Canker sores, medically known as aphthous ulcers, are common, painful lesions that develop inside the mouth. These shallow, non-contagious sores can make everyday activities like eating, drinking, and speaking uncomfortable. While they are generally harmless and resolve on their own, the intense discomfort often prompts people to seek information about their duration. Understanding the typical healing time and influencing factors helps manage the condition effectively.
Identifying Canker Sores
A canker sore appears as a small, round or oval ulcer inside the mouth. The center of the lesion is typically white, gray, or pale yellow, surrounded by a bright red border of inflamed tissue.
These painful sores most often form on the soft, mobile tissues of the mouth, such as the inside of the cheeks, the lips, the tongue, and the soft palate. They can also appear at the base of the gums or directly on the attached gum tissue near the teeth. Canker sores are not contagious and result from internal factors or localized trauma.
It is important to distinguish canker sores from cold sores (fever blisters). Cold sores are caused by the highly contagious herpes simplex virus (HSV-1) and typically appear outside the mouth, on or around the lips. Canker sores are never found on the outer skin of the lips and do not result from a viral infection.
Typical Healing Timeline
The duration of a canker sore depends on its type, but the majority are the minor form. Minor aphthous ulcers account for about 80% of all cases, measuring less than 1 centimeter in diameter and remaining relatively shallow. These common sores generally heal spontaneously within 7 to 14 days and do not leave scarring.
The healing process starts with a day or two of tingling or burning before the sore fully forms. The ulcer enlarges over the next few days before stabilizing and beginning the final healing stage. Sores located on the gums heal at the same speed as those elsewhere in the mouth. However, sores on the gums or hard palate can be especially painful because the tissue is tightly bound to the bone, making it sensitive to friction from speaking or eating.
The less common major aphthous ulcer is larger, often exceeding 1 centimeter, and is much deeper. These severe sores take significantly longer to resolve, with healing times ranging from a few weeks up to six weeks or more. Major ulcers are also more likely to leave behind scar tissue.
Common Triggers and Prevention
While the exact cause of canker sores is unknown, certain factors are linked to their development. Physical trauma is a frequent trigger, often involving an accidental cheek bite, aggressive brushing, or irritation from dental appliances like braces or dentures. This damage creates an entry point for the ulceration process.
Dietary factors also contribute, as acidic or abrasive foods can irritate the mouth lining and provoke a sore. Common culprits include citrus fruits, tomatoes, pineapples, and sharp, crunchy snack foods. Additionally, a deficiency in certain nutrients has been associated with an increased occurrence of canker sores:
- Vitamin B12
- Iron
- Folic acid
- Zinc
Other systemic factors, such as high emotional stress or lack of sleep, can weaken the immune system and make the mouth vulnerable to an outbreak. Hormonal fluctuations, particularly in women, are also known triggers. To reduce the frequency of sores, use a soft-bristled toothbrush and avoid known trigger foods. Managing stress and ensuring a balanced diet rich in the identified vitamins and minerals can also help lower the risk of recurrence.
Accelerating Recovery and When to Seek Help
While most minor canker sores heal naturally, certain home and over-the-counter treatments can reduce pain and support recovery. Rinsing the mouth with a solution of warm water and salt or baking soda can help soothe irritation and maintain a clean environment for healing. Over-the-counter topical gels or pastes containing ingredients like benzocaine or hydrogen peroxide can be applied directly to the sore to temporarily numb the pain.
Maintaining meticulous oral hygiene is important to prevent secondary infection, but brushing must be done gently with a soft brush to avoid further irritation. For persistent or painful cases, a dental professional may recommend a prescription steroid mouth rinse or topical medication to reduce inflammation. In some instances, a dentist may use silver nitrate to cauterize the sore, which provides instant pain relief.
Seek professional medical or dental attention if a canker sore exhibits certain characteristics. Any sore that is unusually large, begins to spread, or lasts longer than two to three weeks should be evaluated by a healthcare provider. Recurrent sores that happen frequently or are accompanied by systemic symptoms may indicate an underlying health issue:
- Fever
- Diarrhea
- Skin rash