Possible causes of canker sores

While the cause of canker sores is unknown, a number of observations and/or scientific studies point to the following factors being causally involved.

Damage (physical and/or chemical trauma) to the mucous membrane from varying sources

Damage from physical trauma to the buccal mucosa

  • accidentally biting one's oral mucosa
  • wearing dental braces or a denture
  • tooth extraction
  • radiation "therapy" to the mouth causing inflammation of the mucous lining

Damage from chemical trauma to the buccal mucosa

  • sodium lauryl sulphate, SLS, aka sodium dodecyl sulphate or SDS, a synthetic detergent compound found in most toothpastes including some "natural" ones as well as some conventional mouthwashes

    Several scientific studies (see e.g. www.ncbi.nlm.nih.gov/pubmed/7825393) done by the Department of Oral Surgery and Oral Medicine at Oslo University's Dental Faculty (Prof Pal Barkvoll, B.B. Herlofson) showed a strong link between SLS-containing toothpaste and the frequency of recurrent aphthous ulcers. The studies among other things concluded that an SLS-free toothpaste may be recommended for individuals presenting recurrent aphthous ulcers.

    One study (see www.ncbi.nlm.nih.gov/pubmed/8811135) even compared the effect of using one of two different toothpaste detergents (sodium lauryl sulfate [SLS] and cocamidopropyl betaine [CAPB]) or a detergent-free toothpaste on 30 recurrent aphthous ulcers patients.

    Result: a significantly increased frequency of aphthous ulcers was found in those who had brushed with an SLS- containing paste than in those brushing with a CAPB-containing one or the placebo paste free of detergents.[2]
  • medication such as certain lozenges against sore throat which upset the oral flora
  • artificial dyes in medications and supplements
  • artificial food additives, eg preservatives, such as benzoic acid (E210)
  • acidic foods and drinks (tomato products, raw tomatoes, lemon juice), anything with citric acid in it (such as soda etc.)
  • tobacco chewing

Systemic causes of canker sores

  • nutritional (vitamin/mineral) deficiencies, particularly of iron, zinc, and folate/folic acid as well as vitamin B12,
  • intestinal auto-intoxication: constipation, build-up of toxins in the body from inability to eliminate / toxin overload
  • gluten sensitivity / intolerance / Celiac disease (inability to process glutens from wheat/barley and other cereals)
  • food allergies (eg nuts, almonds, hard cheeses, milk etc.)
  • taking NSAID medication, antibiotics, Vitamin K antagonists, Meprobamate
  • stress
  • fever
  • cancers such as leukemia and lymphoma
  • cytotoxic chemotherapy causing stomatitis of the mucous linings
  • mycoses (fungal infections)

Generally, natural hygienists and similar naturopathic schools consider outbreaks of the skin to denote both a weakness of the immune system and a cleansing reaction, with some opportunistic microorganisms "taking advantage" of the situation.

Presumably in extremely rare cases only, a persistent canker sore could be a tumor.

Natural Canker Sore Remedies and Cures

Avoiding the above-listed damages from physical/chemical trauma and systemic causes to the extent possible of course would seem like your first line of defense. Following is a series of other approaches which were found helpful by various individuals.


Oil pulling

The book "Die Heilkunst von Morgen" by Erika Herbst reports that canker sores are regularly healed with either oil pulling or water pulling and specifically cites the case of a man who had continuously suffered from canker sores but who received immediate relief after starting to practice oil pulling.

Water drinking

Drinking proper amounts of clean water is really a basic measure to take in most any affliction.

Salt water

A man who had suffered with painful canker sores for months (to the point of the doctor advising surgery) started to use warm salt water rinses several times daily. It took under a month for all the sores to disappear. Apparently the same approach is also successful with a sore tongue.

In a similar vein, another person reported that since brushing her teeth near-exclusively with Himalayan salt and rinsing with a Himalayan salt solution (the latter in the case of - meanwhile rarely occurring - gum infection), her gums felt fine and canker sores had hardly ever recurred.

If you can stand the momentary pain, you can also directly dab salt on; it will sting but this sensation is likely to subside and the sore to eventually heal.

A similar effect as with warm salt water can be obtained with baking soda[4] dissolved in water and even with a very weak hydrogen peroxide[5] solution. Make sure to hold the solution in your mouth for a minute, it will help to clean the tissues around the ulcer which will assist its healing and reduce pain.

Urine therapy

Three cases of successfully overcoming canker sores thanks to uropathy are reported in a (German-language) book by Carmen Thomas, a well-known German author of books on urine treatment and other "taboo" subjects. Another case is mentioned in Dr. Thakkar's book "Wonders of Uropathy". Compare Urine therapy for the healing of teeth and gums.

