Genital Herpes

The herpes simplex virus (HSV) is commonly responsible for both cold sores (herpes labialis) and genital herpes. There are two main strains, HSV-1 and HSV-2. Both strains are common in the UK, and many people are infected without experiencing any symptoms. After an initial infection, the virus becomes latent in the associated sensory nerve ganglia. Typically this is the trigeminal nerve ganglion with cold sores and the sacral nerve ganglia with genital herpes.

The herpes simplex virus can also cause aphthous ulcers (small painful oral sores in the mouth), herpes keratitis (inflammation of the cornea in the eye) and herpetic whitlow (a painful skin lesion on a finger or thumb).

The herpes simplex virus is spread through direct contact with affected mucous membranes or viral shedding in mucous secretions. The virus can be shed even when no symptoms are present, meaning it can be contracted from asymptomatic individuals. Asymptomatic shedding is more common in the first 12 months of infection and where recurrent symptoms are present.

HSV-1 is most associated with cold sores. It is often contracted initially in childhood (before five years), remains dormant in the trigeminal nerve ganglion and reactivates as cold sores, particularly in times of stress. Genital herpes caused by HSV-1 is usually contracted through oro-genital sex, where the virus spreads from a person with an oral infection to the person that develops a genital infection.

HSV-2 typically causes genital herpes and is mostly a sexually transmitted infection. It can also cause lesions in the mouth.


Presentation of Genital Herpes

Patients affected by herpes simplex may display no symptoms, or develop symptoms months or years after an initial infection when the latent virus is reactivated.

The symptoms of an initial infection with genital herpes usually appear within two weeks. The initial episode is often the most severe, and recurrent episodes are milder.

Signs and symptoms include:

  • Ulcers or blistering lesions affecting the genital area
  • Neuropathic type pain (tingling, burning or shooting)
  • Flu-like symptoms (e.g. fatigue and headaches)
  • Dysuria (painful urination)
  • Inguinal lymphadenopathy

Symptoms can last three weeks in a primary infection. Recurrent episodes are usually milder and resolve more quickly.



Ask about sexual contacts, including those with cold sores, to establish a possible source of transmission. They may have caught the infection from someone unaware they are infected and not experiencing any symptoms.

The diagnosis can be made clinically based on the history and examination findings.

A viral PCR swab from a lesion can confirm the diagnosis and causative organism.



Where appropriate, patients should be referred to a genitourinary medicine (GUM) specialist service.

Aciclovir is used to treat genital herpes. There are various aciclovir regimes listed in the BNF, depending on the individual circumstances. Alternatives are valaciclovir and famciclovir.

Additional measures, including to manage the symptoms include:

  • Paracetamol
  • Topical lidocaine 2% gel (e.g. Instillagel)
  • Cleaning with warm salt water
  • Topical vaseline
  • Additional oral fluids
  • Wear loose clothing
  • Avoid intercourse with symptoms


Pregnancy and Genital Herpes

Genital herpes is not known to cause pregnancy-related complications or congenital abnormalities. The main issue with genital herpes during pregnancy is the risk of neonatal herpes simplex infection contracted during labour and delivery. Neonatal herpes simplex infection has high morbidity and mortality. Neonatal infection should be avoided as much as possible and treated early if identified.

After an initial infection with genital herpes, the woman will develop antibodies to the virus. During pregnancy, these antibodies can cross the placenta into the fetus. This gives the fetus passive immunity to the virus, and protects the baby during labour and delivery.

Management of genital herpes in pregnancy depends on whether it is the first episode of genital herpes (primary infection) or recurrent genital herpes. There are guidelines on genital herpes from the RCOG (2014). Always check local and national guidelines when treating patients. Aciclovir is not known to be harmful in pregnancy.

Primary genital herpes contracted before 28 weeks gestation is treated with aciclovir during the initial infection. This is followed by regular prophylactic aciclovir starting from 36 weeks gestation onwards to reduce the risk of genital lesions during labour and delivery. Women that are asymptomatic at delivery can have a vaginal delivery (provided it is more than six weeks after the initial infection). Caesarean section is recommended when symptoms are present.

Primary genital herpes contracted after 28 weeks gestation is treated with aciclovir during the initial infection followed immediately by regular prophylactic aciclovirCaesarean section is recommended in all cases to reduce the risk of neonatal infection.

Recurrent genital herpes in pregnancy, where the woman is known to have genital herpes before the pregnancy, carries a low risk of neonatal infection (0-3%), even if the lesions are present during delivery. Regular prophylactic aciclovir is considered from 36 weeks gestation to reduce the risk of symptoms at the time of delivery.


Last updated August 2020