What is the white stuff in a canker sore?

The white stuff in a canker sore is called an ulcer, which is a shallow, crater-like area that manifests inside the mouth. The ulcer is composed of dead skin cells, blood cells, and debris from the damaged tissues. It is typically white or yellow in color and can be painful or uncomfortable to the touch. The ulcer is not contagious but can be triggered by various factors such as stress, injury from brushing, and certain foods. It usually heals in 1-2 weeks without the need for treatment, but over-the-counter medications such as gels or mouth rinses can help alleviate the symptoms. In rare cases, a canker sore can be a sign of a more severe underlying condition, and a consultation with a healthcare provider may be necessary.