Oral thrush

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at December 24, 2016
StartDiseasesOral thrush

The Candida albicans fungus is a microorganism that naturally lives within different parts of the human body. However, when this fungus starts growing excessively, it can cause medical problems such as oral thrush. This condition is generally very treatable.


Definition & Facts

Oral thrush occurs when excessive amounts of the Candida albicans fungus starts to accumulate in the mouth. It can grow on the tongue, inner cheeks, gums, or roof of mouth. Oral thrush is most common among infants, seniors, and people with a weakened immune system. However, it can happen to anyone under certain circumstances. Oral thrush causes symptoms that are often uncomfortable.

Symptoms & Complaints

The primary symptom of oral thrush is the appearance of white lesions on the inner surfaces of the mouth. The lesions tend to look somewhat like cottage cheese and have a slightly raised appearance.

The area around the white patches can be cracked or reddened. If the lesions are disturbed, bleeding may occur. Patients tend to have mouths that feel sore and rough. When the oral thrush is on the tongue, it causes a cottony feeling and prevents people from tasting food correctly. In some cases, oral thrush may affect the outer edges of the lips or mouth, causing cracked, dry, reddened skin.

The oral thrush can be severe enough to make eating and swallowing difficult. If the oral thrush is particularly severe, it can travel down the esophagus. When this occurs, patients feel like something is stuck in their throat and have difficulty swallowing. Young children with oral thrush may not be able to express themselves, so it can be slightly more difficult to notice symptoms in an infant. Infants with thrush tend to cry more often and have trouble eating.


In a healthy person, there are always trace amounts of Candida albicans fungi, but the immune system helps prevent the fungi from growing in excessive amounts. However, if the immune system is not fully functioning, the fungi may grow unchecked. This is why infants often develop oral thrush. Anything that hampers the immune system can cause issues. People who have HIV/AIDS, cancer, or other disorders which affect the immune system are likely to get oral thrush.

The growth of Candida is normally checked by other beneficial probiotic organisms in the body. If these probiotic organisms are killed by antibiotics, prednisone, or other medications, then the Candida albicans may be left to flourish unchecked.

Oral thrush may also be caused by an excessive amount of sugar and carbohydrates in the diet. The growth of the fungi may be encouraged by trace amount of sugar in the saliva. Patients with diabetes mellitus tend to have higher amounts of sugar in their saliva and are more likely to get oral thrush.

In some instances, oral thrush may be linked to a vaginal yeast infection because a yeast infection is caused by the same fungi. A mother with a yeast infection may pass oral thrush on to her child during birth, or a person can get oral thrush by performing oral sex on a partner with a yeast infection.

Diagnosis & Tests

In most instances, oral thrush is diagnosed with a simple physical examination. The white lesions are generally noticeable and unique enough that a doctor can diagnose a patient with oral thrush based just on their appearance. However, if there is some uncertainty about the symptoms, a patient will be diagnosed with a culture test. In this test, an affected portion of the mouth is swabbed with a piece of cotton. The sample is then cultivated in a lab to examine the bacteria or fungi that were growing on the sample. If large amounts of the Candida albicans fungi are present, than a patient is diagnosed with oral thrush.

In the rare cases where oral thrush is primarily located in the esophagus, more invasive tests are required. Generally, a patient will need an endoscopic exam if they are complaining of something in their throat. The doctor will guide a small, flexible tube with a light and tiny camera through the mouth and down the esophagus. This allows the doctor to look at the inside of the throat and see the characteristic lesions of oral thrush.

Treatment & Therapy

Most patients who have oral thrush will be cured after a simple course of antifungal medications. These medications can be administered as a tablet, liquid, or lozenge, and patients normally need to take them for 10 to 14 days to see a noticeable effect. It is important to keep taking the medication for the entire recommended time so that a recurrence does not occur.

There is some evidence that eating yogurt while taking medications can be more effective because the probiotics in yogurt help to slow down the growth of the Candida albicans fungus. If a patient has a significantly weakened immune system, basic antifungal medications may not work. In these cases, doctors typically prescribe a course of amphotericin B, but this can have some rather unpleasant side effects.

If a breastfeeding infant has oral thrush, the thrush can infect the mother's breasts. To avoid reinfecting the infant, the mother may need to use an antifungal cream on her chest along with an oral antifungal medication for the infant. 

Prevention & Prophylaxis

To avoid another bout of oral thrush, anything that was in contact with the patient's mouth, such as toothbrushes, thermos lids, pacifiers, or bottle nipples should be sterilized or replaced. Limiting sugar intake and consumption of yeasty foods like bread and beer can help to prevent oral thrush from happening in the first place.

It is also important to brush teeth regularly and clean any dentures daily. Avoiding intimate contact with anyone that has a vaginal yeast infection is an important preventative measure. One may also be able to reduce oral thrush risks by regularly eating probiotic foods like yogurt, sauerkraut, or kombucha.