An ulcer is a defect on the mucosa where the lining has been disrupted followed by the formation of inflammatory necrotic tissue. Ulcers will usually last for about 10 days and ulcer-free periods will depend on the frequency of attacks. RAS is common, but the presentation in individuals varies. Ulcers will usually last for about 10 days and ulcer-free periods will depend on the frequency of attacks.
Some individuals experience only one ulcer occasionally, while others have continuous ulcers.
The condition is most frequent in young adults although it does occur in children. Mouth ulcers due to herpes virus can occur as a primary infection or a secondary recurrent infection. Most of the population has been exposed to herpes virus and do not experience a primary infection. When a primary infection manifests it is characterized by multiple small vesicles or blisters that quickly break and appear as yellowish ulcers. These join together to form larger irregular painful ulcers.