Skip to content

Aciclovir cream (Cymex Ultra, Virasorb, Zovirax)

joe91193 ashley44394 kiki4747 1191 Users are discussing this topic

Use aciclovir cream five times a day for at least five days.

To avoid spreading the infection, wash your hands before and after applying aciclovir. Remember infection can also spread to others.

Do not share the same tube of cream with other people.

Type of medicineAn antiviral cream
Used forTreatment of cold sores and genital herpes
Also calledCymex Ultra®; Virasorb®; Zovirax®
Available asCream

Aciclovir is an antiviral agent. It works by attacking the herpes simplex virus, of which there are two types:

  • Type 1 herpes simplex virus is the usual cause of cold sores around the mouth. It also causes up to half of the cases of genital herpes.
  • Type 2 herpes simplex virus usually only causes genital herpes. It can sometimes cause cold sores.

Aciclovir does not kill the herpes simplex virus, but it does prevent it from multiplying. This means that, although it may have little effect on existing blisters, it can prevent them from getting worse. If you use aciclovir cream as soon as your symptoms start then it will reduce the severity and duration of the symptoms. Aciclovir cream is available on prescription for the treatment of cold sores and genital herpes infections. You can also buy some brands without a prescription in order to treat cold sores.

There are other preparations of aciclovir available which are not dealt with by this medicine leaflet. See the separate leaflets called Aciclovir for viral infections and Aciclovir eye ointment for more information about other formulations of aciclovir.

To make sure that this is the right treatment for you, before you start using aciclovir cream it is important that your doctor or pharmacist knows:

  • If you are pregnant. This is because, if you are expecting a baby, medicines should only be used on the advice of a doctor.
  • If your immune system is not working as well as it should (for instance, if you have HIV or AIDS). This is because you may need additional antiviral treatment.
  • If you are taking or using any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • If you have ever had an allergic reaction to a medicine or skin product.
  • Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about using aciclovir cream and will provide you with a full list of the side-effects which you could experience from using it.
  • Apply the cream five times a day. The best way to do this is to use it every four hours during the day (suggested times are 7 am, 11 am, 3 pm, 7 pm amd 11 pm). Dab the cream on to the area rather than rubbing it in. This will minimise any damage to the blisters, which could cause pain and spread the virus around.
  • Start using the cream at the first sign of infection (for instance, when you first feel your skin tingling) and continue to use it for five days. This is often sufficient time for the sore to heal but you can continue to use the cream for a further five days if needed. Remember to wash and dry your hands before and after using aciclovir, to prevent spreading any infection.
  • If you forget to use the cream, apply it as soon as you remember and then continue using it again at your usual times.
  • Try to keep the areas affected by blisters as clean and dry as possible and only touch the sores when you apply the cream.
  • Aciclovir cream is not intended for use in your mouth or vagina, or near your eyes. This is because it may irritate these parts of your body. If you have sores in any of these areas, you should make an appointment to see your doctor, as alternative preparations can be prescribed which will be suitable for you to use.
  • When you have a cold sore you should not kiss anyone or allow anyone to come into skin contact with the sore. In particular, avoid kissing newborn babies and anyone who has a poor immune system. When you have no symptoms, you are not usually infectious.
  • Genital herpes simplex virus is very contagious when blisters are present. You should not have sex from the time your symptoms first start until they are fully over, as there is a high chance of passing on the virus.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the ones associated with creams containing aciclovir. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.

Aciclovir cream side-effects (these affect less than 1 in 10 people)What can I do if I experience this?
Flaking, itchy or dry skin, burning or stinging when applying the creamThese effects do not usually last for long but if any become troublesome speak with your doctor or pharmacist

If you experience any other symptoms which you think may be due to the cream, please speak with your doctor or pharmacist for further advice.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.
  • Check the label to see how long the cream can be kept once the pack has been opened.

This preparation is for use on the skin only. If you suspect that someone has swallowed some of it by accident, contact the accident and emergency department of your local hospital for advice.

If you are having an operation or dental treatment, tell the person carrying out the treatment which medicines you are using.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

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 & references

  • Manufacturer's PIL, Zovirax® Cream; GlaxoSmithKline UK, The electronic Medicines Compendium. Dated September 2013.
  • British National Formulary; 69th Edition (Mar 2015) British Medical Association and Royal Pharmaceutical Society of Great Britain, London

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Helen Allen
Current Version:
Peer Reviewer:
Dr John Cox
Document ID:
3252 (v24)
Last Checked:
Next Review:
The Information Standard - certified member
Patient Access app - find out more Patient facebook page - Like our page

People talking about Aciclovir cream (Cymex Ultra, Virasorb, Zovirax)