Aphthous stomatitis is a common condition characterized by recurrent round or oval painful ulcers, commonly known as canker sores, that appear in the mucous membranes of the mouth, such as the inside of the lips or cheeks, on the gums, in the soft palate, on the floor of the mouth, or on the tongue. In some individuals, recurrent aphthous ulcers may be associated with other serious health concerns.

Symptoms of aphthous stomatitis usually begin with a sensation of burning discomfort one or two days before the ulcers appear (prodrome). The ulcer or ulcers usually first appear(s) as a round, yellow raised spot with a red halo that then develops into a painful ulceration that is attached to the mucosa by a white, yellow, or grey membrane.

There is no cure for aphthous stomatitis, and most minor ulcers heal within one to two weeks without treatment. Treatment for aphthous stomatitis is therefore focused on decreasing pain, improving healing, and preventing recurrences and includes local anesthetics, such as benzocaine; occlusive agents, such as bismuth subsalicylate, sucralfate, and 2-octyl cyanoacrylate; bioadherent emollient pastes; antiseptics, such as chlorhexidine gluconate and hydrogen peroxide; glucocorticosteroids, such as clobetasol, dexamethasone, fluocinonide, and triamcinolone; antimicrobials, such as tetracycline, doxycycline, or minocycline; honey; immunomodulatory drugs, such as amlexanox, colchicine, cyclosporine, cyclophosphamide, dapsone, methotrexate, montelukast, thalidomide, or retinoids; pentoxifylline; or quercetin. Other treatments may include the use of herbal remedies, tincture of benzoin, cautery with silver nitrate, laser therapy, and supplementation with iron, zinc, and vitamins B1, B2, B6, B12, or C.