Thrush or oral candidiasis is caused by a fungus called Candida albicans. Small amounts of Candida live in the mouth, but the immune system of a healthy person prevents it from growing, according to MedlinePlus. Symptoms of thrush include creamy white lesions on the tongue and mouth, bleeding and pain, notes The Merck Manual. The condition usually clears in seven to 10 days when treated with an antifungal medication. Patients taking certain medications or suffering from conditions that weaken the immune system are at risk for developing thrush, as are infants and the elderly.
Weakened Immune System
A healthy person's immune system fights off Candida and other organisms that normally inhabit the body, notes MedlinePlus. Diseases that weaken the immune system, however, allow Candida to accumulate in the mouth. In fact, the appearance of thrush in a patient with a compromised immune system, such as those with human immunodeficiency virus, may be a signal that the underlying disease is worsening. Elderly patients and those in generally poor health often develop thrush as well.
Sugar
Candida feeds on sugar, so diabetics with high levels of sugar in their saliva are more likely to develop thrush, according to MedlinePlus. Non-diabetics who eat excessive amounts of sugar and heavy users of alcohol, which is converted to sugar in the body, are also at risk for developing thrush, according to the ProjectInform website.
Treatment for Other Conditions
Taking certain medications can provide an environment that allows Candida to flourish in the mouth. Antibiotics taken in high doses or on a long-term basis can kill the normal flora in the body, allowing Candida to grow, reports The Merck Manual. Steroid medications such as prednisone, as well as chemotherapy and radiation for cancer, weaken the patient's immune system, predisposing the patient to developing thrush, notes MedlinePlus.
Mother to Child
Candida causes vaginal yeast infections as well as thrush. A pregnant woman with a vaginal yeast infection can pass the fungus to her baby during childbirth, resulting in oral thrush in the newborn, reports the Mayo Clinic. A nursing mother may also pass a Candida infection from the breast to the child. Thrush is common in infants, according to MedlinePlus, and is not a cause for concern unless it lasts for several weeks. The condition can be painful in infants, however, and can interfere with feeding.
