If you think you have or have been exposed to herpes you should see your primary care provider for follow up, screening, and possible treatment. Many providers today will not test unless you have symptoms of an outbreak, as often tests come back as false positive and the CDC has concluded that false positives cause psychological trauma to those tested. There is much debate on if you should test without symptoms or not, others say it is unethical to not be aware of your current STD status and risk infecting 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.