An aphthous ulcer, commonly known as a canker sore, is a small, painful, grey-white or yellow sore that often appears inside the mouth. It usually forms on the inner cheek, tongue, inner lip or gums. The exact cause is not fully understood, but factors thought to play a role include stress, a weakened immune system, hormonal changes, certain vitamin deficiencies, trauma (such as dental treatment or biting the cheek) and some food allergies.
Canker sores usually heal on their own within 1–2 weeks, but antiseptic mouthwash and topical creams may be recommended to relieve pain and speed healing. For frequently recurring aphthous lesions, suppressive treatments can be used.
If aphthous-like sores also appear in the genital area, this may be a sign of another condition. In particular, Behçet's disease is a chronic inflammatory disease characterised by recurring ulcers in the genital area and mouth. Sores in the mouth or genital area can also be a sign of sexually transmitted infections. When such symptoms occur, it is important to see a doctor for the correct diagnosis and treatment.