After exposure to the virus, many people experience a so called primary infection which is typically associated with sores on or around the genitals or the anus. During a primary infection some people experience pain in the groins or a mild fever. Not all infected individuals experience a primary infection or show any symptoms at all, but they can still pass the disease on to other people.
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.