Herpes simplex

Herpes simplex is a common viral infection, caused by herpes simplex virus types 1 and 2, that causes painful blisters or ulcers around the mouth, genitals or skin. It occurs worldwide, most adults carry type 1, and many people have mild or no symptoms yet can still pass it on. Type 1 spreads mainly through oral contact and is the usual cause of cold sores, though it can also infect the genitals, whereas type 2 spreads by sexual contact; newborns can acquire it at delivery. Episodes often start with tingling, itching or burning, then blisters burst and crust over, and a first infection may bring fever, body aches and swollen lymph nodes. Testing fluid swabbed from a blister or sore identifies the virus. It is treatable but not curable, because the virus persists in nerve cells and reactivates; antiviral medicines such as acyclovir lessen episodes, and analgesics ease pain.

Seek urgent care for a high fever with a stiff neck, rash, confusion, difficulty breathing, or fever after travel to a malaria area. See a doctor when a fever lasts more than three days, when symptoms return after treatment, or when you may have been exposed to an infection that needs testing. Call the local emergency number for any symptom that is sudden and severe. This page is a reference for healthcare professionals and does not replace an assessment.