Oral Thrush

Medically Reviewed By William C. Lloyd III, MD, FACS
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What is oral thrush?

Oral thrush is an infection of the mouth caused by a fungal microorganism called Candida albicans. Oral thrush is also known as oral candida and a yeast infection of the mouth. Oral thrush is most common in infants and is generally not a serious condition in healthy adults or infants. However, it can be uncomfortable and lead to difficulties with infant feeding if it does not resolve or is not treated.

Candida albicans normally lives in the mouth in a certain balance with other microorganisms, such as bacteria. However, some factors or conditions may cause an overgrowth of Candida albicans. These include taking antibiotics and having an impaired immune system, as occurs in organ transplant recipients, poorly controlled diabetics, and those living with HIV/AIDS.

Candida albicans can also cause a yeast or thrush infection in the vagina. Left untreated, an infant’s mouth can be exposed to and contract the candida infection during the vaginal birthing process. Candida albicans can also cause an infection in a woman’s nipples, which can then be transmitted to an infant’s mouth during breastfeeding.

Oral thrush is treatable in generally healthy people. However, oral thrush is more likely to occur and can be more difficult to treat in people with weakened immune systems due to such conditions as HIV/AIDS, diabetes, or taking steroid medications or chemotherapy. In these cases, complications of oral thrush may become life threatening.

Recurring oral thrush infections can also be a symptom of a serious, undiagnosed underlying disease, such as HIV/AIDS or diabetes. Seek prompt medical care for recurring oral thrush infections.

What are the symptoms of oral thrush?

The classic symptoms of oral thrush are yellow-white patchy lesions in the mouth, in the throat, and/or on the tongue. The lesions are raised and may appear as white streaks. The patches may become sore, raw and painful enough that it is difficult to eat and swallow.

In infants, oral thrush symptoms can include mouth, tongue, and throat lesions, as well as:

Recurrent oral thrush can be a symptom of a more serious condition, such as HIV/AIDS or diabetes. It is important to seek prompt medical care for repeated oral thrush or if you have repeated symptoms of oral thrush, such as mouth sores.

What causes oral thrush?

Oral thrush is an infection caused by a fungal microorganism called Candida albicans. Candida albicans can also cause a yeast or thrush infection in the vagina, resulting in the exposure of an infant’s mouth to the infection during vaginal birth. Candida albicans can also cause an infection in a woman’s nipples, which can then be transmitted to an infant’s mouth during breastfeeding.

Oral thrush can be caused by an overgrowth of the fungus Candida albicans in the mouth. Candida albicans normally lives in the mouth in a certain balance with other microorganisms, such as bacteria. However, certain factors or conditions lead to an overgrowth of Candida albicans, including:

  • Taking antibiotics. Antibiotics can kill off “healthy” bacteria in the body, as well as bacteria that cause disease. When antibiotics kill the healthy bacteria, the normal balance of microorganisms in the mouth and other places in the body is altered, resulting in an overgrowth of Candida albicans.

  • Having a weakened immune system due to certain conditions, such as HIV/AIDS or taking steroid medications or chemotherapy

  • Having high blood sugar due to poorly controlled diabetes, which hinders host immunity and allows for Candida albicans overgrowth

Vaginal thrush can be passed from a pregnant woman to her infant’s mouth during vaginal delivery. In addition, a yeast infection in a woman’s nipples can be passed to her infant’s mouth during breastfeeding.

What are the risk factors for oral thrush?

A number of factors increase the risk of developing oral thrush. Not all people with risk factors will develop oral thrush. Risk factors include:

  • Being very young or very old

  • Having poorly fitting dentures

  • Having a weakened immune system due to such conditions as HIV/AIDS or taking steroid medications, immunosuppressive drugs, or anticancer chemotherapy

  • Having high blood sugar due to poorly controlled diabetes, which hinders host immunity and allows for Candida albicans overgrowth

  • Taking strong antibiotics, especially for long periods of time

Reducing your risk of oral thrush

You can lower your risk of developing oral thrush or transmitting it to your infant by:

  • Avoiding douching when pregnant

  • Cleansing the genitals daily with mild soap and water

  • Eating a well-balanced, healthy diet

  • Ensuring dentures fit properly

  • Following your treatment plan for conditions such as diabetes and HIV/AIDS

  • Getting early and regular prenatal care when pregnant

  • Maintaining good oral hygiene and seeking regular dental care

  • Not using feminine deodorants when pregnant

  • Not wearing tight-fitting underwear, thongs, jeans, or other pants if you are pregnant

  • Taking antibiotics only when prescribed by your health care professional and finishing the medication exactly as directed

  • Wearing cotton underwear when pregnant

In addition, nursing women who have nipple discharge or breast pain should notify their provider so they can be examined for oral thrush of the nipples, which could be transmitted to the mouth of a nursing infant.

How is oral thrush treated?

Treatment of oral thrush begins with seeking regular medical care throughout your life. Regular medical care allows your health care professional to assess your risks of developing oral thrush and promptly order diagnostic testing for oral thrush and possible underlying conditions, such as diabetes. These measures greatly increase the chances of diagnosing and treating underlying causes of oral thrush in their earliest stages.

Oral thrush treatment includes:

  • Antiseptic mouthwashes

  • Diagnosing and treating any underlying diseases such as HIV/AIDS and diabetes. Treating the high blood sugar levels of diabetes may resolve a current infection of oral thrush and is critical to minimizing the risk of developing recurrent infections.

  • Eating yogurt or taking acidophilus supplements, which can help correct the abnormal balance of microorganisms in the mouth

  • Medications, including prescription oral antifungal medications such as fluconazole

  • Warm salt-water mouth rinses

In many cases, oral thrush in infants can disappear within two weeks and may need no treatment other than watching the progress of the mouth lesions. Because oral thrush may be painful and affect feedings, the pediatrician should still be notified if symptoms appear in an infant.

What are the possible complications of oral thrush?

Complications of oral thrush can be serious for people with weakened immune systems, such as those with HIV/AIDS or those on chemotherapy or taking steroid medications. In these cases, candidiasis can spread throughout the body, causing yeast infections in vital organs, such as the heart and the brain. This can result in critical, life-threatening complications, such as:

Seek prompt medical care if you are experiencing symptoms of candidiasis and you have diabetes or HIV/AIDS, are being treating with immunosuppressive drugs or anticancer chemotherapy, or are taking steroid medications.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Jan 15
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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