Candidiasis, Oral (adults)

Symptoms

Oral thrush is a fungal infection of the mouth. It is not contagious and is usually successfully treated with antifungal medication.

It is also called oral candidosis (or candiasis) because it is caused by a group of yeasts called Candida.

Symptoms of oral thrush can include:

white patches (plaques) in the mouth that can often be wiped off, leaving behind red areas that may bleed slightly
loss of taste or an unpleasant taste in the mouth
redness inside the mouth and throat
cracks at the corners of the mouth
a painful, burning sensation in the mouth

In some cases, the symptoms of oral thrush can make eating and drinking difficult.

When to seek medical advice

Speak to your GP if you develop symptoms of oral thrush. If left untreated, the symptoms will often persist and your mouth will continue to feel uncomfortable.

In severe cases that are left untreated, there is also a risk of the infection spreading further into your body, which can be serious.

Your GP will usually be able to diagnose oral thrush simply by examining your mouth. Sometimes they may also recommend blood tests to look for certain conditions associated with oral thrush, such as diabetes and nutritional deficiencies.

In most cases, your GP will be able to diagnose oral thrush simply by examining your mouth. However, some tests may also be used to confirm the diagnosis.

Your GP may recommend you have a blood test to look for certain conditions associated with oral thrush, such as diabetes and nutritional deficiencies.

A biopsy may also be used. This involves taking a sample of the white patches in your mouth to check for the candida fungus under a microscope.

Your GP may also take a swab from the affected area to monitor how the fungus grows over a period of several days.

What causes oral thrush?

Low numbers of the fungus Candida are naturally found in the mouth and digestive system of most people. They don't usually cause any problems, but can lead to oral thrush if they multiply.

There are a number of reasons why this may happen, including:

taking a course of antibiotics, particularly over a long period or at a high dose
taking inhaled corticosteroid medication for asthma
wearing dentures (false teeth), particularly if they don't fit properly
having poor oral hygiene
having a dry mouth, either because of a medical condition or a medication you are taking
smoking
having chemotherapy or radiotherapy to treat cancer

Babies, young children and elderly people are at a particularly high risk of developing oral thrush, as are people with certain underlying conditions, including diabetes, an iron deficiency or vitamin B12 deficiency, an underactive thyroid (hypothyroidism) and HIV.

As most people already have Candida fungi living in their mouth, oral thrush is not contagious. This means it cannot be passed to others.

Oral thrush infections are caused by increased levels of Candida albicans fungi, which are naturally present in the mouth.

This increase may result from:

using an inhaler to take corticosteroid medication
certain medications which reduce the amount of saliva produced
an injury in the mouth
smoking
the immune system being weakened (immunodeficiency)
an underlying health condition, such as cancer or HIV

Corticosteroids can be used to reduce inflammation (swelling) and treat a variety of conditions such as:

some types of cancer
arthritis, a condition that causes inflammation of the bones and joints
eczema, a long-term skin condition that causes itchy, dry and red cracked skin
asthma, a long-term condition that causes the airways of the lungs to become inflamed and swollen
COPD, (chronic obstructive pulmonary disease) a collective name for lung diseases (including chronic bronchitis, emphysema and chronic obstructive airways disease) that cause breathing difficulties

Inhaled corticosteroids are often used to treat asthma. The medicine is delivered through an inhaler, or spacer, (a plastic cylinder attached to your inhaler which increases the amount of medication reaching the lungs and minimising contact with your mouth). Inhaled corticosteroids cause fewer side effects than other forms of treatment but can change acidity levels in the mouth. The change kills healthy bacteria and causes 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

Treating oral thrush

Oral thrush can usually be successfully treated with antifungal medicines. These usually come in the form of gels or liquid that you apply directly inside your mouth (topical medication), although tablets or capsules are sometimes used.

Topical medication will usually need to be used several times a day for around 7 to 14 days. Tablet or capsules are usually taken once daily.

These medications don't often have side effects, although some can cause nausea (feeling sick), vomiting, bloating, abdominal (tummy) pain and diarrhoea.

If antibiotics or corticosteroids are thought to be causing your oral thrush, the medicine – or the way it is delivered – may need to be changed or the dosage reduced.

Oral thrush can be successfully treated with a course of antifungal medicines prescribed by your GP taken over seven to 14 days.

Antifungal treatments are available in the following forms:

gels
tablets
lozenges
powders
creams
rinses

Rinses are useful for people with a dry mouth who are unable to swallow antifungal tablets.

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.

Antifungal medicines used to treat oral thrush include:

miconazole
nystatin
fluconazole
clotrimazole
econazole

If antibiotics or corticosteroids are thought to be causing your oral thrush, the medicine, or the way it is delivered, may need to be changed or the dosage reduced.

Good dental hygiene and not smoking are also recommended.

Some antifungal medications should not be used if you are pregnant, breastfeeding or taking other medications. Your GP or pharmacist will advise you if you have any questions on how to take these treatments.

Side effects

Possible side effects of antifungal medicines include:

nausea (feeling sick)
tummy pain
diarrhoea
headache
indigestion

Preventing oral thrush

There are a number of things you can do to reduce your chances of developing oral thrush, including:

rinsing your mouth after meals
brushing your teeth twice a day with a toothpaste that contains fluoride and interdental cleaning (flossing) regularly
visiting your dentist regularly for check-ups, even if you wear dentures or have no natural teeth
removing your dentures every night, cleaning them with paste or soap and water before soaking them in a solution of water and denture-cleaning tablets
brushing your gums, tongue and inside your mouth with a soft brush twice a day if you wear dentures or have no or few natural teeth
visiting your dentist if your dentures do not fit properly
stopping smoking if you smoke
rinsing your mouth with water and spitting it out after using a corticosteroid inhaler, and using a spacer (a plastic cylinder that attaches to the inhaler) when you take your medicine
ensuring that any underlying condition you have, such as diabetes, is well controlled

If you have a condition or are receiving treatment that could put you at a high risk of developing oral thrush, your doctor may recommend taking a course of antifungal medication to prevent this happening.

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.

They should be removed and cleaned every night by brushing with warm, soapy water and scrubbing the non-polished side of the dentures with a nailbrush.

Dentures can then be soaked in any liquid used to sterilise 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 yeast growth in your mouth and increases your chance of getting oral thrush.

Speak to your GP if you want to give up smoking. Several treatments are available to increase your chance of quitting successfully, and your GP can put you in touch with local support groups and one-to-one counsellors.

The NHS Smoking Helpline also offers advice and encouragement to help you give up smoking. You can phone the helpline (0800 022 4 332) or visit the NHS Go Smokefree website.

The 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 plastic cylinder which attaches to your inhaler and can help to get the corticosteroid medicine right into your lungs, minimising contact with your mouth.