The natural history, complications and prognosis of recurrent aphthous ulcers varies with disease severity.

• The most common form, the minor, is characterized by ovoid or circular lesions, smaller than 1cm in diameter, in number that varies from 1 to 5, covered by a thin pseudomembrane of white-gray color. It spontaneously resolves after 10-14 days leaving no scar.
• The major form is less common, present with ulcers larger than 1cm in diameter, being deeper and associated with dysphagia. It can last for several weeks and may leave scars. They often affect the lip, tongue and soft palate.
• The herpetiform form is rarer and presents with pinpoint ulcers that are small in size (0.1-0.2cm) that may be present in large numbers or coalesce forming large lesions. These lesions may take 7-14 days to resolve usually leaving a scar. It is not related to the HSV.^[1]

• Complications are rare, and mostly due to associated diseases than the ulcers. The more severe forms of the disease may cause scarring.

• Aphthous ulcers usually heal on their own. The pain usually decreases in a few days. Other symptoms disappear in 10 to 14 days.
• Prognosis of the associated medical conditions is highly variable and should be assessed individually.