Canker sores (aphthous ulcers) are small, shallow lesions that develop on the soft tissues inside the mouth, including the inner cheeks, tongue, or gums. A typical sore is a round or oval ulcer with a white or yellowish center surrounded by a bright red, inflamed border. While painful and non-contagious, most canker sores on the gums resolve on their own, generally healing completely within one to two weeks.
The Typical Duration and Healing Timeline
The healing process for the most common type of canker sore, the minor aphthous ulcer, follows a predictable timeline. The initial stage is a prodromal phase, where a tingling or burning sensation is felt one to three days before any visible sore appears. The ulcer then fully forms, typically reaching its peak size and discomfort level within the first three to six days.
This is when the shallow lesion is most noticeable and painful, often making eating and speaking difficult. As the healing phase begins, the pain gradually subsides. The ulcer’s center transitions from white or yellow to a grayish color before the tissue regenerates. Minor sores typically heal completely within 7 to 14 days without leaving behind any scar tissue.
Factors Influencing How Long Canker Sores Last
The duration is significantly influenced by the specific type of canker sore. Minor aphthous ulcers, accounting for about 80% of cases, are usually less than 1 centimeter in diameter and adhere to the two-week healing window. Major aphthous ulcers are larger, often exceeding 1 centimeter, deeper, and more painful. These severe sores can persist for two to six weeks, or longer, and may result in scarring upon resolution.
External factors and underlying triggers also contribute to a longer presence of the ulcer. Minor trauma, such as an accidental bite, vigorous toothbrushing, or irritation from a dental appliance, can initiate a sore and disrupt healing. Nutritional deficiencies, particularly low levels of Vitamin B12, iron, or folic acid, are associated with recurrent episodes and may impede recovery. Stress and sensitivities to acidic or spicy foods can also aggravate an existing sore, prolonging its duration.
Accelerating Healing and Managing Discomfort
While most canker sores heal naturally, several actions can accelerate the process and alleviate pain. Applying over-the-counter topical anesthetics, often containing benzocaine, directly to the sore provides immediate but temporary pain relief by numbing nerve endings. Protective gels or pastes can also form a physical barrier over the ulcer, shielding it from irritation caused by food or saliva.
Simple home remedies can help maintain oral hygiene and soothe the inflamed tissue. Rinsing the mouth several times a day with warm salt water or a baking soda solution helps clean the area and neutralize the acidic environment. Applying a small amount of milk of magnesia with a cotton swab creates a protective coating and reduces irritation. Applying natural substances like honey or aloe vera gel can also provide a soothing effect and aid regeneration.
Preventative measures are important to avoid further damage that could extend healing time. Use a soft-bristled toothbrush and a toothpaste that does not contain the foaming agent sodium lauryl sulfate, which can irritate the oral mucosa. Avoiding abrasive, spicy, or highly acidic foods, such as citrus fruits or tomatoes, minimizes pain and prevents additional tissue trauma during an outbreak. For severe cases, a doctor or dentist may prescribe medicated mouth rinses containing steroids or lidocaine to reduce inflammation and pain.
When to Seek Professional Medical Advice
While the majority of canker sores are self-limiting, certain signs indicate the need for a professional evaluation from a dentist or physician. Seek medical attention if a sore persists for longer than two weeks without showing any signs of improvement or healing. Sores that are unusually large, deep, or cause pain severe enough to interfere with eating or drinking may require prescription treatments.
Recurrent outbreaks, where new sores appear before old ones have healed, or frequent episodes occurring several times a year, should be discussed with a healthcare provider. Consult a doctor immediately if the canker sore is accompanied by systemic symptoms, such as a high fever, diarrhea, skin rash, or general discomfort. These signs could suggest an underlying health condition that requires specific medical management beyond topical treatments.