Diagnosing vaginal thrush

Vaginal thrush can usually be easily diagnosed.

If you visit your GP because you think that you may have vaginal thrush they will ask you about:

  • your symptoms
  • whether you’ve had thrush before
  • whether you’ve already used any over-the-counter medications to treat thrush
  • whether you’re prone to developing thrush – for example, if you’re taking antibiotics for another condition

It is likely that you have thrush if you have the typical symptoms of vulval itching and a thick, creamy discharge. However, you may need to have further tests to be absolutely sure of the diagnosis.

Further tests

Your GP may want to carry out some further tests if:

  • you’ve already used anti-thrush treatment but it hasn’t worked 
  • the thrush keeps returning
  • your symptoms are particularly severe
  • you may have a sexually transmitted infection (STI)

Some possible tests are described below.

Vaginal swab

A vaginal swab is similar to a cotton bud. It is used to take a sample of the secretion from inside your vagina so that it can be analysed in a laboratory.

The results of the analysis will show whether you have a yeast infection or whether your symptoms are being caused by an STI, such as trichomoniasis.

A vaginal swab can also establish the type of fungus that is causing your thrush.

Blood test

You may have a blood test to check whether you have a condition that increases your risk of developing thrush.

For example, your GP may test the level of glucose in your blood if they think you might have diabetes.

If you have diabetes, you will probably have other symptoms such as an increased thirst and you may urinate more often.

pH level

Testing the pH (acid/alkaline balance) of your vagina may be recommended if the treatment for thrush hasn’t worked and it keeps returning.

To do this, a swab is taken from inside your vagina and wiped over a piece of specially treated paper. The paper will change colour depending on the pH level.

A pH level of 4-4.5 is normal. A pH above 4.5 may be a sign of a common vaginal infection called bacterial vaginosis.

Read about how thrush is treated.

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