Herpes Simplex

Key facts

• Herpes simplex is a lifelong viral infection caused by HSV-1, which usually causes cold sores around the mouth, or HSV-2, the usual cause of genital herpes.
• After the first infection, the virus lies dormant in nerve tissue and can reactivate. Common triggers include stress, fever, illness, sunlight, hormonal change, and immune suppression.
• Antiviral medicines, aciclovir, valaciclovir and famciclovir, shorten outbreaks and reduce how often they recur; continuous suppressive therapy helps people with frequent recurrences.
• See a doctor promptly for severe or spreading sores, eye pain or visual change, or any outbreak in someone who is immunocompromised.

Outbreaks and what triggers them

After the first infection, the virus travels to nearby nerve tissue and lies dormant, reactivating from time to time throughout life. Common triggers include stress, fever, illness, strong sunlight, hormonal changes, and anything that weakens the immune system. Outbreaks typically begin with tingling or itching, followed by clusters of small fluid-filled blisters that crust over and heal within one to two weeks. Genital outbreaks can also cause discomfort when urinating.

Antiviral treatment

Antiviral medicines shorten the duration of outbreaks and reduce their frequency. The three standard options are aciclovir, valaciclovir, and famciclovir. Valaciclovir and famciclovir are absorbed more efficiently, so they need fewer daily doses. For people with frequent outbreaks, six or more a year, continuous suppressive therapy cuts recurrence rates significantly and also lowers the risk of passing the virus to a partner.

When to see a doctor

See a doctor promptly if sores are severe or spreading, if you have eye pain or visual changes suggesting ocular involvement, or if you are immunocompromised and develop any outbreak.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.