Human herpes virus 1 (HHV1) is also known as herpes simplex virus 1 (HSV1). It is typically the cause of cold sores around the mouth. HHV1 can also lead to infection in the genital area causing genital herpes usually through oral-genital contact, such as during oral sex. HHV1 infections are contagious and are usually spread from skin-to-skin contact with an infected person through small breaks in the skin or mucous membrane. The HHV1 virus is more likely to be spread through things like sharing eating utensils, razors, and towels from a person who has an active lesion.
The causes of reactivation are uncertain, but several potential triggers have been documented. A 2009 study showed the protein VP16 plays a key role in reactivation of the dormant virus.[71] Changes in the immune system during menstruation may play a role in HSV-1 reactivation.[72][73] Concurrent infections, such as viral upper respiratory tract infection or other febrile diseases, can cause outbreaks. Reactivation due to other infections is the likely source of the historic terms 'cold sore' and 'fever blister'.

Prodrome: Early in the phase of reactivation (also called an outbreak), many people experience an itching, tingling, or painful feeling in the area where their recurrent lesions will develop. This sort of warning symptom – called a “prodrome” – often comes a day or two before lesions appear. To be on the safe side, it’s best to assume virus is active (and, therefore, can be spread through direct skin-to-skin contact) during these times.

Prodrome: Early in the phase of reactivation (also called an outbreak), many people experience an itching, tingling, or painful feeling in the area where their recurrent lesions will develop. This sort of warning symptom – called a “prodrome” – often comes a day or two before lesions appear. To be on the safe side, it’s best to assume virus is active (and, therefore, can be spread through direct skin-to-skin contact) during these times.


Avoid touching any sores you have. If you do, wash your hands with soap and water. You should avoid sex while you have sores, and use a male or female condom or dental dam with your partner if sex occurs despite intentions to not have sex. Herpes is most contagious during an outbreak, but it’s also possible to spread herpes when no symptoms are present.
Herpes infection can be passed from you to your unborn child before birth but is more commonly passed to your infant during delivery. This can lead to a potentially deadly infection in your baby (called neonatal herpes). It is important that you avoid getting herpes during pregnancy. If you are pregnant and have genital herpes, you may be offered anti-herpes medicine towards the end of your pregnancy. This medicine may reduce your risk of having signs or symptoms of genital herpes at the time of delivery. At the time of delivery, your doctor should carefully examine you for herpes sores. If you have herpes symptoms at delivery, a ‘C-section’ is usually performed.
Avoid physical contact with anyone who has visible blisters and sores, and don't share towels or anything that may have come into contact with the sores. "It is also important that before you have any intimate contact with anyone you ask them about their sexual health, whether they have a herpes infection or have ever had any other sexually transmitted infection," Michael advises. "This is because statistically, people who have had an STI are more likely to be infected with the herpes virus. Using condoms and dental dams can also help reduce your risk of catching oral herpes."
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.
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