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Genital herpes is usually caused by the Herpes simplex virus type 2 (HSV-2). A fifth of the infections are caused by the Herpes simplex virus type 1 (HSV-1). At least 20% of adults carry HSV-2 but most have no symptoms. After transmission, the Herpes simplex virus remains latent in the neural ganglia and can later recur.


During the first outbreak, symptoms are often mild or there may be no symptoms at all. Within 2 to 14 days, a cluster of itchy, burning, sore and clear blisters develop at the site of infection; these burst within hours or 1 to 2 days. The blister bases become crusted, and the signs of infection heal within 2 to 4 weeks without leaving scars. The first outbreak may also involve severe symptoms. These may include fever, headache, muscle pain, swelling of lymph nodes in the groin, and infection of the urethra.

The herpes virus will remain latent in the nerve nuclei in the spinal cord. The virus becomes active randomly and travels along the nerve to the genital mucosa, buttock, lumbar region or thigh forming a cluster of blisters that typically causes tingling. Systemic symptoms occur only seldom. Rare symptoms include infection of the urethra (if the blisters are inside the urethra), neuropathic pain in the affected area, and rash called erythema multiforme following the herpes activation. Many carriers of HSV-2 have no symptoms. In others, the virus can become active as many as 10 or more times a year for an unknown reason.

Diagnosing herpes

Diagnosing herpes is usually straightforward because of the clinical picture. In unclear cases, a swab sample will be taken from the blister or sore. The virus can then be diagnosed by a culture, antigen detection or nucleic acid amplification. Blood sampling can only determine whether the person has HSV-1 or HSV-2.


Pharmacies sell creams containing aciclovir and penciclovir for the treatment of oral herpes. There’s no evidence that they are effective against genital herpes. They may shorten the duration of new herpes outbreaks but do not prevent them.

When should you seek treatment?

You should see a doctor if:

  • the symptoms of genital herpes are severe or if you have difficulty urinating.
  • herpes recurs often, i.e. at least 6 times a year.
  • repeat outbreaks last for long periods of time or cause a lot of pain.


Genital herpes is particularly infectious during the symptomatic stage, but it can also be transmitted from a partner who has no symptoms or who is unaware of the infection. You should avoid intercourse during the blister stage until the blister bases are dry. You cannot get the virus through a condom, but the condom won’t give you full protection either, as you may get the virus from the skin and mucosa outside the condom. You should always use a condom in casual sex, as herpes can be transmitted during asymptomatic periods too. Oral herpes can be transmitted to the genital area during oral sex.

80% to 90% of frequent cases of genital herpes can be controlled by continuous aciclovir, valaciclovir or famciclovir medication taken by mouth. In rest of the cases, the symptoms are mild and appear seldom. Even a long-term use of medication is not harmful, but the medicines cannot eradicate the virus that remains latent in the neurons. The preventive treatment usually lasts from six months to two years.

Information sources: The Finnish Medical Society Duodecim: Terveysportti, Lääkärin tietokanta database

FSHS General Practitioner / 29 March 2022        

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