Canker sores are small ulcerations within the mouth.
Doctors call this common condition aphthous stomatitis.
What are the symptoms of canker sores?
Canker sores appear alone or in clusters as shallow, painful erosions in the mucous membrane inside the mouth. They typically have slightly raised, yellowish borders surrounded by a red zone, and are sometimes covered with a yellowish opaque material. Fatigue, fever, and swollen lymph nodes may be present in severe attacks.
Dietary changes that may be helpful for canker sores
Sensitivity to gluten, a protein found in wheat and other grains, has been associated with recurrent canker sores in some people. In preliminary trials, avoidance of gluten has reduced recurrent canker sores in people whether or not they had celiac disease,1 2 3 but a double-blind trial did not find gluten avoidance helpful to people with recurrent canker sores who did not have celiac disease.4 One preliminary trial suggested that people with recurrent canker sores, whose blood contains antibodies to gliadin (a component of gluten), may respond to a gluten-free diet even if they have no evidence of the tissue changes associated with celiac disease.5
Other food sensitivities or allergies may also make canker sores worse.6 7 One preliminary trial found evidence of food allergy in half of a group of people with recurrent canker sores; avoidance of the offending foods resulted in improvement in almost all cases.8 While a double-blind study concluded that typical allergy mechanisms play only a minor role,9 people with recurrent canker sores should discuss the diagnosis and treatment of food sensitivities with a doctor. For some people, treating allergies may be a key component to restoring health.
Lifestyle changes that may be helpful for canker sores
Minor trauma from poor-fitting dentures, rough fillings, or braces can aggravate canker sores and should be remedied by a dentist.
Several reports have found sodium lauryl sulfate (SLS), a component of some toothpastes, to be a potential cause of canker sores.10 In one trial, most recurrent canker sores were eliminated just by avoiding toothpaste containing SLS for three months.11 Positive effects of eliminating SLS have been confirmed in double-blind research.12 SLS is thought to increase the risk of canker sores by removing a protective coating (mucin) in the mouth. People with recurrent canker sores should use an SLS-free toothpaste for several months to see if such a change helps.
Measurements of stress were associated with recurrent canker sores in one preliminary study,13 but not in another.14 More research is needed to determine whether stress reduction techniques might reduce canker sore recurrences.
Nutritional supplements that may be helpful for canker sores
Several preliminary studies,15 16 17 18 though not all,19 have found a surprisingly high incidence of iron and B vitamin deficiency among people with recurrent canker sores. Treating these deficiencies has been reported in preliminary20 21 and controlled22 studies to reduce or eliminate recurrences in most cases. Supplementing daily with B vitamins—300 mg vitamin B1, 20 mg vitamin B2, and 150 mg vitamin B6—has been reported to provide some people with relief.23 Thiamine (B1) deficiency specifically has been linked to an increased risk of canker sores.24 The right supplemental level of iron requires diagnosis of an iron deficiency by a healthcare professional using lab tests.
Zinc deficiency has also been linked with recurrent canker sores in preliminary studies25 and in one case report.26 A preliminary trial found that supplementation with up to 150 mg of zinc per day reduced recurrences of canker sores by 50 to 100%; participants who were zinc deficient experienced the most consistent benefit.27 However, a double-blind trial (that did not test people for zinc deficiency) did not find zinc supplements helpful for recurrent canker sores.28
According to preliminary reports, some people with recurrent canker sores may respond to topical and/or oral use of Lactobacillus acidophilus29 and Lactobacillus bulgaricus.30 However, a double-blind study found no effect of acidophilus bacteria on the healing time of canker sores.31
Are there any side effects or interactions with canker sores?
Refer to the individual supplement for information about any side effects or interactions.
Herbs that may be helpful for canker sores
Licorice that has had the glycyrrhizic acid removed is called deglycyrrhizinated licorice (DGL). Glycyrrhizic acid is the portion of licorice root that can increase blood pressure and cause water retention in some people. The wound-healing and soothing components of the root remain in DGL.
A mixture of DGL and warm water applied to the inside of the mouth may shorten the healing time for canker sores, according to a double-blind trial.32 This DGL mixture is made by combining 200 mg of powdered DGL and 200 ml of warm water. It can then be swished in the mouth for two to three minutes, then spit out. This procedure may be repeated each morning and evening for one week. Chewable DGL tablets may be an acceptable substitute.
A gel containing the aloe polysaccharide acemannon was found in one double-blind trial to speed the healing of canker sores better than the conventional treatment Orabase Plain®.33 The gel was applied four times daily. Because acemannon levels can vary widely in commercial aloe gel products, it is difficult to translate these results to the use of aloe gel for canker sores.
The antiviral, immune-enhancing, and wound-healing properties of echinacea may make this herb a reasonable choice for canker sores. Liquid echinacea in the amount of 4 ml can be swished in the mouth for two to three minutes, then swallowed. This procedure may be repeated three times per day. However, no research has investigated the possible effects of this treatment.
Because of its soothing effect on mucous membranes (including the lining of the mouth) and its healing properties, chamomile may be tried for canker sores and other mouth irritations.34 A strong tea made from chamomile tincture can be swished in the mouth before swallowing, three to four times per day. Goldenseal has also been used historically as a mouthwash to help heal canker sores.
Myrrh, another traditional remedy with wound-healing properties, has a long history of use for mouth and gum irritations. Some herbalists suggest mixing 200 to 300 mg of herbal extract or 4 ml of myrrh tincture with warm water and swishing it in the mouth before swallowing; this can be done two to three times per day.
Historically, herbs known as astringents have been used to soothe the pain of canker sores. These herbs usually contain tannins that can bind up fluids and possibly relieve inflammation. They are used as a mouth rinse and then are spit out. None of these herbs has been studied in modern times. Examples of astringent herbs include agrimony, cranesbill, tormentil, oak, periwinkle, and witch hazel. Witch hazel is approved by the German Commission E for local inflammations of the mouth, presumably a condition that includes canker sores.
Are there any side effects or interactions with canker sores?
Refer to the individual herb for information about any side effects or interactions.