Doctor's Notes on Oral Herpes (HSV-1) (Herpes of the Mouth)
Oral herpes refers to Herpes simplex virus infections of the mouth. The Herpes simplex virus (HSV) can cause infections that affect the mouth, face, genitals, skin, buttocks, and the anal area. HSY type 1 (HSV-1) more commonly infects the mouth than HSV-2, which most commonly affects the genital area, but both types can infect any location. HSV-1 infection of the mouth produces the condition commonly referred to as a cold sore.
The characteristic appearance of oral herpes is a cluster of painful blisters on a base of red skin. These blisters appear to be filled with a clear fluid. When they dry up, there is a crust or scab that lasts for days to weeks. Associated symptoms can include a tingling or a burning sensation in the area that occurs before the actual outbreak. Itching can be another associated symptom.
Oral Herpes (HSV-1) (Herpes of the Mouth) Symptoms
- Incubation period: For HSV-1, the amount of time between contact with the virus and the appearance of symptoms, the incubation period, is two to 12 days. Most people average about three to six days.
- Duration of illness: Signs and symptoms will last two to three weeks (healing time). Fever, tiredness, muscle aches, and irritability may occur.
- 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.
- Oral sores: The most intense pain caused by these sores occurs at the onset and can make eating and drinking difficult.
- The sores can occur on the lips, gums, throat (causing a sore throat), the front of or under the tongue, the inside of the cheeks, and the roof of the mouth.
- They can also extend down the chin and neck.
- The gums can become mildly swollen, red-colored, and may bleed.
- Neck lymph nodes often swell and become painful.
- People in their teens and 20s can develop a painful throat with shallow ulcers and a grayish coating on the tonsils.
Oral Herpes (HSV-1) (Herpes of the Mouth) Causes
Herpes simplex virus (HSV) is a DNA virus that causes sores in and around the mouth. Two herpes subtypes may cause these sores.
- Herpes simplex virus (type 1, herpes-1, or HSV-1) causes about 80% of cases of oral herpes infections. There is no evidence that HSV-1 viruses mutate into HSV-2 viruses.
- Another herpes simplex virus (type 2, herpes-2 or HSV-2) causes the other 20% and causes the majority of genital herpes infections.
These herpes viruses enter the body through small cuts, abrasions, or breaks in the skin or mucous membranes. The incubation period for herpes simplex infections is about three to six days. Transmission (spread) of the virus is person to person and more likely to occur if blisters or lesions are present. The majority enter after an uninfected person has direct contact with someone carrying the virus (either with or without noticeable lesions). Simply touching an infected person is often the way children get exposed. Adolescents and adults frequently get exposed by skin contact but may get their first exposure by kissing or sexual contact (oral and/or genital contact), especially for HSV-2. Statistical studies suggest that about 80%-90% of people in the U.S. have been exposed to HSV-1 and about 30% have been exposed to HSV-2. Usually, the contagious period continues until lesions heal. Some people (estimated from 30%-50%) occasionally shed herpes virus while having few or no associated symptoms or signs.
Oral lesions (and genital lesions) can reoccur. This happens because the HSV viruses are still alive but exist in nerve cells in a quiet, inactive (dormant) state. Occasionally, conditions in the body (see stage 3 above) allow the HSV to actively multiply, resulting in a new crop of lesions.
The HSV viruses multiply in the human cell by overtaking and utilizing most of the human cells functions. One of the HSV steps in multiplication is to take control of the human cell's nucleus and alter its structure. The altered nucleus (enlarged and lobulated or multinucleated) is what actually is used to help diagnose herpes simplex infections by microscopic examination. The reason sores appear is because as they mature the many HSV particles rupture the human cell's membrane as they break out of the cell.
Transmission of HSV-1 occurs by direct exposure to saliva or droplets formed in the breath of infected individuals. In addition, skin contact with the lesions on an infected individual can spread the disease to another individual. Although close personal contact is usually required for transmission of the virus, it is possible to transmit HSV-1 when people share toothbrushes, drinking glasses, or eating utensils.
Cold sores, also known as fever blisters, can make you feel uncomfortable and self-conscious. What’s worse, it seems like some people get them while others are apparently spared. Even though there is no cure, treatments are available to shorten the duration of the symptoms or bring some relief. This guide will show you how to recognize and manage cold sores.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.