Cold Sore
A small skin blister also known as a “fever blister” that appears on the mouth during a cold. This is extremely common and is usually first transmitted during childhood. The term “fever blister” comes from the fact that such blisters often appeared during the high fevers of infectious illnesses before the invention of antibiotics.
Cold sores are harmless in healthy children and adults, although they are painful to the touch and can be unattractive. They are similar, but not identical, to “canker sores,” which also appear on the mouth. Both usually cause small sores to develop in the mouth that heal within two weeks. However, canker sores are not usually preceded by a blister. Canker sores are usually larger than fever blisters, but they do not usually merge to form one large sore as fever blisters do. Finally, canker sores usually erupt on movable parts of the mouth (such as the tongue and the cheek or lip linings), whereas cold sores usually appear on the gums, roof of the mouth, lips, or nostrils.
People are most infectious when the sores first appear, but the cold virus is shed in the saliva for a long time (up to two months after the sores have healed). It can be spread to others during this entire time. Patients with an active cold sore should limit contact with newborns or anyone else with a weakened immune system.
Causes
Cold sores are caused by the contagious HERPES simplex virus. The viral strain usually responsible for cold sores is herpes simplex Type I (HSVI); up to 90 percent of all people around the world carry this virus. This strain usually appears on the mouth, lips, and face.
The virus is highly contagious when the blisters are present; it is often transmitted by kissing. The virus can also be spread by children who touch their blisters and then touch other children. About 10 percent of oral herpes cases in adults are acquired by oral-genital sex with a person with active genital herpes.
Most people have their first infection before age 10, although most will not have symptoms. About 15 percent will go on to develop many fluid-filled blisters inside and outside the mouth about five days after exposure, together with fever, swollen neck, and aches. This is followed by a yellow crust that forms over the blister, healing without scars in about two weeks. Once the infection occurs, the virus remains in a nerve located near the cheekbone. There it may remain, forever inactive, or it may travel down the nerve to the surface of the skin to cause a new blister.
Recurrent attacks tend to be less severe.
Cold sores tend to appear when the victim is stressed, exposed to sunlight, a cold wind, or another infection, or feels run down. Women tend to experience more cold sores around their menstrual periods, but some people are afflicted at regular intervals throughout the year. People with compromised immune systems may experience prolonged attacks.
One study suggests that the tendency for relapses might be inherited.
Symptoms
The first attack may not even be noticed; the first infection in childhood usually causes no symptoms. However, about 10 percent of newly infected children experience a mild to fairly severe illness with fever, tiredness, and several painful cold sores in the mouth and throat.
Subsequent outbreaks are often signaled by a tingling in the lips, followed by a small water-filled blister on a red base that soon grows, causing itching and soreness. Within a few days the blisters burst, encrust, and then disappear within a week. The virus then retreats back along the nerve where it lies dormant in the nerve cell; in some patients, however, the virus is constantly reactivated.
Treatment
There is no cure for recurrent fever blisters. For mild symptoms, the sore should be kept clean and dry and it will heal itself. For particularly virulent outbreaks, the antiviral drug ACYCLOVIR or idoxuridine paint may relieve symptoms. Otherwise, there are a range of nonprescription drugs available containing some numbing agent (such as camphor or phenol) that also contain an emollient to reduce cracking.
Some studies have suggested that zinc may help prevent outbreaks because the zinc interferes with herpes viral replication. Studies found that both zinc gluconate and zinc sulfate helped speed up healing time, but zinc gluconate was less irritating to the skin. Both zinc products are available at health food stores.
Sores can be protected with a dab of petroleum jelly (applied with a clean cotton swab); do not dip the swab that touched the affected area back into the jar. Patients should avoid drinks with a high acid content (such as orange juice).
Complications
Anyone with an impaired immune system is at risk of complications; the virus may spread throughout the body, causing a severe illness.
Prevention
While there is no effective preventive treatment, some patients find that using a lip salve before going out in the sun prevents outbreaks. Research has shown that the virus can live up to seven days on a toothbrush, causing a reinfection after the sore heals. Once a sore develops, an infected toothbrush can also lead to multiple sores, so a new toothbrush should be used during the outbreak. Once the sore has healed completely, a new toothbrush should be used. It is also better to use small tubes of toothpaste, since the paste can transmit germs, too. Using small tubes of paste will mean that you throw the tubes away more quickly.
An infected individual should not touch sores, which could spread the virus to new sites (such as the eyes or the genitals). Kissing should be avoided during an outbreak.
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