Oral thrush

Oral thrush, also called oral candidiasis, is an infection caused by Candida albicans, a type of fungus that is present in the oral cavity of many of us but in a saprophytic form, without causing any type of pathology.

oral thrush

It is estimated that around 50% of the healthy population has this fungus in the oral cavity, this percentage being even higher as the person gets older, which makes this pathology more and more important due to an ever increasing life expectancy.

However, the presence of this fungus in the mouth is usually as a commensal species, that is, although it lives inside us, it does so in a balanced way, in homeostasis, together with the rest of fungi and bacteria that are part of the oral microbiota and can thus be there without causing any kind of pathology or infection.

The problem arises when there is an overgrowth of this fungus Candida albicans, so that it stops living as a commensal to become a pathogenic species and cause the infection.

Oral Thrush Symptoms

It is an opportunistic infection, that is, the fungus takes advantage of a situation of an immune system that for some reason is more weakened, to grow and exercise its pathogenic effect causing the infection. This is when the first symptoms of thrush appear in the mouth: whitish plaques on the tongue and in the rest of the oral cavity. All this is often accompanied by difficulty in swallowing and pain.

woman with angular cheilitis

Candida infections may be accompanied by conditions such as

  • Stomatitis (inflammation of lips and mouth) which is aggravated by the use of dentures.
  • Angular cheilitis. Commonly known as “boqueras”, which appear at the corner of the lips.
  • Median rhomboidal glossitis. A colored, reddish stain on the back of the tongue.

Oral Thrush Causes

There are different reasons why this fungus can cause candidiasis in the mouth:

  • An immune system compromised by some type of treatment (e.g. chemotherapy treatment) so that Candida albicans becomes an opportunistic pathogen taking advantage of the changes that have occurred in the patient’s microbe as a result of these treatments.
  • Stress situations, related by the increase of cortisol that is produced in these situations and that give rise to a weakness of the immune system. Let us not forget the direct relationship between cortisol and stress.
  • Pathologies that imply a deficient salivation (xerostomia) since there is a lower antibacterial and antifungal capacity of the saliva that is provided by proteins such as lysozyme, lactoferrin or sialoperoxidase.
  • Use of dental prostheses or dentures since their use causes a reduction in the salivary flow in the area of adhesion of the prosthesis to the gum. In addition, anaerobic conditions are generated in this same area, with a low level of oxygen that favors the presence of Candida albicans. The risk may even increase if the dentures are not hygienically well maintained.
  • The origin of this infection is also related to deficiencies of some vitamins (Vitamin B6, Vitamin B12 or Vitamin A) as well as iron deficiency.
  • In the case of newborns with oral thrush, it usually has its origin in the passage through the birth canal of a vagina infected with vaginal candidiasis.
  • Treatment with inhaled corticosteroids (e.g. Fluticasone) can produce oral thrush due to a possible suppression of part of the cellular immunity.
  • Diets rich in carbohydrates such as glucose, which promote the adhesion of candida to epithelial cells.
  • Treatment with broad-spectrum antibiotics that alter the microbiota or oral flora and promote the growth of opportunistic species.
woman with oral thrush

Oral Thrush Treatment

Since it is a fungal infection, the most effective treatments are based on antifungal drugs such as nystatin, miconazole or fluconazole.

These drugs are usually applied in the form of an oral suspension so that when administering it, one should try to keep it in the mouth as long as possible before swallowing the product, acting as antifungal mouthwash. This way, a longer time of direct contact between the drug and the fungus that is causing the infection is achieved.

If, in addition, the patient wears dentures, it is important that the dentures be washed or brushed using the drug to try to eliminate the presence of the fungus on the dentures themselves.

Treatment of oral thrush with probiotics

Probiotics are having a big boom in recent years. They are being used in Irritable Bowel Syndrome, in treatments for diarrhea, in intestinal discomfort. Part of the mechanism of action of probiotics is based on the movement that the “good” bacteria in the body (the probiotic) make against pathogenic microorganisms.

In the case of oral thrush, one of the probiotics that have demonstrated an improvement in the treatment of these mouth fungi is Bacillus clausii (1) where it was shown that this probiotic reduces the signs and symptoms of this pathology when administered as an adjuvant to pharmacological treatment.

Other probiotics such as Lactobacillus paracasei and Lactobacillus rhamnosus, Lactobacillus reuteri have demonstrated their ability to reduce the presence of Candida albicans by modifying oral pH or other mechanisms of action (2).

Some probiotics that we can find online with these probiotic species with activity against oral thrush or candidiasis are:

(1) Nirmala M, Smitha SG, Kamath GJ. A Study to Assess The Efficacy of Local Application of Oral Probiotic in Treating Recurrent Aphthous Ulcer and Oral Candidiasis. Indian J Otolaryngol Head Neck Surg. 2019 Oct;71(Suppl 1):113-117. doi: 10.1007/s12070-017-1139-9. Epub 2017 May 4. PMID: 31741944; PMCID: PMC6848315.

(2) Mundula T, Ricci F, Barbetta B, Baccini M, Amedei A. Effect of Probiotics on Oral Candidiasis: A Systematic Review and Meta-Analysis. Nutrients. 2019;11(10):2449. Published 2019 Oct 14. doi:10.3390/nu11102449