A canker sore, medically known as an aphthous ulcer, is a small, shallow lesion that forms on the soft tissues inside the mouth. These painful ulcers typically appear on the cheeks, lips, tongue, or at the base of the gums. They present as a white or yellowish center surrounded by a bright red border, making eating and talking uncomfortable. Unlike cold sores, which are caused by the herpes virus, canker sores are not contagious.
Types of Canker Sores and Pain Duration
The intensity and duration of pain depend largely on the sore’s type. Minor aphthous ulcers are the most common form, accounting for about 80% of cases, and are typically small, under 1 centimeter in diameter. Pain from a minor sore is most intense during the first three to four days after the ulcer forms. Discomfort generally begins to subside significantly after the first week, even if the sore has not completely disappeared.
Major aphthous ulcers are less frequent, but they are larger and deeper, often exceeding 1 centimeter across. These larger lesions cause more severe pain that lasts for an extended period. The intense pain may continue for several weeks, making daily activities like chewing and speaking difficult. Herpetiform ulcers are the third, rarest type, presenting as clusters of tiny sores that may merge into one larger ulcer. Their pain duration mirrors that of minor sores, lasting about seven to ten days.
Total Healing Timeline
The total time required for a canker sore to heal completely is distinct from the pain timeline. For the common minor aphthous ulcer, the entire healing process takes between seven and fourteen days. Healing involves the full regeneration of the epithelial tissue that forms the lining of the mouth. The pain usually stops before this full tissue repair is finalized.
Major canker sores require a significantly longer recovery period due to their depth and size. These ulcers can take up to six weeks to achieve complete resolution. Because they penetrate deeper into the oral mucosa, major sores may heal with scarring. Scarring is not a typical outcome for the shallower minor sores. The herpetiform type usually heals within one to two weeks without leaving any scar tissue.
Immediate Relief and Home Remedies
Immediate management focuses on reducing pain and irritation to allow for comfortable eating and speaking. Over-the-counter topical anesthetics, such as those containing benzocaine, can be applied directly to the lesion to temporarily numb the nerve endings. Applying a small amount of milk of magnesia onto the sore a few times a day can also help by coating the ulcer and neutralizing irritating acids.
Simple home rinses offer practical relief by altering the oral environment. A warm salt water rinse, made by dissolving a teaspoon of salt in a half-cup of water, helps draw out fluid and create a hostile environment for bacteria. Similarly, a baking soda rinse, created by mixing a teaspoon of baking soda into warm water, may help balance the pH and reduce inflammation. To prevent further irritation, avoid abrasive, acidic, or spicy foods, such as citrus fruits, tomatoes, and chips, which can worsen the pain and slow healing.
When Professional Medical Advice is Necessary
While most canker sores resolve on their own, certain signs warrant consultation with a healthcare professional. A sore that persists for three weeks or longer should be evaluated, as this extended duration can indicate a different underlying condition. Unusually large or deep ulcers, characteristic of major aphthous stomatitis, may require prescription-strength treatments to manage pain and accelerate healing.
Recurrent episodes where new sores develop before old ones have healed also suggest a need for medical investigation. If the pain is so severe that it prevents normal eating or drinking, or if the sore extends onto the lips past the vermilion border, a doctor or dentist should be consulted. These symptoms can sometimes be associated with nutritional deficiencies, immune system issues, or other systemic diseases that require specific medical intervention.