Canker Sore – Mouth Thrush Causes and Treatment

What is a canker sore?

A canker sore, also called aphthous ulcer or aphthous stomatitis, is a small ulcer that can appear in almost any point of the oral cavity: tongue, lips, gums, throat, uvula, etc. They are oval lesions, whitish (sometimes yellowish), shallow and clean, that is, they do not present pus, bacteria or other signs of infection. They can be single or multiple, small or large.

Canker sores are very painful and often disrupt simple activities such as talking, eating, and kissing. Fortunately, the lesions are benign and don’t usually cause any major problems other than this discomfort. However, some more serious diseases of the oral cavity can present with very similar ulcerated lesions, which can cause some confusion. One example is cancer of the oral cavity, which in the early stages can look like a canker sore.

Everyone has had at least one canker sore in their lifetime and 20% of the population suffers from recurrent canker sores. They are more common in pre-teens, adolescents and young adults, tending to decrease their incidence over the years.

Most thrush last, on average, one to two weeks and usually heal without scarring. The canker sores that take longer to cure are those that appear in places where there is constant contact with teeth or food, suffering repeated trauma throughout the day.

Some people have large thrush, called  major thrush , larger than 1 cm and deep. These take up to six weeks to disappear and can leave a scar. There is also the sore herpetiformis, formed by multiple small ulcers that join together and transform into a large lesion. These canker sores can be accompanied by lymph nodes in the neck (buttered in the gullet) and sometimes with low-grade fever and malaise.

No matter how large and numerous they are, canker sores do not usually cause bad breath .

Causes of Thrush

Thrush is not contagious, but its causes are not fully understood. They appear to be caused by imbalances in the immune system. Some of the known triggers are:

  • Local trauma such as accidental bites.
  • Psychological stress.
  • Few hours of sleep.
  • Helicobacter pylori , the same bacterium that causes gastric ulcers.
  • Some toothpastes containing sodium lauryl sulfate.
  • Gastroesophageal reflux .
  • Foods such as chocolate, coffee, soft drinks, tomatoes and pineapple.
  • Cigarette .
  • Hormonal changes during the menstrual cycle.
  • Deficiency of some vitamins and minerals, such as vitamin B12, vitamin C, zinc, iron or folic acid.
  • Medicines: anti-inflammatory , rapamycin, captopril, methotrexate, aspirin and atenolol.

Some people who have the habit of lying down shortly after the last meal may have recurrent canker sores. This fact is probably related to some degree of gastroesophageal reflux, which leads to increased acidity in the oral cavity. Canker sores usually appear a day or two later, making patients often not relate one fact to another.

A genetic predisposition to the development of recurrent thrush is strongly suggested by the fact that 40% of patients have a positive family history, with frequent thrush since childhood.

Treatment for canker sore

There is no miracle cure for canker sore. No substance heals the ulcer overnight. As canker sore usually lasts up to two weeks, current treatments are aimed at accelerating the healing process of the lesion.

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It is important to distinguish ointments that contain only anesthetics, which serve only for symptomatic relief, from those with steroids and anti-inflammatory drugs in their formula, which can effectively accelerate healing.

canker sore Remedies

The two most commonly used medications to accelerate the healing of thrush are:

  • Amlexanox (Aphthasol® or Aftaid®).
  • Triamcinolone Acetonide (OMCILON-A ®).

Amlexanox is what has shown the best results in scientific work. Unfortunately, until the last update of this article, I have not found any pharmacy that sells Amlexanox in Brazil. Apparently, the drug is not yet available in the country. In Portugal, the drug is already available and is sold under the trade name Aftaid.

Cauterization of canker sore with silver nitrate is another option capable of reducing the pain caused by the lesion.

All other thrush drugs sold in pharmacies are basically a variation of topical anesthetics with bicarbonate and antibiotics.

Drugs that have anesthetics, such as lidocaine, benzocaine, or procaine, can help because they can temporarily eliminate pain, which can be helpful for patients whose canker sores cause difficulty eating.

home treatment

On the Internet it is very easy to find countless homemade recipes to treat thrush. Care must be taken with what is applied to the lesion so as not to increase inflammation and worsen the condition.

The problem with home treatments is that a good part of them has never been studied in scientific works, therefore, there is no scientific proof of their effectiveness or safety.

Some acceptable options are:

  • A mouthwash solution made with a spoonful of milk of magnesia or baking soda diluted in a glass of water.
  • Dilute hydrogen peroxide in common water and apply with a cotton swab directly on the sore.
  • Mix Diphenhydramine (Benadryl®) with Milk of Magnesia and rinse.

Avoid direct contact with pure abrasive substances such as alcohol, salt or baking powder.

Alcohol mouthwashes can also irritate the canker sore and worsen the condition. When using mouthwash dilutions, always spit out the liquid at the end, never swallow it.

Toothpaste is not good for treating canker sores and can make them worse, as many brands contain sodium lauryl sulfate.

When to worry about a canker sore?

Despite being benign in the vast majority of cases, canker sore can be a manifestation of systemic diseases or it can be confused with serious lesions, such as neoplasms of the oral cavity.

