Particularly when someone is on suppressive antiviral medication and practicing safer sex, risk of transmission can be greatly reduced. Cullins suggests female condoms (condoms that go inside the vagina and cover most of the vulva, though it's important to note that not all people with vaginas are female) to provide the most protection against transmission, though condoms that go over the penis will protect what they cover.
^ McNeil DG. Topical Tenofovir, a Microbicide Effective against HIV, Inhibits Herpes Simplex Virus-2 Replication Archived 2017-04-09 at the Wayback Machine. NY Times. Research article: Andrei G; Lisco A; Vanpouille C; et al. (October 2011). "Topical Tenofovir, a Microbicide Effective against HIV, Inhibits Herpes Simplex Virus-2 Replication". Cell Host. 10 (4): 379–89. doi:10.1016/j.chom.2011.08.015. PMC 3201796. PMID 22018238.
Not every person with a herpes infection actually experiences breakouts of cold sores throughout his or her lifetime or even after initially becoming infected. How often someone has a herpes cold sore outbreak, how severe the outbreaks are, how contagious someone is after infection and how long the sores take to heal all depend on someone’s individual immune response.
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.