Herpes viruses typically infect the oral or genital mucosa. When herpes affects the mouth, it causes the typical "cold sores," which are painful sores or blisters that form on the lips, mouth, or gums. Prior to the development of the blisters, there may be a prodrome (early symptoms indicating onset of a particular disease) consisting of an itching, burning, or tingling sensation in the affected area. The virus remains dormant in the nervous system throughout life, and this is the reason that cold sores often recur in the same location.
Patients with genital herpes have reported that outbreaks or episodes typically diminish through the years. Early prodromal symptoms, or warning signals, that are followed by outbreaks. These prodromal symptoms often include mild tingling or shooting pains in the legs, hips and buttocks, and can last from 2 hours to 2 days. After the prodromal symptoms occur the blisters develop into painful red spots, which then evolve into yellowish, clear fluid-filled blisters after a day or two. These blisters burst or break and leave ulcers that usually heal in about 10 days. In women, blisters can develop inside the vagina and cause painful urination.
Herpes simplex viruses -- more commonly known as herpes -- are categorized into two types: herpes type 1 (HSV-1, or oral herpes) and herpes type 2 (HSV-2, or genital herpes). Most commonly, herpes type 1 causes sores around the mouth and lips (sometimes called fever blisters or cold sores). HSV-1 can cause genital herpes, but most cases of genital herpes are caused by herpes type 2. In HSV-2, the infected person may have sores around the genitals or rectum. Although HSV-2 sores may occur in other locations, these sores usually are found below the waist.
A doctor will base a presumptive diagnosis on information provided by the patient and on the physical examination. The characteristic appearance of the herpes sores leaves little doubt about the diagnosis, so the typical appearance of the sores is key to the diagnosis. This appearance helps distinguish oral herpes from oral thrush, shingles, gonorrhea, and syphilis. In addition, chapped or sunburned lips can resemble oral herpes, but the tissue stain (Tzanck smear, see below) shows no virus-induced cell changes. Further testing is usually not necessary but is sometimes done.