Candida Infection: Thrush

What is thrush?

Thrush is a fungal infection. It occurs in your mouth and throat.

Your mouth and throat normally contain millions of tiny organisms. These include bacteria and yeast. Most of these organisms do not cause any problems. In fact, they may help fight disease.

Yeasts are a type of fungus. A type of yeast called Candida normally lives on the mucous membranes of your mouth and throat. Usually, this yeast grows only in small numbers and is harmless. But under certain circumstances the Candida fungus can grow out of control and cause thrush.

Thrush does not usually affect healthy adults. It is more common in people with impaired immune systems. It is also more likely in people who take certain kinds of medicines. Thrush is normally not contagious.

There are 2 major kinds of thrush:

  • Pseudomembranous form. This is the more common form. It appears as white patches on your mouth, tongue, or back of your throat. The less common
  • Atrophic form. This is the less common form. It is usually found in older adults. It typically appears as red patches underneath upper dentures.

Thrush is sometimes linked to other kinds of Candida infections. For example, people who have thrush sometimes have a Candida infection of the esophagus as well. The term thrush refers to a local infection of only the mouth and throat. But Candida sometimes causes infection in other areas of the body.

What causes thrush?

Thrush happens when the Candida fungus multiplies inside your mouth and throat. It crowds out other organisms. Circumstances that throw off the normal balance of organisms can trigger thrush. One example is when you take antibiotics. These medicines may kill some of the normal bacteria present in your mouth. Candida is unaffected by the antibiotics. So the fungus can then multiply freely. That is why people on antibiotics have an increased risk of thrush.

Other factors that can disrupt the normal balance of organisms and increase the risk of thrush are:

  • Dentures
  • Chemotherapy
  • Radiation therapy
  • Diabetes
  • Organ transplantation
  • Corticosteroid use
  • Immune deficiency, such as from AIDS

Several types of Candida can cause an infection. But the most common one is Candida albicans.

Who is at risk for thrush?

You may have an increased risk for thrush if you have any of the above factors that disrupt the balance of organisms. Older adults and infants also have an increased risk for it.

What are the symptoms of thrush?

If you have thrush, you might have the following symptoms:

  • Cottony feeling in your mouth
  • Loss of taste
  • Pain while eating or swallowing
  • White or red patches inside your mouth or on the back of your throat
  • Cracking at the corners of your mouth

Some people with thrush don’t have any symptoms.

How is thrush diagnosed ?

Your healthcare provider will take your medical history. He or she will ask you about your symptoms and your past health information. Your healthcare provider will also look closely at your mouth and throat. If there are any white or red patches, your provider will scrape the affected area with a tongue depressor. A simple lab test of the sample can usually confirm thrush.

If you don’t have a known health problem that puts you at risk for thrush, you may need follow-up testing. For example, you may need an HIV test to figure out if you have a condition you don't yet know about.

Esophageal candidiasis often exists along with thrush (especially in people who have HIV). If you do have thrush, your healthcare provider may also check for this condition. You might need an upper endoscopy. It’s a procedure that allows your healthcare provider to look at your esophagus and also take a tissue sample for testing.

How is thrush treated?

Your healthcare provider will figure out the best treatment for you based on:

  • Your age, overall health, and medical history
  • How sick you are
  • How well you can handle certain medicines, treatments, or therapies
  • How long the condition is expected to last
  • Your opinion or preference

It is important to treat thrush early to relieve the pain and trouble swallowing, and to prevent spread of infection. 

Thrush is usually treated with antifungal medicine. These medicines are placed directly on your mouth and throat. They may include a swish and swallow medicine or an antifungal lozenge. They target the Candida overgrowth.

If the thrush doesn’t respond to this treatment, you may need an antifungal pill. This medicine removes Candida throughout the body. The length and type of your therapy will depend on several factors. These include the severity of your infection and any other health problems. In rare cases, you may need to take medicine through an IV.

Some people may also need ongoing preventive treatment with oral antifungal medicines. You might need them if you are at continued high risk for thrush.

Typically, your healthcare provider can manage the diagnosis and treatment of thrush. But you may need to see an infectious disease specialist.

What are the complications of thrush?

Systemic infection from thrush is very unlikely.  However, people who are debilitated and develop thrush usually have serious problems with their immune system. These people are at high risk of developing a much more serious Candida infection throughout their body. Additional risk factors for systemic infection in very ill people include:

  • Central venous lines
  • IV nutrition
  • Broad-spectrum antibiotics
  • Kidney failure
  • Recent surgery

What can I do to prevent thrush?

You may be able to help prevent some cases of thrush. That is especially important if you have a health problem that increases your risk for it.

  • Practice good oral hygiene. Try using a chlorhexidine mouthwash.
  • Clean your dentures regularly as instructed. Make sure they fit you correctly.
  • After using a corticosteroid inhaler, rinse out your mouth with water or mouthwash.
  • Avoid broad-spectrum antibiotics. Use them only if you really need them.
  • Get proper treatment for health problems that increase your risk of thrush, like diabetes.

When should I call my healthcare provider?

If you have a health problem that raises your risk of thrush, call your healthcare provider at the first sign of symptoms.

Key points

  • Thrush is a fungal infection of your mouth and throat. It is caused by an overgrowth of Candida yeast.
  • Antibiotics and immune system problems can raise your risk of thrush. It is uncommon in people without underlying conditions.
  • Thrush might cause a cottony feeling in your mouth, or a loss of taste.
  • Usually, antifungal medicine can treat thrush.
  • Sometimes untreated thrush may turn into a more serious infection, especially in people who are very ill. Prompt treatment for thrush can help prevent that.
  • Practicing good oral hygiene can prevent some cases of thrush.
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