Oral thrush infections are caused by an increase in the levels of Candida albicans fungi that are naturally present in the mouth. This increase may result from:
- the immune system being weakened (immunodeficiency)
- an underlying health condition, such as cancer or HIV
- smoking
- taking corticosteroid medication
- certain medications that reduce the amount of saliva produced
- an injury in the mouth
Corticosteroids can be used to reduce inflammation (swelling) and to treat a variety of conditions such as:
- some types of cancer
- arthritis, which is a condition that causes inflammation of the bones and joints
- eczema, which is a long-term skin condition that causes itchy, dry and red cracked skin
- asthma, which is a long-term condition that causes the airways of the lungs to become inflamed and swollen
Inhaled corticosteroids are often used to treat asthma. The medicine is breathed in through an inhaler, which allows it to be passed directly into the lungs. Although inhaled corticosteroids cause fewer side effects than other forms of treatment, they can change the acidity levels in the mouth, killing healthy bacteria and causing an imbalance that makes oral thrush more likely to develop.
Risk factors
You are at an increased risk of developing oral thrush if:
- you have diabetes
- you are a certain age (oral thrush is more common in infants and elderly people)
- you have high blood sugar levels
- you wear dentures that are poorly fitted or not cleaned regularly
- you often take antibiotics (medication used to fight infections)
- you have an iron deficiency or B-vitamin deficiency
- you are having treatment for cancer such as chemotherapy or radiotherapy
