Oral Thrush: A Common Fungal Infection of the Mouth

Oral Thrush
Among oral diseases, oral thrush, a common fungal infection caused by Candida albicans, is known to be uncomfortable and annoying.

While oral thrush in healthy people is usually mild and self-resolving, it can worsen and lead to complications in more vulnerable individuals.

In this article, we'll discuss how Candida albicans leads to oral thrush, ways to recognize it, the associated risk factors, the groups most vulnerable, available treatments, and strategies for restoring a healthy oral microbiome.

What is Oral Thrush?

Oral thrush, also known as Candidiasis, is a mouth infection caused by a fungus called Candida. While various candida species can trigger it, most cases are due to Candida albicans.

Many healthy people carry Candida albicans in their mouth, skin, and digestive tract. It coexists harmlessly with other microorganisms. However, when the balance among these microorganisms is disrupted, candida albicans can multiply excessively and cause an infection known as Oral Thrush.

How Does Candida Albicans Induce Oral Thrush?

When Candida albicans multiplies uncontrollably, it forms a thick film called biofilm. Think of this biofilm as a protective habitat that helps them to survive and increase their resistance.

Candida albicans invading tissues

As candida albicans thrives in the mouth, it can induce hypersensitivity reactions and produce toxins that allow it to invade tissues.

In most cases, oral thrush is limited to the lining skin of the mouth. But occasionally, it can become more severe, affecting deeper structures like the esophagus and lungs, especially in older individuals with weaker immune systems.

What Causes Oral Thrush?

Oral thrush doesn't have a specific and direct cause. Instead, it results from underlying factors that weaken the immune system and disrupt the balance of the oral microbiome.

It affects newborns (approximately 5%) and elderly individuals (up to 10%) more often due to their weak immune response.

Young people are the least affected unless they have risk factors. These include:

  1. Poor oral hygiene: Neglecting regular brushing and flossing allows harmful bacteria to grow at the expense of friendly ones. This creates an ideal environment for oral yeast to flourish.

  2. Smoking: Smoking reduces the blood flow to the mouth tissues and prevents immune cells from functioning properly. As a result, the balance of the oral microbiome gets disrupted, increasing the risk of oral thrush.

  3. Ill-fitting dentures: Besides living oral tissues, candida albicans can colonize abiotic non-living tissues as well, like dentures. In fact, denture wearers are more susceptible to oral thrush. (3)

  4. Dry mouth: Saliva plays a vital role in maintaining oral microbiome balance. When the mouth lacks saliva, harmful bacteria and yeasts can overgrow, increasing the risk of infections.

  5. A diet rich in carbohydrates: A diet high in carbohydrates can fuel the growth of oral yeast and contribute to thrush.

  6. HIV infection: Individuals with HIV have weakened immune systems, making them more vulnerable to oral thrush.

  7. Certain medications: Some medications, such as antibiotics and corticosteroids, can weaken the immune system and disrupt the oral microbiome.

  8. Cancers and their treatment: Cancer patients undergoing chemotherapy or radiotherapy are more susceptible to oral problems such as dry mouth and infections.

Symptoms of Oral Thrush

Oral thrush can manifest differently depending on its form and severity.

Typically, the lesions remain confined to the mouth, appearing as noticeable plaques that cover specific areas.

The most common form is known as Acute Pseudomembranous Candidiasis. It presents as smooth, thick, creamy-white, or yellow plaques that can be easily wiped off. They can occur in different regions of the mouth, including the tongue, roof of the mouth, gums, and inside the cheeks.

The white stuff consists of a mixture of dead cells, yeast, and inflammatory products. When removed, they leave behind reddish, bleeding, and sore areas. These symptoms are often accompanied by a burning sensation, dry mouth, and alterations in taste, sometimes described as a metallic taste.

When the acute form persists for longer or is resistant to treatment, it develops into Chronic Candidiasis. Chronic candidiasis appears as thick, enduring, and irregular white patches with a rough surface.

Unlike the acute form, the white plaques of chronic candidiasis cannot be removed by scrubbing. This is because the thickening is not due to a buildup of material but rather an overproduction of keratin by the underlying cells in response to the infection. This leads to an increase in tissue thickness, a condition known as Hyperplasia. In rare cases, these lesions can induce malignant transformations (cancer). (4)

Another form of oral thrush is Candida-associated Angular Cheilitis. As the name suggests, it primarily affects one or both corners of the mouth where the lips meet. This condition often leads to soreness, redness, and the development of red cracks that can extend onto the nearby skin, causing discomfort and cosmetic concerns.

