Mouth Sores

MOUTH SORES (Fever Blisters and Canker Sores)

If you have been bothered by a sore in your mouth that made it painful to eat and talk, you are not alone. Many otherwise healthy people suffer from recurrent mouth sores. Causes can roughly be divided into infectious or autoimmune. The causes or infection are mainly viral but can include bacteria or fungi. Rarely, a cancer will present as a non-healing mouth sore, so consultation with a specialist is important.

Two of the most common recurrent oral lesions are fever blisters (also called cold sores) and canker sores (aphthous ulcers). When they occur in the mouth, it may be difficult to distinguish one from the other. Since the treatment and cause of these two sores are different, it is extremely important to know which is which.

What Are Fever Blisters (Cold Sores)?

These are common names for fluid filled blisters that commonly occur on the lips. This is termed recurrent herpes labialis. They also can occur in the mouth, particularly on the gums and roof of the mouth (hard palate)-(immobile mucosa) in older children or adults, but this is rare. This is termed primary herpetic gingivostomatitis. Fever blisters are usually painful; in fact, the pain may precede the appearance of the lesion by a few days. They are often accompanied by a fever. The blisters rupture within hours, then crust over. They last about 7-10 days.


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.


Can Fever Blisters Be Spread?

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 your own eyes and genitalia, as well as to other people.

Prevention Tips:

· Avoid mucous membrane contact when a lesion is present

· Do not squeeze, pinch or pick at the blister

· Wash hands carefully before touching your eyes or genital area, or another person

Despite all caution, it is important to remember that it is possible to transmit herpes virus even when no blisters are present.


Treatment consists of coating the lesions with a protective barrier ointment containing an antiviral agent, for example 5% acyclovir® ointment. Also, acyclovir in a pill form (Valtrex®) can be helpful in speeding resolution. Presently, there is no cure, but there is much research activity underway in this field. Contact your doctor or dentist for the latest information. The symptomatic treatments listed below an also be helpful.

What are Canker Sores?

Canker sores (also called aphthous ulcers) are small, shallow ulcers occurring on the tongue, soft palate, or inside the lips and cheeks (mobile mucosa). They are quite painful, and usually last 5-10 days. They are usually not accompanied by a fever.


The best available evidence suggests that canker sores result from an altered local immune response associated with stress, trauma, or local irritants, such as eating acidic foods (i.e., tomatoes, citrus fruits and some nuts.) Other theories include vitamin (B12), Lysine, or mineral (Iron, Zinc) deficiencies.

Can Canker Sores Be Spread?

No, since they are not caused by bacteria or viral agents, they cannot be spread locally or to anyone else.


The 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. Anesthetic creams such as Zilactan B® may also be beneficial. Other treatments include Peridex® or prednisolone mouth rinses. Chloraseptic lozenges® can be temporarily helpful. Magic mouthwash and carafate in saline may also be of benefit. Occasionally we will also cover the patient with a low dose antibiotic elixir—such as amoxil and do nystatin oral rinses to preclude any secondary bacterial or fungal infections. Anecdotal therapies such as L-lysine have been advocated by many of our patients. Any thing patients find helpful is good medicine. Unfortunately, no cure exists at present.

What About Other Sores?

For any mouth lesion that does not heal in two weeks, you should see your specialist. There is an entity we simply refer to as “Burning Mouth Syndrome”. Other names include Glossodynia and Glossopyrosis. The cause is generally idiopathic (meaning we are idiots regarding the pathology, we do not understand the cause). Theories on viral infections, autoimmunities, and or vitamin or mineral deficiencies abound. Typically we can check some blood studies such as a CBC, Serum Iron, Vit B12, Folate, Zinc, ESR, ANA, RF, SSA, and SSB. The offending area can also be biopsied and sent in Michel’s Solution for immunoflourescence studies can prove helpful in eliminating an autoimmune cause. Treatment options include Ace Inhibitors, Topical Capsaicin, TCA’s, Antifungals, Antivirals, Topical Steroids, or Benzodiazepines. These seem complicated but your specialist at Midwest ENT can help you work through it all.

Burning Tongue
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