What Causes Thrush? Common Triggers, Risk Factors and Treatments

Here’s everything you need to know about why you get thrush and what to do about it.

Published: Monday 04 April 2022

What causes Thrush?

So, What Causes Thrush?

The culprit of thrush infections is the candida fungus, a yeast found in the gastrointestinal tract of about 30-45% of the population.[1] In healthy people the candida fungus is usually harmless but, given the right circumstances, it can overgrow and lead to a yeast infection. Thrush can appear in the mouth (oral thrush) or in/on the vagina or penis (genital thrush).[2]

Thrush Triggers

The candida fungus in the gut is usually kept in check by other microorganisms and bacteria that limit its growth. If the balance is disturbed in your gut microbiota (the complex system of microorganisms in your digestive tract), the candida fungus can thrive and cause thrush.[3]

Some of the things that can help yeast to flourish and cause this gut disturbance include:

  • Medications such as antibiotics, corticosteroids, or birth control pills
  • Illnesses
  • Stress
  • Products that irritate the skin, such as perfumed skin products and bubble baths
  • Finishing up a course of antibiotic treatment

It’s worth noting that whilst you can pass on thrush through sexual intercourse, this is uncommon. Thrush is NOT a sexually transmitted infection (STI) and you can develop thrush seemingly out of the blue.

Thrush Risk Factors

You are more at risk of getting thrush if you:

  • Are pregnant
  • Have poorly-controlled diabetes
  • Are obese
  • Are having sex whilst on your period
  • Have a weakened immune system, such as if you have HIV or are undergoing chemotherapy
  • Smoke (oral thrush)
  • Wear dentures that don’t fit correctly (oral thrush)
  • Use asthma inhalers (oral thrush)

How to Treat Thrush

You can prevent developing genital thrush by following a healthy lifestyle, using non-perfumed pH-balanced cleaning products like the Femfresh Wash and Femfresh Wipes to avoid irritation, and giving your genital area ample opportunity to dry after washing. For oral thrush, make sure to practise good dental hygiene, sterilise babies’ bottles and dummies regularly, don’t smoke and clean your dentures thoroughly.

But with thrush affecting so many of us, avoiding it all together is a tall order. Thankfully thrush is easily and quickly treatable with antifungal medication, containing either fluconazole, clotrimazole or miconazole.


As the quickest method of clearing a genital thrush infection, Fluconazole is a convenient oral capsule treatment that requires just one capsule to be taken. The active ingredient fluconazole stops the candida fungi from producing ergosterol, a component necessary for their cell membranes, and thus controls the spread in as little as two days.


This powerful antifungal medication can be found in the Canesten line of genital thrush treatments, which are popular and effective methods of managing the infection. Canesten Internal Cream and Canesten Pessary are 2 different applications for internally inserting the medication into the vagina, targeting the infection at the source. Canesten External 1% and Canesten External 2% are creams that also contain clotrimazole but more specifically help relieve the external symptoms like itching, redness and irritation typically associated with genital thrush.

You can benefit from a combination of both fluconazole and clotrimazole for relief from both the infection and its symptoms by using the Canesten Thrush Duo treatment, featuring the external 2% cream and a fluconazole tablet.


For those suffering from oral thrush, miconazole is a great option to clear the infection, working by making holes in the candida fungus cell membranes and managing overgrowth. Daktarin Oral Gel is a popular topical treatment able to clear the infection in a week.

Other Thrush Resources

Wondering what a thrush infection looks like? Why not check out our article where we answer the most common thrush questions.

You can compare the features of our thrush treatments side-by-side in our complete guide to thrush treatments.

Keep getting thrush and are not sure why? Our guide to recurring thrush has everything to know about more chronic thrush infections and what you can do about it.

Toby Watson

Written by: Toby Watson

Pharmica Medical Writer

Toby (BSc) is an experienced medical writer, producing educational articles on many areas of health including sexual health, fitness, nutrition and mental health.

He particularly enjoys debunking misconceptions around heath conditions and their treatments, researching each topic in detail and writing easily-accessible content.

Find out more about how we ensure the accuracy of our content with our content guidelines.

Video Guide: Fluconazole (Thrush Treatment)
Video Guide: Fluconazole (Thrush Treatment)