Several factors can promote the overgrowth of Candida albicans (C. albicans), the most common cause of genital candidiasis (yeast infection), in the vagina and penis. For instance, yeast infections are very common among pregnant women because the hormonal changes associated with pregnancy may increase the amount of sugar in the vaginal secretions. This in turn provides nourishment to the yeast.  

Similarly, people with uncontrolled diabetes have an increased risk of developing yeast infections because elevated blood sugar levels impair immune function. When blood sugar levels rise, body secretions contain increased amounts of sugar. In addition, body tissues stop functioning properly. Therefore, normal bodily defenses against intrusion by yeast and other outside substances are diminished.

Older girls may also develop yeast infections, often just before they get their menstrual periods. This is due to the hormonal changes in the body that accompany menstruation.

Certain medications can increase the risk of developing a yeast infection. Oral contraceptives (birth control pills), hormone therapy and corticosteroids can alter the hormone balance in women and increase the growth of yeast. Antibiotics are also considered a risk factor for yeast infections. Antibiotics can kill the “good” bacteria that live in the body. These bacteria normally keep the Candida in the genitalia in check. When they are destroyed, Candida can grow and cause a yeast infection.

Tight fitting clothing, especially undergarments, and synthetic materials can also increase yeast infections. These items can trap heat and moisture and create an optimal environment for the growth of Candida. Damp or wet clothing may contribute to the growth of organisms as well. Experts often recommend cotton undergarments.

Research has indicated that the use of irritating soaps, deodorants, douches and sprays may contribute to yeast infections. The products may change the alkaline levels in the genital area and promote yeast growth. Deodorant tampons may be a risk factor for women, as well as sanitary pads and panty liners. These items can trap moisture in the genital area and promote bacteria growth. Some studies suggest that oral sexual intercourse may also increase the risk of developing genital candidiasis.

People with genital candidiasis can sometimes transmit a yeast infection through sexual intercourse. In addition, yeast infections are more common in men who have not been circumcised.  

Other risk factors for yeast infections include:

• Weakened immune system
• Excessive alcohol use
• Use of hot tubs and saunas
• Stress from poor diet, lack of sleep or illness