Reviewed July 2019

What does thrush look like? Spotting the signs of oral thrush

What does thrush look like Spotting the signs of oral thrush 1200400

Oral thrush, also known as oral candidiasis, is a common infection in the mouth caused by a yeast called candida. There are many forms of candida, with Candida albicans being the most common. This is the form that is responsible for causing oral thrush. Everyone carries a small amount of candida in the body and it is not contagious. It is normally found in the lining of our digestive system, skin and mouth, and is generally harmless, existing without causing problems in healthy individuals. In fact, in one study almost half of adults tested had candida albicans in their mouths.1

However, in certain conditions, candida can get out of control, causing distress and discomfort. This can occur when our immune systems are compromised because of illness or infection.2 People who receive head and neck chemotherapy or radiotherapy also have a reduced defence system against the yeast. The presence of an iron, vitamin B12, or folate deficiency can also make people prone to thrush.3 This is because these essential elements are important for the proper functioning of our immune system to stop candida from overgrowing. Similarly, severe anaemia makes us more prone to oral thrush. People who have poorly controlled diabetes may have excessive growth of candida because the yeast thrives in the sugary environment.

Smoking is also associated with thrush because smoke can irritate the oral lining, making it easier for candida to grow. Along the same lines, wearing poorly-fitting dentures may damage the mouth lining, making it easier for candida to invade. Taking certain medications, such as antibiotics or steroids, can also increase risk of thrush. This is because antibiotics kill off harmless bacteria that normally compete with candida for living space, so taking antibiotics means taking out the competition for candida, leaving them to thrive.4 A similar principle applies with excessive use of mouthwash. Mouthwash contains antibiotics, so too much can encourage candida growth.

How do we spot the signs and symptoms of thrush?

Oral candidiasis appears as thick, white or cream-coloured patches or spots in the mouth. The patches can often be wiped off, leaving a raw red area that may bleed slightly. Occasionally, the lining of the mouth may just be swollen and red, with no white spots or patches. You may notice other lesions appearing at the same time that could be associated with oral thrush, such as cracks in the corners of the mouth (angular cheilitis) and redness of the tongue (glossitis). These symptoms can be caused by vitamin deficiency — vitamins are essential for normal cell growth, so if you are lacking, the mouth corners and tongue may become inflamed.5 As explained previously, people with vitamin deficiencies are more likely to get thrush.

As well as the distinctive lesions, there may be a feeling of discomfort or burning sensation in the areas of the oral candida. This is because the candida invades and breaks the mucous lining, stimulating the pain nerves and causing the burning sensation, meaning eating and drinking can become difficult. There may be a loss of taste or an unpleasant taste in the mouth, because the yeast invasion affects the taste buds. Many people who have had oral thrush describe it as tasting “like cotton” in the mouth.

In the vast majority of cases, oral thrush may be diagnosed just by identifying the characteristic white plaques. Very occasionally, other conditions may be mistaken for oral thrush. Lichen planus is a non-infectious rash, of which the cause is unknown, that can cause white plaques in the mouth. However, these plaques are not usually associated with pain or burning and there may be rashes elsewhere, such as in the limbs, nails, and scalp. A white plaque on the side of the tongue or in the mouth may also be hairy leukoplakia. This is a condition caused by the Epstein-Barr virus, usually appearing in people who have a weakened immune system, for example those who have HIV/AIDS. These plaques are also not normally associated with any pain.

Redness in the mouth, combined with white plaques may be caused by burns from chemicals or heat. This would be painful and the redness would be similar to that found in thrush. However, the white plaques cannot usually be scraped off and there would be a history of use of chemical agent such as aspirin for toothache or burning from food. The symptoms would also resolve themselves in a week or two without specific treatment. A white plaque in the mouth, which cannot be scraped off, may also be premalignant leukoplakia.6 This is an area of abnormal mouth lining cells with an increased risk of progression to oral cancer. Therefore it is important to seek medical advice from your GP if you have a white oral plaque that does not improve, that is enlarging in size, and is perhaps associated with lumps in the neck, which could be enlarged lymph nodes.

I have oral thrush, what should I do?

Usually oral thrush can be treated successfully with a short course of antifungal medication such as nystatin, miconazole, or fluconazole. These treatments come in a variety of forms, such as topical mouthwash, suspension, gel, tablets, or capsules. Prevention is important, and improving oral hygiene, quitting smoking, and effective management of diabetes can all minimise your chances of getting oral thrush. When doctors are in doubt as to whether thrush may be the cause, or if plaques do not improve, a scraping or biopsy of the tissue may be needed. This is to have a closer look at the tissues under the microscope to make sure there are no cancerous changes to the cells which could be a cause for the lesion.

Regardless of whether your think your symptoms could be thrush, or something else, it is important to visit your doctor if you spot unusual patches in your mouth or are in pain. They will be able to advise you on the best course of action to take.

Last updated July 2019
Next update due 2021

Dr. Diana Chiu, MBChB (Hons) MRCP PGCERT (Med Ed) PhD

Diana received her medical degree, with honours, from the University of Manchester. She then went on to receive basic and specialist medical training within the north west of England. She carried out in-depth research in medicine and was awarded a PhD in 2016. Currently, she is finishing her medical training at a large teaching hospital, and one of her greatest interests is medical education. She is an advanced life support instructor and writes regularly for post-graduate examination websites, and also holds a PGCERT in medical education with distinction.

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  1. T.M. Arendorf and D.M. Walker, ‘The prevalence and intraoral distribution of Candida albicans in man’, Archives of Oral Biology, vol. 25, no. 1, 1980, p.1-10.
  2. NICE, ‘Candida – oral’, Clinical knowledge summary, National Institute for Health and Care Excellence, August 2017, [online],!diagnosisSub (accessed 3 July 2019)
  3. Samaranayake, L.P., Nutritional factors and oral candidosis, Journal of Oral Pathology, February 1986, vol 15, issue 2, pp 61-65
  4. Akpan, A., and Morgan, R., ‘Oral candidiasis’, Postgraduate Medical Journal, Vol. 78, No. 922, 2002, pp. 455-459
  5. Patil, S., et al., Clinical appearance of oral candida infection and therapeutic strategies, Frontiers in Microbiology, December 2015, [online], (accessed 3 July 2019)
  6. Carrard, V.C., and van der Waal, I., A clinical diagnosis of oral leukoplakia; A guide for dentists, Medicina Oral Patologia Oral y Cirugia Bucal, January 2018, vol 23, issue 1, pp e59-e64

With additional information from:

  1. NICE, ‘Candida – oral’, Clinical knowledge summary, National Institute for Health and Care Excellence, August 2017, [online],!diagnosisSub (accessed 3 July 2019)

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