Yeasts are single-cell organisms that belong to the fungus kingdom. Of the 1,500 recorded species of yeasts today, Candida is the most notable type because it is responsible for candidiasis, commonly known as yeast infection.1
Candida is harmless and it can live on your skin and digestive tract. However, it can grow at an alarming rate and cause itching, swelling and irritation to the skin, mouth lining, anus and genital area. In rare cases, Candida can cause invasive candidiasis, a condition that affects your internal organs.
The most common Candida (C.) strains responsible for candidiasis are:2
• C. albicans
• C. tropicalis
• C. parapslosis
• C. glabrata
• C. guilliermondii
Factors That Can Cause Vaginal Candidiasis
Candida normally lives in small, harmless numbers in your vagina,4 but medications such as antibiotics can lower the probiotics (the good bacteria) in your vagina, causing yeast to spread.5 Corticosteroids, a type of drug used to treat symptoms of various diseases by lowering your immune system, may also cause yeast to grow.
Diabetes has been shown to be a factor, especially if your blood sugar levels are high all the time, because the fuel source of yeast is sugar. Obesity, which is closely related to diabetes, may also cause candidiasis.6
Other known factors include hyperestrogenemia, a condition that indicates high levels of estrogen during pregnancy, hormonal imbalance near your menstrual cycle and use of high-dose birth control pills.
Clothing may also play a role in the formation of vaginal yeast infection. Wearing tight-fitting, nonabsorbent pants that hold in warmth and moisture can create the perfect environment for yeast to grow and eventually spread.7
Sexual Activity May Lead to Yeast Infection
While not an STI, it is important to note that candidiasis can increase your risk for getting one. According to Everyday Health, women who contracted HIV were more likely to have a history of yeast infection.9
One probable cause is the intense scratching of your vaginal area to relieve itching. This can accidentally create microscopic tears in your skin, allowing STI-causing microorganisms to enter your bloodstream during sexual intercourse. For men, there's a chance they may get yeast infection from an infected partner. Main indicators of penile candidiasis include penile discharge and rashes. If other symptoms start appearing, such as a burning feeling or itching, a visit to the doctor is strongly advised.
It's best to avoid or at the very least, reduce sexual activity for both genders until the infection has been cured. Following your doctor's advice can help prevent infections from recurring and getting an STI.