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Herpes simplex virus (HSV; cold sores; genital sores; genital ulcers)

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What is Herpes Simplex Virus (HSV; Cold Sores; Genital Sores; Genital Ulcers)

There are two different strains of herpes simplex viruses: herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2).

Herpes simplex virus type 1 (HSV-1) is usually associated with infections of the lips, mouth, and face. It is the most common herpes simplex virus among the general population and is usually acquired in childhood. HSV-1 often causes lesions inside the mouth such as cold sores (fever blisters) and is transmitted by contact with infected saliva. By adulthood, up to 90% of individuals will have antibodies to HSV-1.

Herpes simplex virus 2 (HSV-2) is sexually transmitted and is usually associated with genital ulcers or sores. Individuals may, however, harbor HSV-2 and not have developed any symptoms. Up to 30% of US adults have antibodies against HSV.

Cross-infection of type 1 and 2 viruses may occur from oral-genital contact. In addition to oral and genital lesions, the virus can also lead to complications such as meningoencephalitis (infection of the lining of the brain and the brain itself) or cause infection of the eye – in particular the conjunctiva and cornea.


This is the most common sexually transmitted infection worldwide. It is most prevalent in 16-24 males and females.

Risk Factors

Unprotected sex with an infected individual or coming into direct contact with body fluids (eg. blood). Recurrences of herpes may be precipitated by overexposure to sunlight, fever, stress, acute illness, and medications or conditions that weaken the immune system (such as cancer, HIV/AIDS). and use of corticosteroids).


The disease is transmitted during close contact with a person who is shedding the virus. Most genital herpes is due to HSV type 2 although genital contact with oral lesions caused by HSV-1 can also produce genital infection.

How is it Diagnosed?

Swabs should be taken from the lesions and the virus should be able to be isolated to confirm a diagnosis of HSV.


The oral or genital lesions usually heal on their own in 7 to 10 days unless an individual has an underlying condition that weakens the immune system, in which case the infection may be more severe and last longer.

Once infected, the virus stays in the body for the rest of a person’s life and recurrences of active infection may occur. Recurrences may be precipitated by overexposure to sunlight, fever, stress, acute illness, and medications or conditions that weaken the immune system (such as cancer, HIV/AIDS, or use of corticosteroids).

How is it Treated?

Primary HSV

Saltwater bathing or sitting in a warm bath may helf the patient to pass urine more comfortly. If the lesions are still moist, aciclovir, famciclovir and valaciclovir can be useful (but useless if the lesions are crusting).

Rest, analgesia and antipyretics should be advised. If HSV encephalitis is suspected, patients may need to be admitted to hospital and administered with aciclovir intravenously.


Recurrent attacks are usually less severe and can be helped by saltwater bathing. However, psychological morbidity is common and recurrence imposes strain on relationships and patients need considerable support. Patients with frequent recurrences may be given long-term suppressive aciclovir therapy (400mg twice daily) or 500mg valaciclovir daily for 6-12 months to reduce the frequency of attacks.

Infection during pregnancy may spread to the neonate either transplacentally or via the birth canal (especially if it is primary HSV). Treatment in the 1st or 2nd trimester will depend on the mother’s condition. Aciclovir may be prescribed in standard doses. Aciclovir therapy during the last 4 weeks of pregnancy may prevent recurrence at term. Primary acquisition during the third trimester or at term with high levels of viral shedding usually leads to delivery by caesarean section. For women with previous infection, the risk of baby acquiring HSV from the birth canal is low. Usually only women with genital lesions at the onset of labour deliver by caesarean section.

Sexual intercourse should be avoided when infectious lesions are present. Condoms may not provide an effective barrier as lesions may occur outside the areas covered. Sexual partners should be examined and may need to be informed on how to avoid infection.

More information

Sexually transmitted infections (STIs)For more information on different types of sexually transmitted infections, prevention of STIs, treatments and effects on fertility, see Sexually transmitted infections (STIs).



  1. Kumar P, Clark M (eds). Clinical Medicine (5th edition). Edinburgh: WB Saunders Company; 2002. Book
  2. Cold sores [online]. Bethesda, MD: National Institutes of Health Medline Plus; 2003 [cited 1 August 2003]. Available from: [URL Link]
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Posted On: 1 August, 2003
Modified On: 14 May, 2018


Created by: myVMC