What is Oral Thrush? | Guardian Direct

What is oral thrush?

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Oral thrush, or oral candidiasis, is a fungal infection that can happen in the mouth, esophagus or throat.

The fungus that causes oral thrush, called Candida, appears normally on and in the human body. In fact, it occurs naturally in 30% to 50% of patients under 60 and 60% of people over 60.¹

Oral thrush is not life-threatening but can be a nuisance as the fungi multiply, creating white lesions on the tongue. Thrush can cause irritation in the mouth and can be a sign that a person has an immune system that is not working properly.²

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Who gets oral thrush?

While it is possible for anyone to develop an advanced case of oral thrush, it is unusual for healthy adults to develop it. It’s more likely to affect babies and older adults, and those with weakened immune systems. Oral thrush is considered contagious, however, the risk of spreading between healthy adults is low.³

Oral thrush in babies

Babies under one month in age and toddlers are at higher risk of developing thrush because they do not have an established immune system that is able to right off the proliferation of the fungus.

Newborns often get thrush from breastfeeding. This happens because every human has the Candida fungus on them naturally and the mouth to breast contact spreads the fungus from mother to baby. Babies can also transmit oral thrush to their mother during breastfeeding.⁴

Oral thrush in adults

Most healthy adults will not get oral thrush. When an adult does develop oral thrush, they are likely to have one of the follow risk factors present:⁵

  • Pregnancy – The change in hormones during pregnancy can cause the Candida fungus to spread more readily

  • Birth control – Similar to pregnancy, the change in hormones associated with birth control pills can create an environment where the fungus can grow and spread

  • Diabetes that is not controlled – High blood sugar and a weakened immune system both allow thrush to thrive in people with diabetes. Having diabetes under control can help reduce instances of oral thrush

  • Smoking – Smoking can kill good bacteria in the mouth that prevent Candida from spreading. Smoking also can cause dry mouth, which is conducive to growing and spreading the fungus

  • Taking antibiotics – One of the main protectors against oral thrush is the “normal flora” bacteria, or the bacteria that occur naturally all over our body. These bacteria out compete Candida and prevent it from growing. When a person is on antibiotics, their normal flora can be destroyed or disrupted allowing oral thrush to grow

  • Dry mouth – Our saliva provides an environment that allows the normal flora to thrive and keeps unwanted growth of oral thrush in check. 

  • An “off” or strange taste in their mouth Oral thrush can cause a metallic taste in the mouth

  • Weakened immune system – Most people who get thrush in the esophagus have weakened immune systems, including people with HIV or AIDS. People with cancer or undergoing chemotherapy or radiation are more likely to develop oral thrush. In both cases the body’s immune system has been weakened and cannot keep the fungus in from multiplying

Symptoms of oral thrush

Symptoms of oral thrush are similar in both babies and adults and include:⁶

  • White or creamy patches in the mouth, throat, or cheeks.

  • Pain eating or swallowing

  • Redness and a sore mouth or throat

  • Inability to taste as well as before

  • Cracking at the edges of the mouth

Diagnosis of oral thrush

Most of the time thrush can be diagnosed by simple observation from a doctor looking for the white lesions that are present with oral thrush. Doctors may take a sample to verify that the creamy lesions are actually thrush.

In extreme cases, or if the pain is only in the esophagus, the doctor may order and endoscopy to determine if there are lesions in the esophagus. An endoscopy is a procedure where the doctor snakes a small camera and light down their patient’s esophagus to see if there are abnormalities.⁷

Oral thrush treatment

In infants and babies, it is usually acceptable to simply let the condition run its course. As the baby’s immune system becomes stronger it will be able to fight of the Candida fungus on its own.

Oral thrush home remedies

Thrush can be treated with a variety of home remedies with varying success. These include the following:⁸

  • Yogurt – it increases the amount of good bacteria in the mouth which can prevent thrush from spreading.

  • Saltwater or baking soda rinse – rinsing your mouth with a solution of saltwater or baking soda can kill or prevent oral thrush in your mouth.

  • Lemon juice – the acidity in lemon juice acts as an antifungal. 

  • Apple cider vinegar – when swished in the mouth this can prevent fungus from growing, including the Candida fungus.


Doctors may also prescribe antifungal medication, especially in cases where the patient has a compromised immune system. These medications include miconazole, clotrimazole, or nystatin and are applied to the mouth for a week or two. If symptoms do not stop or if the case is severe, doctors may prescribe fluconazole that must be administered orally or intravenously.⁹

Links to external sites are provided for your convenience in locating related information and services. Guardian, its subsidiaries, agents and employees expressly disclaim any responsibility for and do not maintain, control, recommend, or endorse third-party sites, organizations, products, or services and make no representation as to the completeness, suitability, or quality thereof.

Brought to you by The Guardian Life Insurance Company of America (Guardian), New York, NY. Material discussed is meant for general illustration and/or informational purposes only and it is not to be construed as tax, legal, investment or medical advice. This is not dental care advice and should not be substituted for regular consultation with your dentist. If you have any concerns about your dental health, please contact your dentist's office.


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  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4211245/, 2014

  2. https://www.mayoclinic.org/diseases-conditions/oral-thrush/symptoms-causes/syc-20353533, 2018

  3. https://www.mayoclinic.org/diseases-conditions/oral-thrush/symptoms-causes/syc-20353533, 2018

  4. https://www.colgate.com/en-us/oral-health/life-stages/infant-kids/oral-thrush-in-babies--causes--symptoms-and-treatment (Last accessed February 2020)

  5. https://www.mayoclinic.org/diseases-conditions/oral-thrush/symptoms-causes/syc-20353533, 2018

  6. https://oralb.com/en-us/oral-health/conditions/oral-thrush/oral-thrush-symptoms-causes-treatments#OralThrushInBabiesAndNewBorns (Last accessed February 2020)

  7. https://www.cdc.gov/fungal/diseases/candidiasis/thrush/index.html, 2019

  8. https://www.healthline.com/health/home-remedies-for-thrush#home-remedies, 2018

  9. https://www.mayoclinic.org/diseases-conditions/oral-thrush/diagnosis-treatment/drc-20353539, 2018

Brought to you by The Guardian Life Insurance Company of America (Guardian), New York, NY. Material discussed is meant for general illustration and/or informational purposes only and it is not to be construed as tax, legal, investment or medical advice.(exp.02/22)

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