Thrush is a yeast infection of the mucus membrane lining of the mouth and tongue.
Overview, Causes, & Risk Factors
Thrush is caused by forms of a fungus called Candida. A small amount of this fungus lives in your mouth most of the time. It is usually kept in check by your immune system and other types of germs that also normally live in your mouth.
However, when your immune system is weaker, the fungus can grow, leading to sores (lesions) in your mouth and on your tongue. The following can increase your chances of getting thrush:
- Taking steroid medications
- Having an HIV infection or AIDS
- Receiving chemotherapy for cancer or drugs to suppress your immune system following an organ transplant
- Being very old or very young
- Being in poor health
Thrush is commonly seen in infants. It is not considered abnormal in infants unless it lasts longer than a couple of weeks.
Candida can also cause yeast infections in the vagina.
People who have diabetes and had high blood sugar levels are more likely to get thrush in the mouth (oral thrush), because the extra sugar in your saliva acts like food for Candida.
Taking high doses of antibiotics or taking antibiotics for a long time also increases the risk of oral thrush. Antibiotics kill some of the healthy bacteria that help keep Candida from growing too much.
People with poorly fitting dentures are also more likely to get thrush.
Pictures & ImagesMouth anatomy
The mouth is the origination of the digestive tract. The teeth and salivary glands aid in breaking down food for digestion. The tonsils aid against infections.Candida, flourescent stain
This microscopic film shows a fluorescent stain of Candida. Candida is a yeast (fungus) that causes mild disease, but in immunocompromised individuals it may cause life-threatening illness. (Image courtesy of the Centers for Disease Control and Prevention.)
Review Date : 8/28/2009
Reviewed By : David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.