What is herpes simplex infection?

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Herpes simplex infection is a sore or blister caused by the herpes simplex virus (HSV) that can occur on the face or the genital area. The blisters contain fluid that harbors the virus.
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Herpes simplex infection is a sore or blister caused by the herpes simplex virus (HSV) that can occur on the face or the genital area. The blisters contain fluid that harbors the virus.


Herpes simplex infection is caused when the virus is transmitted by person-to-person contact or by contact with contaminated items. HSV type 1 usually causes cold sores or blisters on the lips, while HSV type 2 is usually the cause of genital herpes. Kissing, oral sex, or other sexual acts may transmit the virus. Sharing infected items (fomites), such as lipstick, dishes, and towels, may also cause infection. Pregnant women may infect their fetuses during a vaginal birth.

Risk Factors

Exposure to someone with an active infection and contact with contaminated items are risk factors for infection with HSV. Newborns and persons who are stressed or who have a weak immune system are more at risk. Previous infection with herpes simplex is a risk factor in future infections. Unprotected sex is a risk factor for genital herpes.


The presence of small, painful blisters that are filled with fluid is the primary symptom of infection with HSV. A tingling or painful sensation may occur before blister development. Blister development may take a few weeks after exposure to the virus.

Screening and Diagnosis

There is no recommended routine screening test for the HSV. For cold sores, diagnosis is usually made based on symptoms. A physician will ask about previous cold sores, current stress levels, tingling or pain before the blister developed, and exposure to others with cold sores. For genital herpes, a herpes viral culture of the fluid in the blister may be used in addition to the physician’s examination. A herpesvirus antigen test involves the use of a microscope to find markers on cells that indicate infection. A polymerase chain reaction test can be used with fluids from sores, blood, or spinal fluid to look for genetic material and can determine if the virus is type 1 or type 2.

Treatment and Therapy

Outbreaks of herpes simplex infection may occur several times a year. Cold sores usually will clear up on their own or with over-the-counter treatments. Persons who have frequent cold sores, an impaired immune system, a cold sore that does not heal, or severe symptoms including pain, should contact a doctor. Oral antiviral drugs may be prescribed by the doctor if outbreaks are severe. Cold or warm cloths applied to the blister may ease the pain.

Genital herpes requires a visit to a physician. There is no treatment that can cure genital herpes, but medication is available to treat outbreaks and to suppress the virus.

Prevention and Outcomes

One should not share personal items with persons who have visible cold sores, should refrain from eating and drinking from shared plates and cups, and should use good handwashing technique. Genital herpes can be transmitted even when blisters are not present, so one should abstain from sexual contact when blisters are visible. Latex condoms, when correctly used, may reduce the risk of herpes simplex infection, but they cannot eliminate infection.


Gordon, Sara C., et al. “Viral Infections of the Mouth.” Available at http://emedicine.medscape.com/article/1079920-overview.

James, S. H., and R. J. Whitley. “Treatment of Herpes Simplex Virus Infections in Pediatric Patients: Current Status and Future Needs.” Clinical Pharmacology and Therapeutics 88 (2010): 720-724.

Kane, Melissa, and Tatyana Gotovkina. “Common Threads in Persistent Viral Infections.” Journal of Virology 84 (2010): 4116-4123.

Khare, Manjiri. “Infectious Disease in Pregnancy.” Current Obstetrics and Gynaecology 15 (2005): 149-156.

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