Patient - General education & information

Insight into causes, treatment, and prevention

• What are fever blisters and cold sores?
• What are canker sores?
• When should a physician be consulted?
• and more...

Oral lesions (mouth sores) make it painful to eat and talk. Two of the most common recurrent oral lesions are fever blisters (also known as cold sores) and canker sores. Though similar, fever blisters and canker sores have important differences.

What are fever blisters?

Fever blisters are fluid-filled blisters that commonly occur on the lips. They also can occur on the gums and roof of the mouth (hard palate), but this is rare. Fever blisters are usually painful; pain may precede the appearance of the lesion by a few days. The blisters rupture within hours, then crust over. They last about seven to ten days.

Why do fever blisters reoccur?

Fever blisters result from a herpes simplex virus that becomes active. This virus is latent (dormant) in afflicted people, but can be activated by conditions such as stress, fever, trauma, hormonal changes, and exposure to sunlight. When lesions reappear, they tend to form in the same location.

Are fever blisters contagious?

Yes, the time from blister rupture until the sore is completely healed is the time of greatest risk for spread of infection. The virus can spread to the afflicted person’s eyes and genitalia, as well as to other people.

How are fever blisters treated?

Treatment consists of coating the lesions with a protective barrier ointment containing an antiviral agent, for example 5% acyclovir ointment. While there is no cure now, scientists are trying to develop one, so hopefully fever blisters will be a curable disorder in the future.

Tips to prevent spreading fever blisters

• Avoid mucous membrane contact when a lesion is present.
• Do not squeeze, pinch, or pick the blisters.
• Wash hands carefully before touching eyes, genital area, or another person.

Note: Despite all caution, it is possible to transmit herpes virus even when no blisters are present.

What are canker sores?

Canker sores (also called aphthous ulcers) are different than fever blisters. They are small, red or white, shallow ulcers occurring on the tongue, soft palate, or inside the lips and cheeks; they do not occur in the roof of the mouth or the gums. They are quite painful, and usually last 5-10 days.

Who is most likely to get canker sores, and what causes them?

Eighty percent of the U.S. population between the ages of 10 to 20, most often women, get canker sores. The best available evidence suggests that canker sores result from an altered local immune response associated with stress, trauma, or irritation. Acidic foods (e.g., tomatoes, citrus fruits, and some nuts) are known to cause irritation in some patients.

Are canker sores contagious? How are they treated?

Because they are not caused by bacteria or viral agents, they are not contagious and cannot be spread locally or to anyone else. Treatment is directed toward relieving discomfort and guarding against infection. A topical corticosteroid preparation such as triamcinolone dental paste (Kenalog in Orabase 0.1%®) is helpful.

When should a physician be consulted?

Consider consulting a physician if a mouth sore has not healed within two weeks. Mouth sores offer an easy way for germs and viruses to get into the body, so it is easy for infections to develop.

People who consume alcohol, smokers, smokeless tobacco users, chemotherapy or radiation patients, bone marrow or stem cell recipients, or patients with weak immune systems should also consider having regular oral screenings by a physician. The first sign of oral cancer is a mouth sore that does not heal.

What kind of screenings are performed?

The physician will most likely examine the head, face, neck, lips, gums, and high-risk areas inside the mouth, such as the floor of the mouth, the area under the tongue, the front and sides of the tongue, and the roof of the mouth or soft palate. If a suspicious lesion is found, the physician may recommend collecting and testing soft tissue from the oral cavity.

What are other types of oral lesions to be concerned about?

Leukoplakia - A thick, whitish-color patch that forms on the inside of the cheeks, gums, or tongue. These patches are caused by excess cell growth and are common among tobacco users. They can result from irritations such as ill-fitting dentures or the habit of chewing on the inside of the cheek. Leukoplakia can progress to cancer.

Candidiasis - A fungal infection (also called moniliasis or oral thrush) that occurs when yeast reproduce in large numbers. It is common among denture wearers and most often occurs in people who are very young, elderly, debilitated by disease, or who have a problem with their immune system. People who have dry mouth syndrome are very susceptible to candidiasis. Candida may flourish after antibiotic treatment, which can decrease normal bacteria in the mouth.

Hairy tongue - A relatively rare condition caused by the elongation of the taste buds. It can be caused by poor oral hygiene, chronic oral irritation, or smoking.

Torus palatinus - A hard bony growth in the center of the roof of the mouth (palate). It commonly occurs in females over the age of 30 and rarely needs treatment. A torus palatinus is often seen in patients who suffer from tooth grinding. Occasionally it is removed for the proper fitting of dentures.

Oral cancer - It may appear as a white or red patch of tissue in the mouth, or a small ulcer that looks like a common canker sore. Other than the lips, the most common areas for oral cancer to develop are on the tongue and the floor of the mouth. Other symptoms include a lump or mass that can be felt inside the mouth or neck; pain or difficulty in swallowing, speaking, or chewing; any wart-like mass; hoarseness that lasts for more than two weeks; or any numbness in the oral/facial region.

Tips to prevent mouth sores

• Stop smoking.
• Reduce stress.
• Avoid injury to the mouth caused by hard tooth brushing, hard foods, braces, or dentures.
• Chew slowly.
• Practice good dental hygiene, including regular visits to the dentist.
• Eat a well-balanced diet.
• Identify and eliminate food sensitivities.
• Drink plenty of water.
• Avoid very hot food or beverages.
• Follow nutritional guidelines for multivitamin supplements.