Certain germs normally live in our bodies. This includes bacteria and fungi. While most germs are harmless, some can cause infection under certain conditions.
Thrush occurs in children and adults when conditions permit too much growth of a fungus called candida in your mouth. A small amount of this fungus normally lives in your mouth. It is most often kept in check by your immune system and other germs that also live in your mouth.
When your immune system is weak or when normal bacteria die, too much of the fungus can grow.
You are more likely to get thrush if:
You are in poor health.
You are very old. Young babies are also more likely to develop thrush.
You have symptoms of thrush and you are HIV positive, receiving chemotherapy, or you take medicines to suppress your immune system.
If you get thrush often, your provider may recommend taking antifungal medicine on a regular basis to keep thrush from coming back.
If you have diabetes mellitus, you can help prevent thrush by keeping good control of your blood sugar levels.
Edwards JE Jr. Candida species. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 258.
Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.