Antiviral Medication for Genital Herpes

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Genital herpes is an infection of the genitals (penis in men, vulva and vagina in women) and surrounding area of skin. It is caused by the herpes simplex virus. Antiviral medicines such as aciclovir, famciclovir, and valaciclovir are used to treat genital herpes infection. They do not clear the virus completely from the body, so the symptoms may come back (recur). They work by stopping the virus from multiplying, which reduces the duration and severity of symptoms.

Genital herpes is an infection of the genitals (penis in men, vulva and vagina in women) and surrounding area of skin. The buttocks and anus may also be affected. It is caused by the herpes simplex virus.

Genital herpes is usually a sexually transmitted infection. Many people who are infected with this virus never have symptoms but can still pass on the infection to others. If symptoms occur, they can range from a mild soreness to painful blisters on the genitals and surrounding area.

This leaflet just discusses antiviral medication for genital herpes. See separate leaflet called Genital Herpes for more general details on genital herpes infection.

There are three antiviral medicines that are currently usually used to treat genital herpes:

They all come in different brand names. They work by stopping the herpes virus from multiplying. They do not clear the virus from the body. If an antiviral medicine is started early in an episode of symptoms, it tends to reduce the severity and duration of symptoms during an episode of genital herpes.

It is thought that these medicines all work as well as each other when used to treat genital herpes.

An antiviral medicine is commonly prescribed for a first episode of genital herpes. (A first episode of genital herpes is also called a primary episode.) A five-day course of treatment is usual but this may be extended by a few days if blisters are still forming. With a first episode of genital herpes, the sores and blisters may last from about 10 days up to 28 days. This is usually much reduced if you start an antiviral medicine within five days of the onset of symptoms. The earlier the medicine is started, the better chance of easing symptoms.

Further episodes of symptoms (recurrences) tend to be milder and usually last just a few days. You usually have 7-10 days of symptoms rather than 10-28 days that can occur with a first episode. Antiviral medication is often not needed for recurrences. Painkillers, salt baths, and local anaesthetic ointment (such as lidocaine) for a few days may be sufficient to ease symptoms. However, an antiviral medicine may be advised for recurrent episodes of genital herpes in the following situations:

  • If you have severe recurrences. If you take a course of an antiviral medicine as soon as symptoms start, it may reduce the duration and severity of symptoms. You may be prescribed a supply of medication to have ready at home to start as soon as symptoms begin. This kind of "as needed" treatment tends to be prescribed if you are getting severe attacks of genital herpes fewer than six times a year. There are a number of different options of courses of treatment to take, ranging from one to six days in length, and with different daily regimes.
  • If you have frequent recurrences. You may be advised to take an antiviral medicine every day. In most people who take medication every day, the recurrences are either stopped completely, or their frequency and severity are greatly reduced. A lower maintenance dose rather than the full treatment dose is usually prescribed. A typical plan is to take a 6- to 12-month course of treatment. You can then stop the medication to see if recurrences have become less frequent. This type of continuous treatment can be repeated if necessary. This type of daily treatment tends to be prescribed if you have severe attacks of genital herpes more than six times per year.
  • For special events. A course of medication may help to prevent a recurrence during special times. This may be an option even if you do not have frequent recurrences but want to have the least risk of a recurrence - for example, during a holiday or during exams.

A specialist will normally advise about what to do if you develop genital herpes whilst you are pregnant, or if you have recurrent genital herpes and become pregnant. This is because there may be a chance of passing on the infection to your baby.

A first episode of genital herpes whilst you are pregnant

If you develop a first episode of genital herpes within the final six weeks of your pregnancy, or around the time of the birth, the risk of passing on the virus to your baby is highest. In this situation there is about a 4 in 10 chance of the baby developing a herpes infection. The baby may develop a very serious herpes infection if he or she is born by a vaginal delivery.

Therefore, in this situation your specialist is likely to recommend that you have a caesarean section delivery. This will greatly reduce the chance of the baby coming into contact with the virus (mainly in the blisters and sores around your genitals). Infection of the baby is then usually (but not always) prevented.

However, if you decide against a caesarean section and decide to opt for a vaginal birth, the specialist is likely to recommend that you be given antiviral medication (usually aciclovir). This is given into your veins (intravenously) during your labour and birth. They may also suggest that antiviral medication be given to your baby after he or she is born.

As long as there are two months between your catching the virus and giving birth to your baby, a normal vaginal delivery is likely to be safe for the baby. This is because there will be time for your body to produce protective proteins called antibodies. These will be passed on to the baby through your bloodstream to protect it when it is being born. The specialist may advise that you should be treated with antiviral medication at the time of infection. This helps the sores to clear quickly. In addition, your doctor may advise that you should take antiviral medication in the last four weeks of pregnancy to help prevent a recurrence of herpes at the time of childbirth. Antiviral medicines such as aciclovir have not been found to be harmful to the baby when taken during pregnancy.

If you have recurrent genital herpes and become pregnant

If you have recurring episodes of genital herpes, the risk to your baby is low. Even if you have an episode of blisters or sores during childbirth, the risk of your baby developing a serious herpes infection is low. This is because you pass on some antibodies and immunity to the baby during the final two months of pregnancy.

For most women with recurrent genital herpes, it is felt to be safe to have a normal vaginal delivery. This is even the case if you have a recurrence whilst giving birth. However, you and your specialist will weigh up the pros and cons of vaginal delivery vs caesarean section. If you do have a recurrent episode when you go into labour, you should discuss your options with your specialist and together decide the best way that your baby should be delivered.

Often antiviral medication will be advised in the last four weeks running up to childbirth. This may help to prevent a recurrence of blisters during childbirth. Again, your specialist will be able to advise on the pros and cons.

In summary

A first episode of herpes around the time of birth can be serious for the baby and a caesarean section is usually advised. In any other situation - an earlier primary infection or a history of recurrent episodes - the risk to the baby is low and your specialist will advise on possible options. This may include taking antiviral medication, as well as the type of delivery method.

Most people who take antiviral medication get no side-effects, or only minor ones. Feeling sick (nausea), being sick (vomiting), diarrhoea, and tummy (abdominal) pain, as well as skin rashes (including photosensitivity and itching) are the most common side-effects.

Read the leaflet inside the medication packet for a full list of possible side-effects.

If you think you have had a side-effect to one of your medicines you can report this on the Yellow Card Scheme. You can do this online at the following web address:

The Yellow Card Scheme is used to make pharmacists, doctors and nurses aware of any new side-effects that medicines or any other healthcare products may have caused. If you wish to report a side-effect, you will need to provide basic information about:

  • The side-effect.
  • The name of the medicine which you think caused it.
  • The person who had the side-effect.
  • Your contact details as the reporter of the side-effect.

It is helpful if you have your medication - and/or the leaflet that came with it - with you while you fill out the report.

Further help & information

Original Author:
Dr Tim Kenny
Current Version:
Peer Reviewer:
Dr Helen Huins
Document ID:
4458 (v43)
Last Checked:
Next Review:
The Information Standard - certified member
Now read about Genital Herpes Simplex

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