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.
'Using condoms or dams can help to protect against STIs, but herpes can also be passed on by skin-to-skin contact with the affected area, so it’s strongly recommended that you don’t have sex during this time,' she adds. 'This includes direct genital contact or skin-to-skin contact with the affected area, and doesn’t have to be penetrative sex,' says O’Sullivan.