Thrush is caused by forms of a fungus called Candida. This organism lives in your mouth and is usually kept in check by healthy organisms that also live there. However, when your resistance to infection is low, the fungus can grow, leading to lesions in your mouth and on your tongue.

The following can lessen your resistance to infection and increase your chances of getting thrush:

• Taking antibiotics or steroid medications
• Having 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
• Having diabetes

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.

Thrush appears as whitish, velvety lesions in the mouth and on the tongue. Underneath the whitish material, there is red tissue that may bleed. The lesions can slowly increase in number and size.

If you are immunocompromised (for example, you are HIV positive or receiving chemotherapy), the infection can spread to other organs, such as the esophagus (causing pain with swallowing), or throughout your body, which can be deadly.

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 resolves on its own within two weeks.

There are two goals when treating oral thrush in adults. The first is to improve your immune system's ability to function. For example, in diabetics, good control of diabetes may be enough to clear the infection without other treatment.

The second is to directly treat the infection. For this purpose, your doctor may prescribe an antifungal mouthwash or lozenges to suck on. These 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 ketoconazole (Nizoral) or fluconazole (Diflucan).

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.

Candida can spread throughout your body, causing infection in your esophagus (esophagitis), brain (meningitis), heart (endocarditis), joints (arthritis), or eyes (endophthalmitis).

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.

Goldman L, Ausiello D, eds. Cecil Textbook of Medicine. 22 ed. Philadelphia, Pa: Saunders; 2004.

Marx JA, Hockberger RS, Walls RM, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 5th ed. St. Louis, MO: Mosby; 2002.

Mandell GL, Bennett JE, Dolin R, eds. Principles of Infectious Diseases. 5th ed. New York, NY: Churchill Livingstone, 2000.