Thrush, vaginal

Vaginal thrush is a fungal infection that causes irritation and swelling of the vagina and vulva (a woman’s external sexual organs).

Thrush is also known by a number of names including:

• candida,
• vulvovaginal candidiasis,
• vulvovaginal candidosis, and
• vaginal yeast infection.

Thrush is most commonly caused by a type of fungus known as Candida albicans. The Candida species of fungus is found naturally in the vagina, and is usually harmless. However, if the conditions in the vagina change, Candida albicans can cause the symptoms of thrush.

It is not known exactly how changes that occur in the vagina trigger thrush, but it may be due to a hormone (chemical) imbalance. In most cases, the cause of the hormonal changes is unknown. However, some possible risk factors have been identified, such as taking antibiotics (medicines used to treat infections caused by bacteria). 

How common is vaginal thrush?

Up to 75% of women will experience thrush at some point in their lives, and up to half of these will experience thrush more than once. Thrush most commonly affects women in their twenties and thirties, and those who are pregnant.

Thrush is less common in girls who have not yet started their periods, and women who have started the menopause (when a woman’s periods stop).

It is not known what makes some women more prone to thrush than others, but women with poorly controlled diabetes, or a seriously damaged immune system, have an increased risk of developing the condition.

Outlook

Thrush can be treated with antifungal medication taken orally (by mouth), or as an intravaginal pessarie (a tablet that is inserted into the vagina). Both methods effectively treat thrush in around 80% of cases.

Around 5% of women may experience recurrent episodes of thrush (four or more episodes in one year), and 1% of women may have thrush almost constantly.  Maintenance therapy, when antifungal medications are taken for up to six months, may reduce the reoccurrence of thrush.