Understanding Oral Thrush
Oral thrush is a fungal infection in the mouth. It is common in people who wear dentures, use inhalers or have a weak immune system. It can be treated.
What is oral thrush?
Oral thrush (oral candidiasis) is an infection in the mouth. It is caused by a fungus called Candida albicans.
Small amounts of this fungus live in the mouth naturally. In some conditions it can grow too much and cause an infection.
Thrush can affect people of any age. It is most common in:
- babies and young children
- older adults, mainly those who wear dentures
- people with a weak immune system
- people who use steroid inhalers (such as inhalers for asthma)
- people with a dry mouth
- people who take antibiotics for a long time
In healthy adults, oral thrush is not passed on through normal contact. It is not a sexually transmitted infection.
What causes oral thrush?
Some things let Candida grow too much:
- Steroid inhalers. Inhaled steroids (used for asthma or COPD) can leave a residue in the mouth. This helps the fungus grow. Rinsing your mouth with water after using your inhaler greatly lowers this risk.
- Antibiotics. These kill helpful bacteria in the mouth that normally keep Candida in check.
- Dry mouth. Saliva helps fight fungus. Less saliva lets Candida thrive.
- Dentures, mainly if they are not cleaned well or are worn while you sleep. Dentures that do not fit well trap the fungus under the plate.
- A weak immune system. This can be due to conditions such as HIV, diabetes, cancer treatment or long-term steroid use.
- Smoking. This changes the mouth and raises the risk.
Signs and symptoms
Thrush can look and feel different depending on the type and how bad it is:
- White or cream patches on the tongue, inside the cheeks, on the roof of the mouth or in the throat. You can often wipe these off. This may leave a red or bleeding area underneath.
- Redness and soreness in the mouth, often under dentures (called denture stomatitis)
- A burning or sore feeling in the mouth or throat
- An unpleasant taste, or a change in taste
- Cracks and redness at the corners of the mouth (angular cheilitis, often linked to thrush)
- Finding it hard to eat or swallow, in more severe cases
How is oral thrush treated?
Oral thrush is very treatable. Your dentist or doctor will usually prescribe an antifungal medicine:
- Miconazole oral gel. This antifungal gel goes straight onto the sore areas in your mouth. It is the most common first treatment. Put it on with a clean finger after meals. Keep it on the sore area as long as you can before you swallow. Important: miconazole interacts significantly with warfarin (a blood-thinning medicine). It can raise the risk of bleeding. Tell your dental team or doctor if you take warfarin or any other blood thinner (anticoagulant) before you are prescribed miconazole.
- Babies: Miconazole gel is not suitable for babies under 4 months old because of the risk of choking. For older babies, use small amounts and never put gel at the back of the mouth. Always ask a pharmacist, GP or dentist before treating a baby.
- Nystatin liquid (suspension). You hold this antifungal liquid in your mouth, then swallow it. It is used when miconazole cannot be used, for example if you take warfarin or some other medicines.
- Fluconazole tablets. You swallow this antifungal and it works through the whole body. It is used for more severe infections, or ones that keep going.
Take your antifungal medicine exactly as your dentist or doctor prescribed. Take it for the full number of days they advised, even if you feel better quickly. Do not stop early unless your dental team or doctor tells you to. Stopping without their advice can let the infection come back.
What you can do at home
Good mouth care and a few simple steps can stop thrush coming back:
- Rinse your mouth with water and spit it out every time you use a steroid inhaler. This works very well to prevent thrush from inhalers.
- Ask your GP or asthma nurse about using a spacer with your inhaler. A spacer greatly reduces the amount of steroid left in your mouth and throat.
- If you wear dentures, take them out at night. Do not sleep in your dentures.
- Clean your dentures well with a denture brush and denture cleaner.
- Soak your dentures overnight in a denture cleaning solution.
- Clean your tongue gently when you brush your teeth.
- Avoid sugary foods and drinks. Candida thrives on sugar.
- Drink plenty of water. Good saliva flow helps stop the fungus growing too much.
- If you have a dry mouth, ask your dental team about dry mouth products that contain antifungal agents.
When to see your dental team or doctor
See your dental team or doctor if:
- you have white patches in your mouth that have not cleared within 2 weeks of treatment, or that keep coming back
- you are not sure if the patches are thrush. Not all white patches in the mouth are thrush, and some need more tests.
- the infection is spreading, or you find it hard to swallow
- you are in a high-risk group (a weak immune system, or diabetes that is not well controlled) and you get symptoms
Important: a dental or medical professional must always check a white patch in the mouth that does not wipe off, does not clear with antifungal treatment and lasts more than 3 weeks. It is not likely to be thrush and needs more tests.
This leaflet is for general information only and does not replace professional dental advice. Your dental team will discuss your individual circumstances and any risks and treatment specific to you. Treatment outcomes vary between patients depending on individual circumstances.
Sources
- Oral thrush (mouth thrush). NHS website (nhs.uk), reviewed October 2026.
- Drug Prescribing for Dentistry, 3rd edition; online version updated for BNF 91. Scottish Dental Clinical Effectiveness Programme (SDCEP), 2016, updated 2026.
Links checked 18 October 2026.
Embed this leaflet free on your website
Copy and paste this code to add this leaflet to your practice website. Free to embed — please keep the nosht.io credit.
<iframe src="https://nosht.io/embed/leaflet/understanding-oral-thrush" title="Understanding Oral Thrush — patient leaflet by nosht.io" loading="lazy" style="width:100%;min-height:4300px;border:0"></iframe>
<script>(function(){if(window.__noshtEmbedResize)return;window.__noshtEmbedResize=1;window.addEventListener("message",function(e){var d=e.data;if(e.origin!=="https://nosht.io"||!d||d.type!=="nosht:embed-height"||typeof d.height!=="number")return;var f=document.getElementsByTagName("iframe");for(var i=0;i<f.length;i++){if(f[i].contentWindow===e.source){f[i].style.height=Math.min(Math.max(d.height,200),20000)+"px";}}});})();</script>
<p style="font:12px/1.4 sans-serif;margin:4px 0 0">Patient leaflet: <a href="https://nosht.io/leaflets/understanding-oral-thrush/">Understanding Oral Thrush</a> by Nosht</p>Sizing. The iframe is fluid-width with no fixed height. Its min-height of 4,300 px is this leaflet’s own measured height in a phone-width (390 px) column, so nothing is cut off on a mobile. In a wide article column (768 px) the same leaflet is about 3,300 px tall — lower the number to that if your layout is wide. A narrower column simply scrolls inside the frame; no content is ever lost.
Related leaflets
Learn more about dental documentation on our blog or see Nosht pricing.