How do I get rid of a canker sore on my tongue?

Canker sores, also called aphthous ulcers, are the most common kind of mouth ulcer. Cleveland Clinic describes them as small round ulcers that are white, gray or yellow with a red border, and lists the tongue, the underside of the tongue, the inside of the lips and cheeks, and the base of the gums as typical sites. Many people feel burning or tingling a day before the sore appears.

They hurt more than their size suggests, because the tongue moves constantly and rubs the sore against your teeth with every word and bite. Salty, spicy and acidic foods sting. They are not contagious, so you cannot catch one from kissing or sharing a drink.

Figures from a 2022 review in American Family Physician. Despite the name, herpetiform sores are not caused by the herpes virus; they just look like herpes clusters.

Doctors do not know the exact cause. The same review reports that about 20% of the general population gets them, with a peak between ages 10 and 20, and notes that 40% of people who get them have a family history. Cleveland Clinic says it is unusual to get a first canker sore after age 40.

Common triggers include:

• Biting your tongue or rubbing it on a sharp tooth, brace or denture
• Acidic or spicy food, and for some people caffeine, eggs, cheese, peanuts or almonds
• Stress and lack of sleep
• Hormone changes around periods
• Toothpaste containing sodium lauryl sulfate (SLS)
• Some medicines, including NSAIDs and beta-blockers
• Low levels of iron, vitamin B12, folate, zinc or vitamin D

Frequent or severe sores can occasionally be a sign of conditions such as celiac disease, inflammatory bowel disease or a weakened immune system, which is why repeat sores are worth mentioning to a doctor.

The AAFP points out that a cancerous ulcer tends to have a rough surface and lacks the red halo of a canker sore. Several ulcers at once, with a rash on the hands and feet, suggests hand, foot and mouth disease, and the NHS notes several ulcers can also go with oral lichen planus, Crohn's disease or celiac disease.

• Salt water rinse. The NHS suggests half a teaspoon of salt dissolved in a glass of warm water, rinsed and spat out, as often as you like.
• Pharmacy products. A pharmacist can suggest numbing gels or sprays (such as benzocaine products), antimicrobial mouthwash, or corticosteroid lozenges. Follow the label.
• Eat soft, cool food and drink cool drinks through a straw.
• Avoid very spicy, salty or acidic food, crunchy food such as chips and toast, and hot or acidic drinks such as fruit juice.
• Switch to an SLS-free toothpaste if you get sores often.
• Use a soft toothbrush and keep a tongue scraper well away from the ulcer. Clean the rest of the tongue gently, or pause until it heals.

The NHS is honest about the limits: mouth ulcers need time, and there is no quick fix.

For large, very painful or frequent sores, a clinician may prescribe stronger corticosteroid gels, rinses or tablets, or a prescription mouthwash. The 2022 AFP review notes that topical corticosteroids are the main treatment but good-quality evidence for any one product is limited. If sores keep returning, blood tests for iron, B12, folate and other deficiencies, or for celiac disease, may be suggested.

Cleveland Clinic advises calling a provider if a canker sore lasts longer than two weeks, is bigger than a pea, comes with flu-like symptoms, returns two or three times a year, or stops you eating and drinking. The NHS recommends seeing a dentist or GP for any mouth ulcer lasting longer than three weeks, because a long-lasting ulcer is sometimes a sign of mouth cancer.