DefinitionThrush is a yeast infection of the mucus membrane lining of the mouth and tongue.
Candidiasis - oral; Oral thrush; Fungal infection - mouth; Candide - oral
Causes, incidence, and 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.
Thrush appears as whitish, velvety lesions in the mouth and on the tongue. Underneath the whitish material, there is red tissue that may bleed easily. The lesions can slowly increase in number and size.
Signs and tests
Your doctor or dentist can almost always diagnose thrush by looking at your mouth and tongue. These fungal lesions have a distinct appearance. If not entirely clear, one of the following tests may be performed to look for the Candida organisms:
- Microscopic examination of mouth scrapings
- Culture of mouth lesions
For thrush in infants, treatment is often NOT necessary. It generally gets better on its own within 2 weeks.
If you develop a mild case of thrush after taking antibiotics, eating yogurt or taking over-the-counter acidophilus capsules can help.
Use a soft toothbrush and rinse your mouth with a diluted 3% hydrogen peroxide solution several times a day.
Good control of blood sugar levels in persons with diabetes may be all that is needed to clear a thrush infection.
Your doctor may prescribe an antifungal mouthwash (nystatin) or lozenges (clotrimazole) to suck on if you have a severe case of thrush or a weakened immune system. These products are usually used for 5 - 10 days. If they don't work, other medication may be prescribed.
If the infection has spread throughout your body or you have HIV/AIDS, stronger medications may be used, such as fluconazole (Diflucan) or ketoconazole (Nizoral).
Thrush in infants may be painful, but is rarely serious. Because of discomfort, it can interfere with eating. If it does not resolve on its own within 2 weeks, call your pediatrician.
In adults, thrush that occurs in the mouth can be cured. However, the long-term outlook is dependent on your immune status and the cause of the immune deficit.
If you have a weakened immune system (for example, if you are HIV-positive or receiving chemotherapy), Candida can spread throughout your body, causing infection in your esophagus (esophagitis), brain (meningitis), heart (endocarditis), joints (arthritis), or eyes (endophthalmitis).
Calling your health care provider
Call your doctor if:
- Your infant has had lesions in the mouth consistent with thrush for at least 2 weeks.
- Your infant is eating poorly due to the lesions.
- You are a teen or adult with lesions that are consistent with thrush.
- You have pain or difficulty swallowing.
- You have symptoms of thrush and you are HIV positive, receiving chemotherapy, or take medications to suppress your immune system.
If you have frequent outbreaks of thrush, your doctor may recommend taking antifungal medication on a regular basis to avoid recurrent infections.
If an infant with thrush is breastfeeding, talk to your doctor about ways to prevent future infections, such as an antifungal medication. Sterilize or discard any pacifiers. For bottle-fed babies with thrush, discard the nipples and buy new ones as the baby's mouth begins to clear.
To prevent spread of HIV infection, follow safe sex practices and universal precautions when working with blood products.
Kauffman CA. Candidiasis. In: Goldman L, Ausiello D, eds. Cecil Textbook of Medicine. 23rd ed. Philadelphia, Pa: Saunders; 2007:chap 359.
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.