What is Oral thrush?

Oral thrush

What is oral thrush?

Oral thrush is an infection that can affect almost any part of your mouth and throat.

Thrush is caused by a type of

fungus
A fungus is an organism that is sometimes considered to be a type of plant. A fungus lives by feeding on other organisms. The mushrooms we eat in salads are fungi, but so are candida and cryptococcus, which can cause infections in people's bodies.

fungus called Candida.

You can get oral thrush in your mouth or in your throat.

It's normal to have small numbers of Candida in your body, including on your skin and in your mouth. These are usually harmless and don't cause any symptoms.

But sometimes thrush grows out of control and you get an

infection
You get an infection when viruses, bacteria, fungi or other tiny organisms get into your body. These bugs are so tiny that you can't see them without a microscope. For example, an infection in your airways causes the common cold. And an infection in your skin can cause rashes such as athlete's foot.

infection in your mouth. You can get thrush on your tongue, your gums, on the inside of your cheeks, on the roof of your mouth or in your throat.

Source:
Elllepola ANB, Samaranayakel LP.
Oral candidal infections and antimycotics.
Critical Reviews in Oral Biology and Medicine. 2000; 11: 172-198.

You can get Candida infections in many other parts of the body, such as your skin or your groin. Babies can get Candida infections in their diaper area. And women can get Candida infections in their vagina. To find out more, see Yeast infection, vagina.

Who gets oral thrush?

Some people are more likely than others to get oral thrush. This is usually because they have another disease or are taking a drug treatment that makes their

immune system
The immune system is made up of the parts of the body that are devoted to fighting infection. The body is constantly being threatened by infections from things like bacteria, viruses and parasites. The immune system fights these infections in different ways. At the microscopic level, the immune system uses antibodies and white blood cells, which travel in the blood and target infectious agents, such as bacteria. These microscopic parts of the immune system either kill the infectious agent directly, or take it to other parts of the body, like the spleen, where it can be dealt with. The lymph nodes are another important part of the immune system. Within them, white blood cells filter through the foreign material that has entered the blood, to see if there are any infections. When you have a swollen gland during a cold, this is actually a lymph node that is reacting to the infection. Unfortunately, it is possible for the immune system to become confused and to use its destructive powers to target healthy parts of the body. Diseases that result from this type of situation are called autoimmune diseases.

immune system weak.

Source:
Elllepola ANB, Samaranayakel LP.
Oral candidal infections and antimycotics.
Critical Reviews in Oral Biology and Medicine. 2000; 11: 172-198.

¹ Your immune system helps your body fight off infections. When it isn't working properly, fungi that normally live in your body without causing any problems can grow out of control and cause infections.

People who are more likely to get oral thrush include those with:

Source:
Elllepola ANB, Samaranayakel LP.
Oral candidal infections and antimycotics.
Critical Reviews in Oral Biology and Medicine. 2000; 11: 172-198.

A weak immune system from taking certain medications or other treatments. For example, anti-cancer (chemotherapy) drugs and steroids can affect the immune system, and so can

radiation therapy
This treatment uses high-energy X-rays to kill cancer cells. It's most often used for tumors that are hard to treat with surgery alone. You won't feel any pain during this treatment, but you may get some side effects afterward.

radiation therapy
Diseases that weaken their immune system. These include

AIDS
AIDS stands for acquired immunodeficiency syndrome. People who are infected with the human immunodeficiency virus (HIV) get AIDS when the virus has destroyed most of their immune system. When people have AIDS, their body isn't able to fight infections. So even common infections, such as colds, can cause serious problems.

AIDS and

leukemia
Leukemia is a type of cancer that affects the body's production of white blood cells. White blood cells are important for fighting infections. So, if you have leukemia you are more likely to catch an infectious disease.

leukemia
diabetes
Diabetes is a condition that causes too much sugar to circulate in your blood. It happens when your body stops making a hormone called insulin (type 1 diabetes) or when insulin stops working (type 2 diabetes).

Diabetes. If you have diabetes, you have too much sugar in your blood. Thrush grows best in sweet conditions, which can happen if sugar levels in your blood and saliva are high
A severe, long-term dry mouth. Thrush finds it easier to grow in a mouth where there isn't much saliva. You can get a dry mouth when you take certain drug treatments, and after radiation therapy or surgery on your neck or head.

Babies are also more likely to get oral thrush because the part of their bodies that keeps fungi and other germs under control (the immune system) is not properly developed.

Source:
Hope JE.
Treatment of oropharyngeal candidiasis and candidal diaper dermatitis in neonates and infants: review and reappraisal.
Pediatric Infectious Disease Journal. 1997; 19: 885-894.

Oral thrush is also more common in people who:

Source:
Elllepola ANB, Samaranayakel LP.
Oral candidal infections and antimycotics.
Critical Reviews in Oral Biology and Medicine. 2000; 11: 172-198.

Smoke. We don't fully understand why smokers are more likely to get oral thrush, but they tend to have more thrush fungi in their mouth. The smoke also alters the defenses in your mouth that normally stop thrush from growing out of control
Wear badly fitting dentures or have poor oral hygiene
Have recently taken

antibiotics
These medications are used to help your immune system fight infection. There are a number of different types of antibiotics that work in different ways to get rid of bacteria, parasites and other infectious agents. Antibiotics do not work against viruses.

antibiotics to treat another infection. Antibiotics can kill friendly as well as harmful

bacteria
Bacteria are tiny organisms. There are lots of different types. Some are harmful and can cause disease. But some bacteria live in your body without causing any harm.

bacteria, and this can allow thrush to grow
Have a high-carbohydrate diet
Have low blood levels of iron or vitamins such as B12 and folate.

Sources for the information on this page:

Elllepola ANB, Samaranayakel LP.Oral candidal infections and antimycotics.Critical Reviews in Oral Biology and Medicine. 2000; 11: 172-198.

Hope JE.Treatment of oropharyngeal candidiasis and candidal diaper dermatitis in neonates and infants: review and reappraisal.Pediatric Infectious Disease Journal. 1997; 19: 885-894.

This information was last updated on May 08, 2009

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment.
© BMJ Publishing Group Limited 2009. All rights reserved.

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