Aphthous ulcers are canker sores. These small round or oval ulcers can develop on the mucous membranes of the mouth or genitals. They usually form on the soft pinkish-red tissue inside the mouth that is not directly attached to bone. For example, they can form inside the lips and cheeks and underneath the tongue. They do not usually form on the roof of the mouth (hard palate) or on the gums.
While aphthous ulcers are not life-threatening, they can be very painful. The pain can last up to 10 days and the ulcer usually heals within one to three weeks. Large aphthous ulcers, measuring greater than 1 centimeter in diameter, can take longer to heal.
Aphthous ulcers are not an AIDS-defining illness. In other words, if you have HIV and experience an aphthous ulcer, this does not mean that you have AIDS. However, aphthous ulcers are more common in HIV-positive people and are more likely to recur in HIV-positive people. Aphthous ulcers are also commonly present in other medical conditions, including Crohn's disease and inflammatory bowel disease (IBD).
Even though aphthous ulcers are very common among HIV-positive and HIV-negative people, it's still not clear why they happen. It's likely that hyperactivity of the immune system has something to do with aphthous ulcers, but it's not known how this happens.
People with a history of aphthous ulcers in their family are more likely to get aphthous ulcers. Aphthous ulcers can also be caused by emotional stress and lack of sleep. If you bite the inside of your cheek, this can also result in an aphthous ulcer. People with nutritional problems, such as vitamin B, iron, and folic acid deficiency, are also more likely to develop aphthous ulcers. Some women report aphthous ulcers at certain times in their menstrual cycles. Aphthous ulcers are also a side effect of Hivid® (ddC), an anti-HIV medication.