Can Oral Thrush Get Worse?

Most cases of oral thrush respond well to treatment and improve within a few weeks. However, without treatment and in the presence of underlying medical conditions, oral thrush can worsen and lead to severe and sometimes fatal complications.

The fungal infection can spread to the esophagus, lungs, heart (Candidal Endocarditis), or brain (Candidal Meningitis).

oral thrush complications

When the fungus spreads throughout the body via the bloodstream, it can lead to a fatal complication known as Candida Septicemia. In this case, the whole body becomes stressed and reacts to the infection, potentially resulting in organ failure.

Other Oral Conditions That Resemble Candidiasis

Several oral conditions can resemble oral thrush, causing white patches and discomfort. These include leukoplakia, lichen planus, geographic tongue, and traumatic ulcers.

  1. Leukoplakia: White or grayish patches that can appear in any area of the mouth. Some may be precancerous.

  2. Lichen Planus: Autoimmune condition causing white patches, redness, or sores in the mouth.

  3. Geographic Tongue: Tongue with changing map-like patterns, often painless.

  4. Traumatic Ulcers:Painful mouth sores from physical injury or irritation. Usually, they heal on their own after removing the trigger.

That's why when encountering such lesions, it is recommended to seek the expertise of a dentist or physician for a thorough examination, appropriate tests, and an accurate diagnosis.

How Is Oral Thrush Treated?

Treatment depends mainly on the form, severity of oral thrush, and your overall health.

Most cases are mild, not even requiring particular treatment, except for some home measures.

Your priority should be rebalancing your oral microbiome through dietary improvements and better oral hygiene practices while identifying and stopping all risk factors. This may involve quitting or decreasing smoking, cutting down on dietary carbohydrates, treating dry mouth, and cleaning your dentures regularly.

If you suspect antibiotics or corticosteroids are contributing, talk to your doctor about changing your medication or reducing the dosage.

You can also do a baking soda rinse by adding half a tablespoon of baking soda to a glass of water, which you can do several times a day. Numerous studies have highlighted its antimicrobial properties, particularly effective against candida albicans. (5)

However, if your symptoms don't improve after 14 days, it's time to seek professional help. When diagnosed with oral thrush, the primary treatment involves applying antifungal creams or gels directly to the affected areas. Apply these medications between meals and keep them in contact with the patches for as long as possible. This treatment usually lasts one to three weeks.

In more severe cases or if you have an underlying condition, your doctor may recommend antifungal tablets in addition to topical treatment.

How to Maintain an Optimal Oral Microbiome

Preventing oral thrush involves maintaining a balanced oral microbiome. Achieving this involves strengthen your immune system and promoting beneficial bacteria. Here are some helpful tips:

  • Maintain good oral hygiene: Brush your teeth at least twice a day with a soft toothbrush and floss daily to disrupt the biofilm on your teeth surface. This biofilm, which contains bacteria and yeast, is a primary contributor to mouth infections like cavities, gum disease, and thrush.

  • Clean your tongue: The tongue can also collect plaque and food debris. If not cleaned regularly, a white coating can form, which can lead to problems such as bad breath and infections. Use a toothbrush or, even better, a tongue scraper once a day to maintain tongue hygiene.

  • Control your overall health: Medical conditions such as diabetes, HIV infection, cancers, and diseases requiring corticosteroids can weaken your immune system, promoting candida albicans overgrowth in your mouth. Managing these conditions by controlling blood sugar and following your doctor's advice and treatment helps prevent associated complications.

  • Reduce sugars: Sugars act as fuel for yeast and harmful bacteria in the mouth. Avoid foods rich in sugar or refined carbohydrates and opt for natural antifungal options like garlic, ginger, olive oil, and onions. Probiotic foods such as cheese and yogurt can also help reduce the candida albicans count in the mouth. (6)

  • Go easy on mouthwashes: Using mouthwashes or antimicrobial agents excessively can disrupt your oral microbiome. When incorporating mouthwash into your oral hygiene routine, consult your dentist for guidance and always follow the recommended instructions.

  • Try oil pulling: Oil pulling involves swishing oil in your mouth for 15 to 20 minutes. This technique has been shown to significantly reduce the bacterial load in the mouth. You can use any oil, but coconut oil or olive oil are particularly effective for their anti-fungal properties.