Oral candidiasis (thrush)

November 2005     View PDF     En español

Cause

Oral candidiasis is caused by the fungus called Candida . Everyone has small quantities of the fungus in the mouth, vagina, digestive tract and skin. In healthy persons, “friendly” bacteria and the immune system prevent the fungus from causing disease. However, a damaged or weakened immune system, as can be the case in HIV disease, makes it easier for Candida to grow and cause disease.

Certain drugs can alter the natural organisms in the mouth, which can then promote the growth of Candida . These include the extended use of antibiotics, steroids and oral contraceptives with a high estrogen content. Other factors that may stimulate Candida growth include: diabetes, pregnancy, iron, folate, vitamin B12 or zinc deficiency and using antihistamines. Factors that may weaken the immune system—from cancer chemotherapy to stress and depression—can also cause candidiasis.