Canker Sore (Aphthous Ulcer):
A parent's guide to condition and treatment information

Canker sores (aphthous ulcers), or aphthae, are the most common cause of periodic (recurring) ulcers of the oral and genital linings (mucous membrane surfaces). Their cause is unknown, but stress, lack of sleep, mechanical injury (trauma), and perhaps some vitamin deficiencies, toothpastes, and foods can make the condition worse. Some people with anemia and other medical conditions that weaken the immune system may be more likely to develop canker sores.  

There are 3 types of canker sore:

• Minor aphthae (80% of cases)
• Major aphthae (Sutton disease, approximately 10% of cases)
• Herpetiform aphthae (10% of cases)

Minor aphthae heal within 1–2 weeks.

Major aphthae are extremely painful, last from 2–4 weeks, and generally cause scars after they heal.

Herpetiform aphthae progress in a way that is similar to minor aphthous ulcers.