Oral herpes is also known commonly as cold sores and fever blisters but is different entity from oral canker sores although canker sores may sometimes be associated with HSV infection. Canker sores occur solely inside the mouth. Oral herpes occurs inside and around the mouth. Most of the time HSV-1 causes mouth symptoms and in a minority of cases it may also be responsible for genital symptoms. The opposite is true for HSV-2 – it causes genital symptoms in the majority of cases while only a few cases of HSV-2 infection will result in mouth symptoms. HSV-1 infection may be seen in all ages, including children, but when genital herpes is seen in children, sexual abuse needs to be a consideration.
Herpes infection of the genital tract is a sexually transmitted infection (sexually transmitted disease or STD). Like in the mouth area, herpes symptoms and signs include a painful, blistering rash around or on the genital or rectal areas. These lesions open and result in painful sores that can take two to four weeks to heal. The sores can sometimes cause painful urination. Recurrent outbreaks are typical, and the time between outbreaks varies among affected people and even within the same individual. Prior to an outbreak, a tingling, burning, or itching sensation may be present on the area of involved skin.
Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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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