Herbal Remedies

Aloe vera

A healing and soothing herb one can dab on mouth sores which will simultaneously benefit one's teeth and gums.[3]

Agrimonia eupatoria

An astringent herb used as a mouthwash for oral infections

Australian tea tree oil

is anti-inflammatory. Apply one drop of tea tree oil mixed with two drops of hazelnut oil directly on the canker sores, three times a day.

More about Tea tree oil.

Black tea

contains astringent tannins. Soak a piece of cotton or gauze in the cold tea and apply for several minutes until the discomfort subsides. As with abscesses, one can also apply a wet tea bag directly to the sore.

Camomile rinses

An old standby, camomile is well known for its soothing qualities.

Carrot greens

Drinking a decoction made of carrot greens (one handful of greens in two cups of water) is a (French) home remedy for healing canker sores. Use the greens from organic carrots to avoid the dose of pesticides that comes with conventional carrots.


Before mealtimes, cut a clove, apply to sores and let sit for a while.

Grapefruit seed extract

Additionally helped with bleeding gums.

Horsetail (Equisetum arvense) tea

An important healing herb according to several herbalists including famed Austrian Maria Treben, horsetail is also recommended for stomatitis and inflammation of the oral mucosa. To make a horsetail rinse, pour 1/4 litre of boiling water (approx. 8.454 fluid ounces) over 1 heaped teaspoon of horsetail. Use as a mouth rinse / gargle after cooling.

Lemon juice / apple cider vinegar

While some seem to get mouth sores from lemon juice, some bravehearts seem to have benefitted from directly dabbing on these very acidic substances.

Lemon balm (Melissa officinalis) extract

is anti-inflammatory.

Licorice root (Glycyrrhiza glabra)

While licorice apparently is very helpful for teeth and gums, it has also been found useful for mouth sores.

Propolis tincture (alcoholic extract)

Propolis is a "multi-purpose" anti-inflammatory and antimicrobial bee product (see background on propolis) which is sold as a tincture, as drops and even as a mouth spray. Simply dab on or rinse with it.

Sage tea (Salvia)

Use as mouth rinse.

Swedish Bitters

A powerful herbal tincture, Swedish Bitters have also been found effective with canker sores (frequently moisten with the drops "and healing soon occurs" - reportedly also works with toothache, gum problems and a host of other conditions).[1]


Vitamins, multivitamins, supplements

  • folate/folic acid, Vitamin B12, high-dose acidophilus and acidophilus mouth rinses.
  • at the first tingling sensation, apply vitamin E from a capsule, to accelerate healing take three times 500mg of vitamin C with bioflavonoids a day for three days


Rinse your mouth with sauerkraut juice several times a day or place some sauerkraut against the affected area(s) for a while. Chew and swallow. Since it is likely that the active ingredient is the lactic acid contained in the sauerkraut, other lactic-acid-fermented foods should also work, incl. kombucha.

Stay away from "offenders"

If you know which items trigger canker sores in your mouth (eg acidic or spicy items, coffee, alcohol, dairy, sugar, nuts...), try avoiding them for a while while using some of the suggestions on this page. If it is acidic foods for you, you could also try neutralizing their effect by immediately rinsing your mouth with a baking soda solution or dabbing some straight baking soda on [4].


Xylitol rinses

See Does xylitol help with canker sores (aphthous ulcers) and similar things?.

Milk rinses

Rinse your mouth with milk before meals if it is too painful to eat. Milk coats the ulcer and allows you to eat.


In his landmark book "Earthing the most important health discovery ever", Clint Ober reports that he used to have multiple severe allergies including getting canker sores after eating oranges.

All of his sensitivities vanished when he started regularly grounding himself - a good illustration for how providing the body with its most essential needs (which include basics such as proper hydration, natural full-spectrum light and contact with the earth) can erase many intractable conditions for good.[6]


A pure white mineral oil plus essential oils, see ballistol-shop.de .

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1 Background on this herbal remedy eg at Swedish Bitters Healing Testimonials: A Powerful Herbal Remedy?.

2 More regarding the side effects of sodium lauryl sulfate under Toothpaste: hazardous to dental and bodily health?.

3 For the scientific reasons why aloe can effectively help teeth, gums and canker sores, compare Aloe studies as well as Whole-leaf aloe in dentistry and oral applications: a powerful medicinal plant helping against tooth decay, gingivitis, periodontitis, and more.

4 More on baking soda's benefits in tooth and gum care.

5 Be aware that hydrogen peroxide can be a double-edged sword, see e.g. this important warning.

6 Read Healing Cancer Naturally’s “Greatest Hits" for a summary of six truly foundational habits to adopt to further ANY kind of healing.

All remedies