Want to know more about fever blisters and how to treat them?
We asked the National Institute of Dental and Craniofacial Research for straightforward advice.
We know: All About Cold Sores/Fever Blisters
What are fever blisters?
Fever blisters, or cold sores, are small sores that develop outside the mouth, on the lips, chin, cheeks or nostrils. (Sores inside the mouth are usually canker sores. See our article, All About Canker Sores for more information.) However, Fever blisters can also occur inside the mouth on the gums or roof. They are smaller than canker sores, heal more quickly and often begin as a blister.
What causes fever blisters?
Fever blisters are caused by a contagious virus called herpes simplex. There are two types of herpes simplex virus. Type 1 usually causes oral herpes, or fever blisters. Type 2 usually causes genital herpes. Although both type 1 and type 2 viruses can infect oral tissues, more than 95 percent of recurrent fever blister outbreaks are caused by the type 1 virus.
Herpes simplex virus is highly contagious when fever blisters are present, and the virus frequently is spread by kissing. Children often become infected by contact with parents, siblings or other close relatives who have fever blisters.
What happens once you have the virus in your body?
Once a person is infected with oral herpes, the virus remains in a nerve located near the cheekbone. It may stay permanently inactive in this site, or it may occasionally travel down the nerve to the skin surface, causing a recurrence of fever blisters. Recurring blisters usually erupt at the outside edge of the lip or the edge of the nostril, but can also occur on the chin, cheeks, or inside the mouth.
What causes a recurrence of fever blisters?
Several factors weaken the body's defenses and trigger an outbreak of herpes. These include emotional stress, fever, illness, injury and exposure to sunlight. Many women have recurrences only during menstruation. One study indicates that susceptibility to herpes recurrences is inherited.
What are the treatments for fever blisters?
Currently there is no cure for fever blisters. Some medications can relieve some of the pain and discomfort associated with the sores, however. These include ointments that numb the blisters, antibiotics that control secondary bacterial infections, and ointments that soften the crusts of the sores.
What can the patient do?
If fever blisters erupt, keep them clean and dry to prevent bacterial infections. Eat a soft, bland diet to avoid irritating the sores and surrounding sensitive areas. Be careful not to touch the sores and spread the virus to new sites, such as the eyes or genitals. To make sure you do not infect others, avoid kissing them or touching the sores and then touching another person.
There is good news for people whose fever blister outbreaks are triggered by sunlight. Scientists have confirmed that sunscreen on the lips can prevent sun-induced recurrences of herpes. They recommend applying the sunscreen before going outside and reapplying it frequently during sun exposure.
People whose cold sores appear in response to stress should try to avoid stressful situations. Some investigators have suggested adding lysine to the diet or eliminating foods such as nuts, chocolate, seeds or gelatin. These measures have not, however, been proven effective in controlled studies.
Is there a vaccine for fever blisters?
Currently there is no vaccine for herpes simplex virus available to the public. Many research laboratories, however, are working on this approach to preventing fever blisters.