Cymex Ultra


  • 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.
  • This cream is for you. Do not share it with others even if their symptoms are the same as yours.

About aciclovir cream

Type of medicine Antiviral cream
Used for Treatment of cold sores or genital herpes
Also called Cymex Ultra®; Virasorb®; Zovirax®
Available as Cream

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 they may not last as long as usual and may be less severe. Aciclovir cream is available on prescription, and you can also buy it without a prescription at a pharmacy 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 and Aciclovir eye ointment for more information about these other uses of aciclovir.

Before using aciclovir cream

To make sure 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 given on the advice of a doctor.
  • If your immune system is not working properly (for instance, if you have AIDS).
  • 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.

How to apply aciclovir cream

  • Before you start this treatment, read the manufacturer's printed information leaflet from inside your pack. The leaflet will give you more information about the specific brand of cream you have been given, and a full list of side-effects which you may 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. Dab the cream on 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 4-5 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 at your usual times.

Getting the most from your treatment

  • 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.

Can aciclovir cream cause problems?

Along with their useful effects, most 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.

Aciclovir side-effects - these are uncommon and affect less than 1 in 100 people who use this cream What can I do if I experience this?
Mild stinging, burning, redness, itchy or dry skin These 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 aciclovir, speak with your doctor or pharmacist.

How to store aciclovir cream

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