What Happens

Most cases of thrush are mild and clear up with the use of an antifungal mouth rinse or lozenges. Very mild cases of thrush may clear up without medical treatment. It usually takes about 14 days of treatment with an oral antifungal medicine to cure more severe thrush infections. In some cases, thrush may last several weeks even with treatment.

If thrush goes untreated and does not go away by itself, it can spread to other parts of the body.

• Thrush can spread to the throat (esophagus), the vagina, or the skin. It rarely spreads to other organs of the body.
• Infants can get a diaper rash because the yeast that causes thrush is in the infant's stool.

Thrush is more likely to recur in:

• People who use inhaled corticosteroids to treat asthma.
• People who take antibiotic medicines for a long time.
• People who have false teeth.
• People who have a weakened immune system.
• Children who put objects contaminated with the thrush-causing yeast into their mouths.

Complications

Complications related to thrush are rare in healthy people but may include:

• Poor nutrition for infants who have trouble eating because of thrush.
• Infection of the throat.

What Increases Your Risk

There are several things that can increase your risk for getting thrush.

Age

• Newborns and infants don't have fully developed immune systems, which increases their risk of developing infections, including thrush.
• Newborns are also in the process of developing a healthy balance of bacteria and fungi in their mouths. If this balance is upset, the child may develop thrush.
• Older adults, especially those who have serious health problems, are more likely to develop thrush, because their immune systems are likely to be weaker.

Behavior

• The yeast that causes thrush can be spread by oral sex.
• Heavy smoking can lower the body's ability to fight off infections, making thrush more likely to develop.

Other conditions

• False teeth (dentures), braces, or a retainer that irritates the mouth make it hard to keep the mouth clean and can increase your risk for thrush. An unclean mouth is more likely to develop thrush than is a clean mouth.
• People with a weakened immune system, such as those who have diabetes or human immunodeficiency virus (HIV) or who are having chemotherapy treatments, have an increased risk for thrush.

Medications

Medicines that can let the thrush yeast grow uncontrolled include:

• Antibiotics, especially those that kill a wide range of organisms (broad-spectrum antibiotics), such as tetracycline.
• Birth control pills (oral contraceptives).
• Medicines that weaken the body's immune system, such as corticosteroids.

Environment

Exposure over time to certain environmental chemicals, such as benzene and some pesticides, can weaken the body's immune system, increasing your risk for infections, including thrush.