Self-Help Tips From Dr Sarah Brewer

Aphthous Ulcers – Canker Sores And How To Treat Them

Mouth ulcers, also known as canker sores or aphthous ulcers, affect as many as one in five people on a regular basis. Women are more susceptible to canker sores in the mouth than men, especially during the second half of the menstrual cycle and the onset of menstruation. This suggests that hormone factors are involved in triggering aphthous ulcers, although these influences are not well understood. Around 40% of people have a family history of aphthous ulcers, but the remaining 60% do not, so heredity is not always a factor. Where canker sores and mouth ulcers do run in a family they tend to be more severe.

Aphthous ulcers or canker sores

Most mouth ulcers have no obvious cause, and are known as aphthous ulcers, or canker sores. They are similar to the trauma (or worry) sores that develop on the tip of your tongue when you keep using it to explore a sharp piece of tooth, or due to the friction of wearing braces. In the case of aphthous mouth ulcers, however, there is no obvious cause of irritation.

Aphthous ulcers can appear singly or in a group, typically appearing behind the lower lip, under the tongue or on the inside of the cheek. They are usually oval in shape, with a white or grey centre and an inflamed, red surround. Despite their relatively small size, they are extremely painful – especially when you eat acid or salty foods, as they leave raw nerve endings exposed within the mouth.

So called minor aphthous ulcers, which account for more than 80% of outbreaks, cause 2 to 8 crops of sores a year, each of which lasts for 7 to 14 days and heal without scarring.

Major aphthous ulcer disease (around 10% of outbreaks) is associated with a fewer number of larger ulcers – typically 1 or 2 – which cause severe pain, last for 6 weeks or more at a time, and can heal to leave a scar.

So-called herpetiform aphthous ulcers resemble Herpes simplex sores but are not associated with cold sore viruses. These appear as multiple pinhead sized lesions (sometimes as many as 100) that can merge to form irregular shaped sores. Accounting for 5% to 10 % of cases, these are incredibly painful and make life a misery. These may be linked with gluten sensitivity, and it’s worth following a gluten-free diet for a few weeks to see if this solves the problem.

I will cover treatments for cold sores due to Herpes simplex viruses in a separate post.

The exact cause of aphthous mouth ulcers remains unknown. They are most likely to appear during times of stress, when immunity is naturally reduced.

Do mouth bacteria cause canker sores in the mouth?

Recurrent aphthous ulcers have been linked with over-sensitivity to common mouth bacteria, such as alpha-haemolytic streptococci. Some researchers have suggested these bacteria may breach defences when immunity is low and trigger a cell-mediated immune attack that damages the surrounding mouth lining cells.

Another possibility is that antibodies targeted against these bacteria may cross-react with the mouth lining to cause ulceration. There is no consistent evidence for any of these theories, however, and they remain controversial.

Do food intolerances cause mouth ulcers?

Food intolerances are implicated in the development of some mouth ulcers. If I eat a particular brand of Greek style honey yogurt, my mouth instantly feels sore and I get ulceration along the junction between my cheek and lower gums. Whether this is due to the bacteria present, or to other ingredients, I have no idea but it happened on two separate occasions within a few hours of eating this brand.

Often, food intolerances are less easy to pinpoint as symptoms can develop one to seven days after eating the culprit. Cows’ milk is one of the most commonly cited triggers, possibly associated with lactose sugar, dairy proteins or bacterial remnants which cause an immune reaction.

Some people have found their mouth ulcers stopped when the cut chocolate from their diet.

It’s worth avoiding chocolate and dairy products for month to see if there is a noticeable improvement in your mouth ulcer symptoms. If you decide to stop eating dairy products long-term, however, do seek nutritional advice to ensure you continue to obtain sufficient calcium in your diet.

Do nutritional deficiencies cause canker sores in the mouth?

Nutritional deficiencies, especially lack of iron, folate or vitamin B12 are twice as common in people with recurrent mouth ulcers as within the general population. Ask your doctor if you should have blood tests to check your levels of folate, iron (as serum ferritin) and vitamin B12.

Taking a multivitamin and mineral supplement can help to correct any nutritional deficiencies that may contribute to recurrent mouth ulcers.

Does smoking cause aphthous ulcers?

If you smoke, do your utmost to stop. Toxins present in tobacco reduce immune function in the mouth, and change the nature of mouth lining cells to make ulceration more likely.

Paradoxically, stopping smoking can also trigger the appearance of mouth ulcers, as nicotine appears to suppress local inflammatory responses.

Quit-related mouth ulcers are generally mild, reduce with time, and are improved by using nicotine replacement therapy.

Do medicines cause mouth ulcers?

