It might surprise you to learn that there are many different mouth sores that can appear and behave very much like canker sores. It is important to know a little about these other mouth sores so that you can distinguish them from canker sores. One important reason to make a proper distinction is that canker sore treatment is different than the treatment of other mouth sores. Moreover, unlike canker sores, certain “canker sore mimickers” can be contagious. We discuss some of the mouth sores that are most closely related to canker sores and provide keys to help tell them apart.
Cold sores and canker sores
The two most often confused mouth sores are cold sores and canker sores in mouth. Both types of mouth sores can flare up periodically and both are brought on by stress and illness. Cold sores are small, painful lesions that are usually found only on and around the lip. While canker sores can occur on the lip, they can appear on just about every interior surface of the mouth, too. Canker sores are not contagious; however since cold sores are caused by a herpesvirus, they can be spread from one person to another. The fact that cold sores are contagious and canker sores are not can dictate patient behavior. For example, if you have a cold sore, you can properly protect against spreading it to loved ones. On the other hand, close contacts can be relieved knowing that if the lesion is a canker sore that they will not contract it from you.
Oral lichen planus
Oral lichen planus is also commonly confused with canker sores because both diseases can cause ulcerations in the mouth that are covered by a white plaque. Both cause mouth sores on the gums, tongue, and inside of the cheeks. Canker sores are often more painful than lichen planus lesions, but this is not a hard and fast rule. One feature that may help tell the difference is that lichen planus can occur in various places in the body including the scalp, fingernails, eyes, and genitals. Also, lichen planus lesions are not simply ulcers (though they can be), but can be bumps and blisters of red or white.
Thrush (oral fungal infection)
One way to distinguish the cottony white lesions of oral thrush from canker sores is by the amount of pain that they cause. For the most part, oral thrush is relatively painless (though it can be painful in severe cases). Oral candidiasis or fungal infection of the mouth can even interfere with swallowing in severe cases, just like in the case of severe canker sores. The best way to distinguish between the two entities is to look at the depth of the mouth sore. If the white coating appears stuck on and scratching it causes the lesion to bleed, it is likely thrush. Canker sores, on the other hand, create depressions in the sink (ulcers) that usually look more darkly red than normal oral tissues.
Other diseases that mimic cankers sores
The above list only includes a few of the most common canker sore mimickers. In truth there are dozens of possible diseases that can be confused with canker sores. A select list is included here:
- Arthritis, Conjunctivitis, Urethritis Syndrome
- Behcet Disease
- Cancers of the Oral Mucosa
- Celiac disease
- Contact Stomatitis
- Crohn’s Disease
- Cyclic neutropenia – Recurrent infections
- Erythema Multiforme
- Food allergy/hypersensitivity
- Hand-Foot-and-Mouth Disease
- Histoplasmosis
- Human Immunodeficiency Virus Infection
- Mouth and genital ulcers with inflamed cartilage (MAGIC) syndrome
- Necrotizing ulcerative gingivostomatitis (Vincent stomatitis, trench mouth) -
- Pemphigus Vulgaris
- Periodic fever, aphthous pharyngitis, and adenopathy (PFAPA) syndrome
- Reactive Arthritis
- Sprue
- Sutton disease (periadenitis mucosa necrotica recurrens)
- Sweet syndrome – Triad of neutropenia, fever, and rash
- Syphilis
- Systemic Lupus Erythematosus
- Thiamine deficiency
- Varicella Zoster
If you are not sure that you have canker sores or some other mouth lesion, and find out more about canker sore diagnosis and consult your physician.
References
Gonsalves WC, Chi AC, Neville BW. Common oral lesions: Part I. Superficial mucosal lesions. Am Fam Physician 2007;75:501-507.
Scully C, Gorsky M, Lozada-Nur F. The diagnosis and management of recurrent aphthous stomatitis: a consensus approach. J Am Dent Assoc 2003;134:200-207.
