Thrush (Candidiasis)


What Is It?

Thrush is the common name for a mouth infection caused by an overgrowth of the Candida fungus. This fungus normally lives in many people's mouths. Thrush is a surface infection. It can affect the corners of the mouth, the insides of the cheeks, the tongue, roof of the mouth (palate) and throat.

Thrush is common in babies. A newborn may acquire the Candida fungus during delivery, if its mother had an active yeast infection in the vagina. Symptoms of thrush usually follow within 7 to 10 days after birth. Babies with the infection may pass it on to their mothers while nursing. Then the mother and baby pass it back and forth. The mother may feel pain upon nursing and pain deep inside the breast. Nipples may be unusually red or sensitive. Tell your physician if you have these symptoms.

In older children or adults, thrush is triggered most often by:

  • Diseases or drugs that affect the immune system
  • Cancer chemotherapy
  • Steroid therapy
  • Treatment with antibiotics

Antibiotics trigger thrush by killing the mouth's normal population of bacteria. Once these normal bacteria are gone, Candida can grow without competition. People with dry mouth have less saliva and are more prone to developing thrush. Many medicines, both prescription and over-the-counter, can cause dry mouth. Tell your physician and dentist about of all the medicines you take. Be sure to include both prescription and over-the-counter medicines.

Certain people are more likely to get thrush. Examples include people who wear complete dentures, people with diabetes, and the elderly and debilitated. People who are malnourished have a higher risk of thrush. So do people with illnesses that weaken immune defenses, such as cancer or HIV infection.


The first symptoms may be a bad taste in the mouth and decreased taste sensation. Thrush causes white patches, with a texture similar to cottage cheese, inside the mouth. They are found most commonly on the tongue, roof of the mouth, back of the throat and corners of the mouth. If you try to scrape off the whitish surface of a patch, you will usually find a red, inflamed area underneath. It may bleed slightly. You also may have cracked, red, moist areas of skin at the corners of the mouth.

Sometimes thrush patches are painful, but often they are not. Infants who have painful patches may be fussy, irritable and feed poorly.


Your dentist or physician usually diagnoses thrush by looking in your mouth. He or she will try to scrape off any white patches with a tongue blade or gauze pad. If the diagnosis is in question, your physician or dentist also may send a sample of these scrapings to a laboratory for testing. In certain cases, a biopsy is needed. In this procedure, a small piece of skin is removed and examined in a laboratory.

In most patients, this is all that needs to be done for diagnosis. However, if you get thrush often or it doesn't go away, you may have an undiagnosed medical illness. Diabetes, cancer and HIV infection are all possible causes. In this case, blood tests or other types of tests may be needed. Your physician or dentist will ask about your history of these illnesses and about recent drug therapy.

Your physician or dentist also will ask about your recent use of antibiotics or medicines that suppress the immune system. Examples include steroids or cancer chemotherapy drugs. Your physician or dentist also can determine if you are taking any medicines that cause dry mouth.

Expected Duration

With proper medical treatment, most simple thrush infections can be cured in about 7 to 14 days.


You can help to prevent thrush. Use antibiotics only as prescribed by your doctor. See your dentist promptly for any mouth irritation or soreness around dentures. To prevent thrush in newborns, tell your doctor if you have any white, cheesy vaginal discharge while you are pregnant.

People with HIV or others who are taking drugs that suppress the immune system may have an even greater risk of thrush. Doctors may prescribe antifungal drugs, such as clotrimazole (Mycelex), to prevent thrush. However, there is some evidence that Candida fungi eventually become resistant to these drugs. Therefore, this preventive use is still controversial.


Doctors treat thrush with antifungal medicines such as:

  • Nystatin (Mycostatin, Nilstat)
  • Clotrimazole (Mycelex)
  • Ketoconazole (Nizoral)
  • Fluconazole (Diflucan)

For mild cases, a nystatin mouth rinse or a clotrimazole lozenge may be used. For more severe cases, ketoconazole or fluconazole may be taken once a day for 7 to 10 days. The corners of the mouth can be treated effectively with a nystatin ointment.

After successful treatment of thrush, your doctor may switch you from medicines that are suspected of causing significant dry mouth to medicines that are less drying. Only your doctor should change prescribed medicines that you are taking. Sometimes, medicines cannot be substituted for medical reasons. In this case, you should drink more water, and use mouth moisturizers and saliva replacements often.

When To Call A Professional

Call your physician or dentist whenever curdlike white patches appear inside your mouth or in the mouth of your infant. Call your pediatrician right away whenever any mouth irritation prevents your baby from feeding normally. Rarely, the fungus may affect the esophagus and cause problems with swallowing. If this happens, you should phone your dentist or physician. All patients with suppressed immune systems should get regular checkups for oral problems such as thrush.


In most otherwise healthy patients, a properly treated thrush infection goes away without permanently damaging the skin. The infection may not return as long as you stay healthy and well nourished. However, people with long-term illnesses or weakened immune systems may have frequent episodes of thrush. In some debilitated patients, the Candida fungus may even spread to the throat, causing Candida esophagitis, or to other parts of the body.

Additional Info

National Institute of Dental and Craniofacial Research
Bethesda, MD 20892-2190
Phone: 301-496-4261
Toll-Free: 1-866-232-4528
Fax: 301-480-4098

Centers for Disease Control and Prevention (CDC)
Oral Health Program
4770 Buford Highway, NE
MS F-10
Atlanta, GA 30341
Phone: 770-488-6054


© 2002- 2017 Aetna, Inc. All rights reserved.

This article is intended to promote understanding of and knowledge about general oral health topics. It is not intended to be a substitute for professional advice, diagnosis or treatment. Always seek the advice of your dentist or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment.

More Articles You May Like