Stomatitis is a general term for an inflamed and sore mouth that can cause pain and difficulty talking, eating, and sleeping. It can occur anywhere in the mouth, including the inside of the cheeks, gums, tongue, lips, and palate. There are two main types of stomatitis:

• Canker sore: A canker sore, also known as an aphthous ulcer, is a single pale or yellow ulcer with a red outer ring or a cluster of such ulcers in the mouth, usually on the cheeks, tongue, or inside the lip.

• Cold sore: A cold sore, also known as herpes stomatitis, is a viral infection that causes painful blisters on or around the lips.

Stomatitis can be caused by a variety of factors, including infection, irritants, trauma, or allergic reactions. Some cases are idiopathic, meaning the cause is unknown. Treatment for stomatitis depends on the cause and may include topical medications, pain relief, and treating underlying conditions. If stomatitis is recurrent, further tests may be done to identify underlying causes.