to make them easier to swallow. You can, however, swallow them as normal if you prefer.
- If you forget to take a dose, take it as soon as you remember and then continue as before. Try to take the correct number of doses each day, but do not take two doses at the same time to make up for a missed dose.
Getting the most from your treatment
- You should drink plenty while you are on aciclovir to keep your kidneys working well. Drinking water is best, but hot drinks and non-alcoholic cold drinks are also suitable.
- Aciclovir could cause your skin to become more sensitive to sunlight than it is usually. Avoid strong sunlight and sunbeds, and use a sun cream with a high sun protection factor until you know how your skin reacts.
- If you have been prescribed aciclovir for genital herpes, do not have sex while you have sores or blisters. Even after these have healed, there is still a small chance that you may pass on the virus when you have sex - using a condom reduces this risk.
- If you are having an operation or any other medical treatment, tell the person carrying out the treatment that you are taking aciclovir.
Can aciclovir cause problems?
Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the more common ones associated with aciclovir. The best place to find a full list of the side-effects which can be associated with your medicine, is from the manufacturer's printed information leaflet supplied with the medicine. Alternatively, you can find an example of a manufacturer's information leaflet in the reference section below. Speak with your doctor or pharmacist if any of the following continue or become troublesome.
|Common aciclovir side-effects (these affect less than 1 in 10 people)||What can I do if I experience this?|
|Feeling sick (nausea) or being sick (vomiting), stomach ache||Stick to simple foods - avoid fatty or spicy meals|
|Itchy rash, feeling hot||If either is troublesome, speak with your doctor|
|Headache||Drink plenty of water and ask your pharmacist to recommend a suitable painkiller. If the headaches continue, speak with your doctor|
|Diarrhoea||Drink plenty of water to replace any lost fluids|
|Feeling dizzy or tired||Do not drive and do not use tools or machines while affected|
If you experience any other symptoms which you think may be due to the medicine, speak with your doctor or pharmacist for further advice.
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.
Important information about all medicines
Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.
This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
If you buy any medicines, check with a pharmacist that they are suitable to take with your other medicines.
Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
If you have any questions about this medicine ask your pharmacist.
Further reading and references
Manufacturer's PIL, Zovirax® Tablets 200 mg; GlaxoSmithKline UK, The electronic Medicines Compendium. Dated December 2017.
Manufacturer's PIL, Zovirax® Tablets 800 mg; GlaxoSmithKline UK, The electronic Medicines Compendium. Dated December 2017.
British National Formulary, 78th Edition (Sep 2019); British Medical Association and Royal Pharmaceutical Society of Great Britain, London.