Vaginal thrush is a yeast infection that is usually caused by a type of fungus that lives naturally in the vagina and skin. Over 90% of cases of thrush are caused by Candida albicans. It’s believed that a change in the natural balance of the vagina leads to the growth of Candida and causes the symptoms of thrush.
This can be a chemical change – for example, when you take antibiotics – or it can be a hormonal change – such as during pregnancy.
Your risk of developing thrush increases if you:
- take antibiotics
- are pregnant
- have poorly controlled diabetes
- have a weakened immune system
Thrush happens in about a third of women who take antibiotics, because antibiotics get rid of the friendly bacteria in the vagina that limit the excessive growth of fungi. Any type of antibiotic can increase your chances of developing thrush, but for you to develop the yeast infection, the Candida fungus must already be present in your vagina.
If you’re pregnant, changes in the levels of female hormones, such as oestrogen, increase your chances of developing thrush and make it more likely to keep coming back.
If you have poorly controlled diabetes – when your blood glucose levels go up and down, rather than being stable – you are more likely to develop thrush.
4.Weakened immune system
Your risk of developing thrush is also increased if your immune system is weakened – for example, when you have an immunosuppressive condition, such as HIV or AIDS, or if you are having chemotherapy.
This is because in these circumstances your immune system, which usually fights off infection, is unable to control the spread of the Candida fungus.
Myths and facts
The following have, rightly or wrongly, been suggested as potential causes of thrush:
It is possible that some contraceptives, particularly the combined pill, can increase your risk of getting thrush. Other types of progesterone contraception that stop ovulation may reduce your risk of getting thrush.
However, there’s hardly any evidence to support this.
- Tight-fitting clothing
Wearing tight-fitting clothing may increase your risk of developing thrush. However, the evidence to support this claim is weak.
- Female hygiene
There’s also little evidence to suggest that sanitary towels, tampons or vaginal douching increase your chances of getting thrush.