Oral thrush in adults

Oral thrush is a fungal infection of the mouth. You can't pass it on to other people, and it usually clears up well with antifungal medicine.

Doctors also call it oral candidosis (or candiasis), because a group of yeasts called Candida causes it.

See a doctor if you develop symptoms of oral thrush. These 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, oral thrush can make eating and drinking difficult.

If you leave it untreated, the symptoms will often persist and your mouth will continue to feel uncomfortable. In severe cases that go untreated, there is also a risk of the infection spreading further into your body, which can be serious.

A doctor can usually diagnose oral thrush simply by examining your mouth. Sometimes they may also recommend blood tests to look for certain conditions associated with it, such as diabetes and nutritional deficiencies.

Most people have a small amount of the fungus Candida living in the mouth and digestive system. It doesn't usually cause any trouble, but if it multiplies it can lead to oral thrush.

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 medicine 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 medicine 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. So are people with certain underlying conditions, including diabetes, an iron deficiency or vitamin B12 deficiency, an underactive thyroid (hypothyroidism) and HIV.

Because 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 can usually be treated well with antifungal medicines. Most often these are gels or liquids that you put directly inside your mouth (called topical medication), though tablets or capsules are sometimes used instead.

Topical medication usually has to be used several times a day for around 7 to 14 days. Tablets or capsules are normally taken once a day.

These medicines don't often cause side effects. 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 may need to be reduced.

There are several things you can do to lower your chances of getting oral thrush.

• rinse your mouth after meals
• brush your teeth twice a day with a toothpaste that contains fluoride
• floss regularly
• visit your dentist regularly for check-ups, even if you wear dentures or have no natural teeth
• take your dentures out every night and clean them with paste or soap and water, then soak them in a solution of water and denture-cleaning tablets
• if you wear dentures or have no or few natural teeth, brush your gums, tongue and the inside of your mouth with a soft brush twice a day
• visit your dentist if your dentures don't fit properly
• stop smoking if you smoke
• after using a corticosteroid inhaler, rinse your mouth with water and spit it out, and use a spacer (a plastic cylinder that attaches to the inhaler) when you take your medicine
• make sure any underlying condition you have, such as diabetes, is well controlled

If you have a condition, or are having treatment, that puts you at high risk of oral thrush, your doctor may recommend a course of antifungal medicine to stop it happening.