Oral thrush
Introduction
Oral thrush, also known as oral candidiasis, is a yeast infection in the mouth caused by a fungus called candida albicans. It is not contagious, which means it cannot be passed on to others.
As well as oral thrush that occurs in the mouth, it is also possible to get other types of thrush in other parts of the body, such as:
- inside the vagina (vaginal thrush)
- the nappy area of babies
- the folds of skin overlapping the nail (cuticles)
- the head of the penis
See the Health topic about Thrush, men for more information about fungal infection of the head of the penis.
How common is oral thrush?
Oral thrush most commonly affects certain groups of people. It often affects people who wear dentures because they may have difficulties keeping their mouth clean. Around 7 in 10 people who wear dentures will develop oral thrush at some stage.
Oral thrush may also occur in people with a weakened immune system, such as those with HIV or AIDS. About 9 out of 10 people with AIDS have oral thrush, which can often be severe.
Oral thrush is also common in people with type 1 diabetes and type 2 diabetes. Diabetes is a long-term condition caused by too much glucose in the blood. A recent study has shown that oral thrush is five times more common in people with severe insulin-dependent diabetes (type 1) than the population at large.
Oral thrush can sometimes affect healthy newborn babies. It can be passed on from mother to baby during labour if the mother has a yeast infection in her vagina. It can also be passed on through breastfeeding if a yeast infection is present. See the Health topic about Oral thrush in babies for more information.
Outlook
Left untreated, oral thrush can cause soreness and discomfort in the mouth. However, the condition can usually be successfully treated with antifungal medicines. See Oral thrush in adults - treatment for more information.
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Symptoms
The symptoms of oral thrush can include:
- sore, white patches (plaques) in the mouth that can be wiped off
- a painful, burning sensation on the tongue
- an unpleasant taste in the mouth that can be bitter or salty
- redness and soreness on the inside of the mouth
- cracks at the corners of the mouth (angular cheilitis)
- difficulty swallowing
Dentures
If you wear dentures and you have oral thrush, you may develop sore, red areas in your mouth where the dentures have been. This is known as denture stomatitis and it can make wearing dentures uncomfortable.
When to seek medical advice
You should seek medical advice from your GP if you have any of the symptoms of oral thrush. It is important that oral thrush is treated quickly because if it is left untreated, the symptoms will persist and your mouth will continue to be uncomfortable.
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Causes
Oral thrush infections are caused by increase in the levels of Candida albicans fungi that are naturally present in the mouth. This increase may result from:
- the immune system being weakened (immunodeficiency)
- an underlying health condition, such as cancer or HIV
- smoking
- taking corticosteroid medication
- certain medications that reduce the amount of saliva produced
- an injury in the mouth
Corticosteroids can be used to reduce inflammation (swelling) and to treat a variety of conditions such as:
- some types of cancer
- arthritis, which is a condition that causes inflammation of the bones and joints
- eczema, which is a long-term skin condition that causes itchy, dry and red cracked skin
- asthma, which is a long-term condition that causes the airways of the lungs to become inflamed and swollen
Inhaled corticosteroids are often used to treat asthma. The medicine is breathed in through an inhaler, which allows it to be passed directly into the lungs. Although inhaled corticosteroids cause fewer side effects than other forms of treatment, they can change the acidity levels in the mouth, killing healthy bacteria and causing an imbalance that makes oral thrush more likely to develop.
Risk factors
You are at an increased risk of developing oral thrush if:
- you have diabetes
- you are a certain age (oral thrush is more common in infants and elderly people)
- you have high blood sugar levels
- you wear dentures that are poorly fitted or not cleaned regularly
- you often take antibiotics (medication used to fight infections)
- you have an iron deficiency or B-vitamin deficiency
- you are having treatment for cancer such as chemotherapy or radiotherapy
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Diagnosis
In most cases, your GP will be able to diagnose oral thrush simply by examining the white patches in your mouth. However, some tests may also be used to confirm the diagnosis.
