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Question from practice: Herpes: when is it safe to have sex?

A. Genital herpes is caused by the herpes simplex virus, which can either be type I (commonly associated with cold sores) or type II (known as the genital strain). In the UK currently, genital lesions are equally likely to be caused by either type.

It appears that many infections are subclinical when the virus is first acquired and approximately 80 per cent of seropositive people are unaware that they have the infection. Initial infection may be either primary (ie, in someone who does not have pre-existing antibodies to either type I or II strains) or non-primary (where the individual has antibodies to the type other than that which they are being infected with). Already having one of the two types modifies the disease course, generally making it less severe.

Where patients have symptoms, these include:

  • Painful lesions on or around the genital area, which tend to erupt in crops
  • Painful or difficult urination (dysuria)
  • Vaginal or urethral discharge

The genital soreness can sometimes prevent individuals from walking normally, and patients can experience urinary retention. Patients can also have systemic symptoms, such as fever, malaise and myalgia, particularly in an initial attack. Meningitis can develop in extreme cases.


Diagnosis is clinical. The classic picture is blisters that develop into small shallow painful ulcers, sometimes accompanied by swollen lymph glands (lymphadenopathy) in the groin. Occasionally syphilis can mimic this picture and it is vital to exclude this with blood tests. Other causes of genital blistering and ulceration include Behçet’s syndrome, a rare autoimmune disorder.

If the blisters or ulcers are wet, a swab can be taken to confirm the diagnosis. Although results can take time, treatment should not be delayed.

Serology can have some use in forensic diagnosis (eg, to identify the perpetrator of a sexual assault) or in pregnancy (to identify women who are having a primary attack; see later) but is generally of little importance in most cases because many people in the UK have been in contact with herpes simplex in one way or another. It can differentiate between type I and II infection.


The initial attack normally lasts for 10 to 14 days. After this episode, the virus lies dormant in the local sensory ganglia but periodically activates with or without symptoms — a condition known as asymptomatic shedding. Recurrent attacks are often milder than the inital episode.

Factors that are commonly implicated in triggering recurrences include hormonal changes and stress, but these have not been scientifically proven. There is, however, an increased risk of recurrence if a patient is immunocompromised. In addition, people with HIV are more likely to shed the virus asymptomatically than those who do not have HIV. The presence of herpetic sores also increases the transmission of HIV.


  • Symptoms of genital herpes can be painful but about 80 per cent of seropositive people are unaware that they are infected.
  • An initial symptomatic attack may be treated with antivirals, saline baths, analgesia and topical anaesthetics.
  • Suppressive treatment with an antiviral is prescribed for those who have more than six recurrences a year or who have severe and distressing symptoms.
  • Sex should be avoided when lesions are present but the virus can also shed when there are no symptoms. Condoms can be used to help prevent transmission but they do not always cover the affected area.


The cost of treatment varies from around £4 for a course of aciclovir to over £100 for famciclovir, so some prescribers will have formulary restrictions.

Options for treating an initial attack are a five-day course of:

  • Aciclovir 200mg five times daily
  • Aciclovir 400mg tds
  • Valaciclovir 500mg bd
  • Famciclovir 250mg tds

All these regimens reduce the length and severity of the episode but do not affect the risk of recurrence or asymptomatic shedding. They should be started within five days of the onset of symptoms or when new lesions are still forming.

If the patient returns after the course of treatment and has new lesions still forming, it may be necessary to continue the treatment for a further five days.

Saline baths (one teaspoon of salt per pint of water), analgesia (eg, paracetamol) and topical anaesthetics, such as lidocaine 5 per cent ointment (used with caution to avoid sensitisation), may help alleviate symptoms.

In severe cases, patients may need to be admitted to hospital. Some require suprapubic catheterisation.

Self management


Most recurrent episodes of genital herpes are minor and can be treated with saline baths, analgesia and reassurance.

Antivirals may not be necessary. However, they are more effective when taken early in an episode so may be prescribed in advance for patients who tend to experience bad symptoms. They have been shown to reduce the severity and duration of an attack. Regimens used for a recurrent episode include five days’ of:

  • Aciclovir 200mg five times daily
  • Aciclovir 400mg tds
  • Valaciclovir 500mg bd
  • Famciclovir 125mg tds

Shorter courses can also work, for example:

  • Aciclovir 800mg tds 2/7
  • Famciclovir 1g bd for 1/7
  • Valaciclovir 500mg bd 3/7

Suppressive treatment

Taking antiviral medicines long-term reduces the rate of recurrence during treatment. It can also reduce the rate of asymptomatic shedding and transmission of the virus. Suppressive treatment is prescribed for those who have more than six recurrences a year or who have severe and distressing symptoms. Regimens include:

  • Aciclovir 400mg bd
  • Aciclovir 200mg qds
  • Valaciclovir 500mg od
  • Famciclovir 250mg bd

It is normally recommended to continue suppressive treatment for a year, and then stop to see how frequent the recurrence rate is afterwards. It is common to have a rebound recurrence at the end of treatment. Suppressive treatment can be continued if recurrences continue to be a problem.


Genital herpes can cause complications in pregnancy and specialist advice is required. If a pregnant woman acquires genital herpes during the last trimester of pregnancy, or goes into labour with genital herpes sores and delivers vaginally, there is a risk of neonatal herpes, which has high mortality and morbidity. Women who acquire herpes for the first time in pregnancy are given suppressive therapy for the last six weeks of the pregnancy. Caesarean section may also be considered. If a woman who already has herpes has a recurrence as she goes into labour, caesarean section again may be considered. Aciclovir is not licensed in pregnancy but there is considerable evidence of its safety and it is used widely.


There is considerable stigma among the general public about herpes, and many people with the disease encounter a great deal of distress while learning to live with it. Reassurance and teaching can help, along with patient information websites (eg, and printed material, particularly on how to broach the subject with a partner.

Counselling should include how the disease progresses, how to reduce the risk of transmission, the relative protection of condoms and treatment possibilities, including suppressive therapies.

Sufferers need to know to avoid sex during an episode, and about the possible risk of transmission through asymptomatic shedding. They should also be aware of the complications in pregnancy.

A number of people have herpes without symptoms and this fact is particularly important when symptoms present some time into a monogamous relationship and worries about fidelity come to the fore. Partner notification is important and can clarify where the disease has come from so that asymptomatic carriers can be found.


When blisters are present, the virus is highly contagious and the couple should avoid sex during an attack and until lesions have cleared.

Asymptomatic shedding makes avoidance of transmission difficult because it is not always possible to know when the virus is being shed. So, to answer this person’s question, there is still a chance of infection if the boyfriend does not have symptoms. There may be more asymptomatic virus shedding in the first year after acquiring herpes simplex type II, and in individuals who have frequent recurrences.

Condoms can be used to try to prevent transmission, but the area involved often does not lie within the area covered by the condom.

This couple needs to discuss the risks further and come to an informed decision together.

About the author

Sarah Pillai is a lead clinician at Central London Community Healthcare NHS Trust

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Citation: The Pharmaceutical Journal URI: 11105921

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