Oral Thrush: Causes, Symptoms and Treatment

Oral thrush is caused by a fungal infection of the mouth and tongue. It is caused by a group of yeast organisms called Candida, and is also known as oropharyngeal candidiasis. It is normal to have a small amount of these fungal organisms living in your mouth and gastrointestinal tract without causing any harm, but if they start to multiply uncontrollably, you can develop an infection. Oral thrush is usually a mild infection which is easily treatable with antifungal medications, but it can also be an indication of a weakened immune system, such as in people with poorly-controlled diabetes, cancer, and untreated HIV/AIDS infection.

Yeast Infection (Thrush)

Some common symptoms of oral thrush are:

  • Whitish or reddish patches on the tongue, inner cheeks, tonsils and gums
  • Pain or burning sensation around the tongue and mouth
  • Altered taste or loss of taste over the tongue
  • Painful cracks at the corners of the mouth
  • Difficulty swallowing (with esophageal candidiasis)

Typically, the white coating in oral thrush can be scraped off to reveal reddish, raw patches underneath (which can sometimes bleed slightly). This usually helps to differentiate it from other lesions such as lichen planus or oral hairy leukoplakia, where the lesions cannot be wiped away. While it is usually diagnosed clinically through appearance and history, you will sometimes need other tests such as a fungal smear or biopsy to confirm the diagnosis and rule out other similar-looking conditions.

STD Symptoms in Receptive Oral Sex

Oral candidiasis is an opportunistic infection, where a normally harmless organism takes advantage of a weakened immune system and causes an invasive infection. It is not considered contagious or transmissible through kissing or sharing food and utensils.

Some conditions can predispose an individual to get an infection, including:

  • Prolonged or high dose antibiotic use
  • Prolonged or high dose corticosteroid use, including steroid-based inhalers for asthma
  • Cancers such as leukemia, or undergoing treatment such as chemotherapy or radiation therapy
  • HIV infection / AIDS
  • Poorly-controlled diabetes
  • Ill-fitting dentures and poor dental hygiene
  • Cigarette smokers

Infections can usually be treated with a short course of antifungal medications, but it would also be important to investigate for underlying conditions. It is rare to get complicated infections unless someone is immuno-compromised, in which case it can enter the bloodstream and spread to other organs such as the brain, heart and liver.

If you suspect you may have oral thrush or any related conditions, it is best to see a doctor early to get a proper assessment. If you are in or around Singapore, please make an appointment with any of our clinics to have a complete evaluation by our specially-trained doctors.


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