Certain drugs have been associated with recurrent aphthous ulcers, including angiotensin converting enzyme (ACE) inhibitors, and non-steroidal anti-inflammatory drugs such as oral propionic acid, diclofenac, and piroxicam.

If you think your medication may be to blame, ask your doctor or pharmacist for advice.

Does sodium lauryl sulfate cause mouth ulcers?

Sensitivity to a detergent, sodium lauryl sulfate (SLS), found in some brands of toothpaste, has been implicated as a possible trigger for aphthous ulcers. This was first suggested back in the 1990s, with the idea that SLS could dry out the delicate mucous mouth lining so that other irritants or infection could cause further damage.

A preliminary study asked 10 people with recurrent aphthous ulcers to use a toothpaste with and without SLS for 3 months each, and found a significant decrease in the number of ulcers when using the SLS-free product compared to when using the SLS containing product (5.1 versus 14.3 ulcers).

A larger study involving 57 people did not find any difference in the number of ulcers or pain scores, however.

More recently, a gold-standard, randomised controlled trial was carried out, involving 90 people who used two different toothpastes for 8 weeks each. While this study found the number of ulcers and frequency of attacks did not differ significantly between SLS-containing and SLS-free products, the length of time the ulcers lasted, and the degree of pain was significantly reduced when using SLS-free products. The researchers concluded that SLS can affect the ulcer-healing process, so it’s worth trying a toothpaste (and mouthwash) that is free from SLS to see if it helps your particular symptoms.

UltraDEX Low-Abrasion Toothpaste is the one I use. It is SLS and sulphate-free, with an anti-bacterial action, quickly neutralises smelly compounds, is free from alcohol, harsh abrasives and colourings and has a refreshing mint taste.

Treatment of canker sores

Different people respond to different products so not all of the approaches below will help you as an individual. If you have not tried a particular remedy before, however, you may find it helpful in reducing pain and promoting mouth ulcer healing as they all have research evidence to support their use.

Therapeutic mouth washes for aphthous ulcers

Several types of mouth wash can reduce aphthous mouth ulcers by suppressing the growth of mouth bacteria. Alcohol-free mouthwashes are less dehydrating and kinder to the mouth than those containing alcohol.

Three studies have found that chlorhexidine gel and mouthwash are more effective than placebo for reducing the duration of mouth ulceration and pain. It’s not known if they can prevent them in the first place, however.

Regular, vigorous, twice-daily use of Listerine mouth rinse can reduce the duration and recurrence or aphthous ulcers, as well as the severity of pain.

Mouth sores usually last for 7 to 10 days, but using a liquorice mouthwash (containing an extract called carbenoxolone) was shown to significantly reduce healing time. Another study involving 20 people found that using a liquorice mouthwash four times a day produced significant reductions in pain after just one day, and complete healing of aphthous ulcers after three days.

There don’t appear to be any liquorice mouthwashes available at present but there are some liquorice toothpastes on

Try a Listerine product – either one that is alcohol-free or one that is SLS-free.

Seal mouth ulcers with a barrier gel

Barrier gels stick to the surface of an aphthous mouth ulcer to provide long-lasting, antiseptic, pain relief. The protective coating is designed to adhere to the damaged ulcer surface, using a patented technology that changes the gel structure when it comes into contact with moist, mucous membranes, to suck up water like a sponge. The gel swells to form a robust protective shield around the raw ulcer, keeping out mouth bacteria and sealing in the healing factors your body produces to help the ulcer heal more quickly. The protective film also protects damaged tissue from aggravation during eating and drinking.

Iglü gel contains a local anaesthetic, lidocaine hydrochloride, for instant pain relief, plus a broad spectrum antiseptic, aminoacridine hydrochloride to suppress local bacterial activity.

Iglü gel can be reapplied as often as necessary. Clinical trials show that reapplying Iglü gel every 74 minutes, on average, allows it to remain in place at all times for ‘all of the population’. This is a considerable improvement over most mouth ulcer treatments which you need to reapply every 20 minutes or so.

In the clinical trials, 71% of people using Iglü rated its effectiveness as ‘excellent’ compared with only 19% of those using a comparator gel, while 85% rated Iglü as better than previous treatments. The healing time for ulcers when using iglü was noticeably shorter than when using the competitor (4 days compared to 5.5 days)

Iglü has a pleasant, minty flavour and is sugar-free.

Gengigel for mouth ulcers

Another of my favourite treatments is Gengigel Gingival Gel. This gel has a lovely lemon balm taste and contains hyaluronan – a molecule that attracts up to a thousand times its own weight in water. This forms an effective barrier over the raw surface of mouth ulcers to rapidly reduce pain.

