Candida is a kind of yeast that's naturally present in the human body. Normal amounts of candida shouldn't cause any problems in healthy individuals. But when the candida population inside the body—the throat, mouth, gastrointestinal tract or gut, and vagina—or on the skin spirals out of control, that's when the trouble starts.

The accumulation of C. albicans on the mouth's lining gives rise to a condition called oral candidiasis or oral thrush. The tell-tale signs include creamy white lesions on the inner cheeks or on the tongue, irritation that may make it difficult to chew or swallow, and in some cases, loss of taste.

C. albicans coexists with bacteria such as lactobacillus in the vagina. However, an overgrowth of the fungus results in vulvovaginal candidiasis or yeast infection. In addition to vaginal discharges, yeast infections can also cause itching and irritation, rashes, and a burning sensation while urinating or during sexual intercourse. Most yeast infections occur in women, but men can contract the ailment too. Called balanitis, it's characterized by inflammation of the glans, itching and redness, and shiny, white discolorations on the penis.

Too much candida in the small intestine can lead to a slew of gastrointestinal (GI) discomforts including diarrhea, indigestion, bloating, and gas.

Invasive candidiasis is less common than thrush or yeast infections, but it can have much more sinister health consequences. When candida enters the bloodstream, it can cause candidemia, which can be fatal. Invasive candidiasis can also have adverse effects on major organs like the heart and brain.