There are several things that can increase your risk for getting thrush.
- Newborns and infants don't have fully developed immune systems, which increases their risk of developing infections, including thrush.
- Newborns are also in the process of developing a healthy balance of bacteria and fungi in their mouths. If this balance is upset, the child may develop thrush.
- Older adults, especially those who have serious health problems, are more likely to develop thrush, because their immune systems are likely to be weaker.
- The yeast that causes thrush can be spread by oral sex.
- Heavy smoking can lower the body's ability to fight off infections, making thrush more likely to develop.
- False teeth (dentures), braces, or a retainer that irritates the mouth make it hard to keep the mouth clean and can increase your risk for thrush. An unclean mouth is more likely to develop thrush than is a clean mouth.
- People with a weakened immune system, such as those who have diabetes or human immunodeficiency virus (HIV) or who are having chemotherapy treatments, have an increased risk for thrush.
- Having a dry mouth (xerostomia) can lead to thrush. Dry mouth can result from overuse of mouthwashes or from certain conditions such as Sjögren's syndrome.
- Pregnancy increases your risk for thrush. Hormone changes during pregnancy can lead to thrush by changing the balance of bacteria in the mouth.
Medicines that can cause thrush yeast to grow uncontrolled include:
- Antibiotics, especially those that kill a wide range of organisms (broad-spectrum antibiotics), such as tetracycline.
- Birth control pills (oral contraceptives).
- Medicines that weaken the body's immune system, such as corticosteroids.
Exposure over time to certain environmental chemicals, such as benzene and some pesticides, can weaken the body's immune system, increasing your risk for infections, including thrush.