Gengigel has direct antibacterial activity against mouth bacteria such as Streptococcus mutans, and helps heal aphthous ulcers more quickly, within 3 to 7 days. The range also includes a toothgel and mouth rinse. Gengigel Gingival Gel can be applied as often as needed to help heal soreness and ulceration.

Aloe vera gel

Aloe vera 2% oral gel is effective in decreasing the size and pain of recurrent aphthous ulcers, and to shorten healing times when applied three times a day for at least ten days.

Myrtle extracts

Myrtle is a shrub whose essential oils are traditionally diluted (5% strength) and used to treat mouth ulcers. When 45 people with recurrent aphthous mouth ulcers applied a myrtle oral paste, four times a day for 6 days, a significant reduction in ulcer size, pain severity, redness and oozing occured, with improved quality of life compared with episodes in which the same people used a placebo paste.

Vitamin B12 lozenges for mouth ulcers

Canker sores, or aphthous ulcers, have been linked with lack of vitamin B12. In a randomized, double-blind, placebo-controlled trial, 58 people with recurrent aphthous ulcers were asked to take either a sublingual dose of 1000mcg vitamin B12 per day, or placebo, for 6 months.

The number of ulcers, duration of outbreaks, and the level of pain experienced were significantly reduced by the end of treatment in those using vitamin B12 – whether or not their blood levels of vitamin B12 were low at the start of the trial. During the last month of the study, 74% of those using vitamin B12 lozenges had no ulcers compared with 32% of those using placebo. here ple

Probiotic lozenges

Probiotic bacteria have been used in lozenges to treat aphthous mouth ulcers. In one study, 30 people with recurrent aphthous ulcers were asked to melt in their mouth a probiotic lozenge containing the strain Lactobacillus brevis CD2 (1 billion live bacteria per dose), or a placebo lozenge, 4 times a day for a week. By the end of the trial, 14 out of the 15 people (93.3%) treated with Lactobacillus brevis CD2 showed complete remission of mouth ulcer symptoms, while in the placebo group, only 7 out of 15 (46.6%) showed complete healing. The difference between the two groups was statistically significant. Different lozenges provide different strains of probiotic bacteria and it is possible that if one hasn’t worked for you, another blend might.

Red light therapy

Red light/laser therapy has been shown to relieve the pain of mouth ulcers almost immediately, to speed healing, and reduce the chance of recurrent aphthous ulcers. Red light is believed to work by suppressing bacterial growth, boosting the activity of immune cells, reducing inflammation and soothing irritation.

Light therapy is particularly helpful if mouth ulcers are due to a herpes virus infection.

Light therapy is a pain-free treatment that can be used alongside other mouth ulcer treatments.

When to see your doctor

If you experience recurrent mouth ulcers, do seek medical advice to determine if there is an underlying cause, which will usually include tests to check your levels of vitamin B12, iron (ferritin) and folate.

Mouth ulcers often accompany other health problems such as coeliac disease (dietary sensitivity to gluten), inflammatory bowel disease, lack of white blood cells (neutropenia), and some autoimmune problems such as systemic lupus erythematosus (SLE), lichen planus, pemphigoid and Behcet’s disease. If you experience frequent mouth ulceration, you may need investigations to exclude these conditions.

It’s also important look for signs of conditions which can progress to cause mouth cancer if not treated. These include a persistent white patch or red velvety lesion. These pre-cancerous changes may cause a slight burning sensation in the mouth, but most are painless.

Most early mouth cancers are detected by dentists – an excellent reason for having a regular dental check-up, even if your teeth are perfect. It’s also worth inspecting the inside of your mouth yourself from time to time – especially if you’re over 40. Use the mirror in a dental hygiene kit to view the floor of your mouth, the sides and underneath of your tongue, and the gutters around your gums.

Always see your doctor if any mouth ulcer does not heal within three weeks.

Image credits: john_voo/flickr; madhero88/Jdcollins13/wikimedia; aleksanddra85foto/pixabay; saibo/pixabay;

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Dr Sarah Brewer ex-Medical Director (20 years)
Dr Sarah Brewer MSc (Nutr Med), MA (Cantab), MB, BChir, RNutr, MBANT, CNHC, Dip IoD qualified from Cambridge University with degrees in Natural Sciences, Medicine and Surgery. After working in general practice, she gained a master's degree in nutritional medicine from the University of Surrey. Sarah is a registered Medical Doctor, a registered Nutritionist and a registered Nutritional Therapist. She is an award winning author of over 70 popular self-help books and a columnist for Prima magazine. Her debut novel is White Powder Of Gold. Dr Sarah Brewer is a registered medical doctor, nutritionist, nutritional therapist and author of over 70 self-help books.

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