They just run their course. Canker sores are open sores on the tongue, gums, or inside the cheeks. They are painful and irritating. Canker sores usually heal in 7 to 10 days. Stress, biting your tongue or cheek, heredity, female hormones, and food allergies are all possible causes of canker sores.
Small blisters form, break, and ooze a clear fluid.
A scab forms then sloughs off to uncover pink, healing skin. The contagious herpes simplex virus type 1 causes cold sores. The virus is passed between people in saliva or by using contaminated eating utensils, towels, and shaving tools such as razors. The sores last about a week or two and often recur in the same spot again and again. The virus lies dormant until triggered by colds, fever, fatigue, sunlight, stress, or menstruation.