It should not be confused with conditions caused by other viruses in the herpesviridae family such as herpes zoster, which is caused by varicella zoster virus. The differential diagnosis includes hand, foot and mouth disease due to similar lesions on the skin. Lymphangioma circumscriptum and dermatitis herpetiformis may also have a similar appearance.

Pain, sore lips, burning sensation, tingling, or itching occurs at the infection site before the sores appear. These are the early symptoms (prodrome). Sometimes these symptoms happen prior to the appearance of sores, bumps, pimple-like lesions, or blisters (herpes or herpetic stomatitis). Thereafter, clusters or groups of painful blisters (also termed fever blisters) or vesicles erupt or ooze with a clear to yellowish fluid that may develop into a yellowish crust. These blisters break down rapidly and appear as tiny, shallow gray ulcers on a red base. Fever blisters are smaller than canker sores. A few days later, they become crusted or scabbed and appear drier and more yellow.
Some people have recurrent outbreaks with the so-called “classic” blister-like herpes lesions that crust over, or with painful sores. In recurrent herpes, however, this process usually takes about half the time it does in first episodes. In addition, many people have very subtle forms of recurrent herpes that heal up in a matter of days. And lastly, herpes is capable of reactivating without producing any visible lesions (asymptomatic reactivation).
Herpes virus type 1 (HSV-1) is the cause of cold sores or fever blisters around the mouth. Usually, the sores or blisters can show up on the outside of the mouth or on the lips. But sometimes, they can be inside the mouth, on the face, nose, cheeks or fingers. HSV-1 can also lead to infection of the genitals, called genital herpes. This occurs when you have a cold sore and perform oral sex on another person. HSV-1 infections are highly contagious. Apart from oral-genital contact, they can be spread through skin-to-skin contact. If you come into contact with a person or a thing that carries HSV-1, you will be likely to get it, too. Often, people get HSV-1 from kissing someone with a cold sore or when they share eating utensils, razors, or towels.
^ Nasser M, Fedorowicz Z, Khoshnevisan MH, Shahiri Tabarestani M (October 2008). "Acyclovir for treating primary herpetic gingivostomatitis". The Cochrane Database of Systematic Reviews (4): CD006700. doi:10.1002/14651858.CD006700.pub2. PMID 18843726. (Retracted, see doi:10.1002/14651858.cd006700.pub3. If this is an intentional citation to a retracted paper, please replace {{Retracted}} with {{Retracted|intentional=yes}}.)
Herpes, whether on the mouth or genitals, is caused by a family of over 70 related viruses. These viral infections cause small, fluid-filled blisters to develop on the skin and mucous membranes. There are actually eight different types of herpes simplex viruses that both children and adults can acquire, but two are by far the most common: HSV-1 and HSV-2.

If you are pregnant and have genital herpes, it is very important for you to go to prenatal care visits. Tell your doctor if you have ever had symptoms of, or have been diagnosed with, genital herpes. Also tell your doctor if you have ever been exposed to genital herpes. There is some research that suggests that genital herpes infection may lead to miscarriage, or could make it more likely for you to deliver your baby too early.


Herpes “triggers” (determining exactly what leads to an outbreak) are highly individual, but with time, many people learn to recognize, and sometimes avoid, factors that seem to reactivate HSV in their own bodies. Illness, poor diet, emotional or physical stress, friction in the genital area, prolonged exposure to ultraviolet light (commonly for oral herpes, such as a beach trip or skiing weekend), surgical trauma, and steroidal medication (such as asthma treatment) may trigger a herpes outbreak.
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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