An appointment with the dentist or stomatologist should be evaluated when:

  • The canker sore is exceptionally large.
  • The canker sores are recurrent, with the appearance of new lesions soon after the first ones heal.
  • The canker sore takes more than three weeks to heal.
  • There are signs of infection in the canker sore area.
  • There are systemic symptoms, ie: fever, tiredness, malaise, weight loss, loss of appetite or any other symptom that suggests the presence of a disease behind the canker sores.
  • There are also ulcers on Organs genitals.
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What are the diseases that cause thrush or similar injuries?

Usually, oral ulcers caused by systemic diseases are multiple and recurrent. They tend to have some characteristics that are different from common canker sores and come with other symptoms. Some examples:

  • In patients with lupus , canker sores are usually painless and are accompanied by skin lesions and joint pain, in addition to some systemic symptoms, such as low-grade fever and tiredness.
  • In Behcet’s disease, which is also an autoimmune disease , canker sores are multiple, recurrent and are usually accompanied by ulcers on the genitals. In Behcet’s disease, eye damage is also common.
  • In celiac disease and Crohn’s disease , canker sores come together with intestinal symptoms such as diarrhea and bloody stools .
  • Neutropenia, which is a drop in the number of neutrophils (a type of white blood cell) in the blood, is also a cause of oral ulcers. Neutropenia usually appears as a side effect of chemotherapy, but it can occur in some diseases that attack the immune system.
  • Some cancers of the oral cavity may present as ulcerations and are initially confused with common canker sores. Therefore, any canker sore that takes a long time to heal must be evaluated by a doctor, especially if the patient is a smoker.

Several infections can cause oral ulcers similar to thrush, some examples are:

  • The HIV virus can cause oral ulcers in advanced stages of the disease, when there are already criteria for AIDS , but also in the acute stage of the virus infection .
  • Coxsackie virus (herpangina) infection , very common in children, can lead to sore throat, fever, small oral ulcers, and lesions on the palms and soles of the feet.
  • The syphilis , both the primary stage and the secondary, can be associated with oral ulcers. Typically, canker sores are multiple and take a long time to heal.
  • The canker sore  appears as blisters that can turn small ulcers after rupturing. The appearance is not very like canker sore, but it can be confused by laymen. Despite having similar lesions, herpes and canker sore are two different diseases, with different etiologies and treatments.

Most common questions

1. I have recurrent thrush, does that mean I have any illness? 

No. Up to 20% of the population suffers from recurrent thrush without this indicating the presence of another disease.

2. Does everyone who regularly get thrush have stomach problems?

No. In fact, only a small proportion of these people have any gastric problems.

3. I have a big canker sore in my mouth and I noticed an enlarged ganglion in my neck. Is one thing related to another?

Can be. The presence of lesions in the oral cavity can be the cause of enlarged lymph nodes in the neck. The same reasoning applies to lesions on the face and scalp.

4. Every time I accidentally bite my lips or tongue I get a canker sore. This is normal?

Yes. Trauma in the oral cavity is one of the main causes of thrush.

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5. I’ve heard that putting bicarbonate on the canker sore helps to heal the sore. Does this proceed?

Yes and no. Avoid placing baking powder directly on the canker sore, as this can cause irritation and increase inflammation. However, rinsing with a teaspoon of baking soda diluted in a glass of water is one of the suggested home treatments.

6. What are the foods that should be avoided when there is an active canker sore?

Acidic foods such as citrus juices and sodas, foods with a lot of salt, condiments or spicy foods. Also try to avoid very hard foods that can injure and irritate the sore even more while chewing.

7. Does putting Royal powder on the sore help to heal it?

No. On the contrary, it can aggravate the injury.

8. Does putting toothpaste on the canker sore help it to heal?

No. In fact, some types of toothpaste can even make lesions worse.

9. Sticking the canker sore with a needle helps with healing

No, and it could make the situation worse.

10. Whenever I eat pineapple, I get thrush. Does this make sense?

Yes. Some people have a kind of allergy to certain foods, causing them to develop thrush. The most cited are walnut, hazelnut, cinnamon, pineapple and other citrus fruits.11. Can canker sore cause fever?

Yes, but in these cases a medical evaluation is always indicated to rule out other causes, since the vast majority of thrush does not cause fever.

12. Whenever I sleep on a full stomach I get a canker sore in the following days. Does this make sense?

Yes. People who have gastroesophageal reflux have worsening of the condition if they lie down right after eating. This can increase the acidity of the mouth and cause canker sores.

13. Can H.pylori bacteria cause thrush?

Yes, you can.

14. Is canker sore transmitted by kissing? 

No. canker sore is not a communicable disease. However, some infectious diseases, such as syphilis, can cause contagious oral ulcers.

15. Can stress cause thrush?

Yes, you can.

16. How many days does a canker sore last?

On average 7 days.

17. Does the presence of canker sore in the mouth increase the risk of transmission of sexually transmitted diseases during oral sex?

Theoretically yes, however, there are no studies that effectively demonstrate what the real risk is.

18. Can a canker sore be confused with canker sores?

Yes, smoking favors the appearance of canker sores in the mouth and tongue. Some people also get canker sores soon after quitting, due to the stress they go through the first few days without smoking

.20. Can canker sore become cancer?

No, thrush are benign lesions. However, some mouth cancers can manifest as non-healing canker-like oral ulcers.