Biopsy
A biopsy may be used to confirm a diagnosis of oral thrush. This involves taking a sample of the white patches in your mouth to check for the candida fungus under a microscope.
The sample may be stained with a type of dye known as a periodic acid-Schiff (PAS). Your GP may also take a swab from the affected area to monitor how the fungus grows over a period of several days.
Blood test
When investigating a case of oral thrush, your GP may recommend that you have a blood test. This is because oral thrush is sometimes associated with other conditions, such as diabetes and nutritional deficiencies.
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Treatment
Oral thrush can be successfully treated using antifungal medicines.
Antifungal treatments are available in the following forms:
- tablets
- lozenges
- powders
- creams
- rinses
Rinses are useful for people with a dry mouth who are unable to swallow antifungal tablets.
Antifungal medicines that can be used to treat oral thrush include:
- fluconazole
- itraconazole
- nystatin
- clotrimazole
- miconazole
- econazole
- ketoconazole
If you are taking certain antibiotics or corticosteroids that are thought to be causing your oral thrush, the medicine may need to be changed or the dosage reduced.
Some antifungal medications should not be used if you are pregnant, breastfeeding or taking other medications. Always seek advice from your GP or pharmacist before taking antifungal medicines.
Side effects
Possible side effects of antifungal medicines include:
- nausea (feeling sick)
- tummy pain
- diarrhoea
- headache
- indigestion
If you wear dentures, an antifungal cream can be applied to the affected area of the roof of the mouth and to the bottom of the dentures. Antifungal lozenges are also effective.
If the underlying cause of your oral thrush cannot be cured, you may need to continue taking antifungal treatment for a longer period of time.
See the Health topic about Antifungal medicines for more information about this type of treatment.
Oral thrush and HIV or AIDS
If you have HIV or AIDS and you develop oral thrush, this may be treated slightly differently. See the links below for more information.
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Prevention
The risk of getting oral thrush can be reduced by following the advice outlined below.
Oral hygiene
Your chances of getting oral thrush are reduced if you keep your mouth clean and healthy. You can do this by:
- rinsing your mouth after meals
- visiting your dentist regularly for check-ups
- eating a healthy balanced diet with no more than the recommended amount of sugar
- keeping your dentures clean
- brushing your teeth twice a day with a toothpaste that contains fluoride
- flossing regularly
- using a mouthwash as part of your routine
Denture hygiene
If you wear dentures it is important to clean them regularly to help prevent yeast from growing.
Your dentures should be removed and cleaned every night before you go to bed. They can be cleaned by brushing them with warm, soapy water and scrubbed with a nailbrush on the non-polished side of the dentures.
Dentures can then be soaked in any liquid that can be used to sterilize babies' bottles. However, products containing bleach should not be used on dentures that contain metal.
You should visit your dentist to correct dentures that do not fit properly. This can also reduce the risk of oral thrush and soreness underneath the dentures.
Speak to your dentist for further advice about how to clean your dentures.
Smoking
Smoking encourages the yeast in your mouth to grow and increases your chance of getting oral thrush. Contact the NHS Smoking helpline or speak to your GP if you want to give up smoking.
The NHS Smoking Helpline also offers advice and encouragement to help you give up smoking. You can phone the helpline (0800 169 0 169) or visit the Stop Smoking Wales website. Several treatments are available to increase your chance of quitting successfully, the helpline can provide you with local support groups and one-to-one counsellors.
The Health topic about Quitting smoking also has information and advice about giving up smoking.
Corticosteroids
If you use inhaled corticosteroids as part of your asthma treatment, you can help prevent oral thrush by:
- rinsing your mouth with water after using your inhaler
- developing a good technique when you inhale corticosteroids by using a spacer
A spacer is a small device that looks like a plastic tube. It is attached to your inhaler and can help to get the corticosteroid medicine right into your lungs, minimising the amount of contact that it has with your mouth.
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