The prevention and treatment of oral thrush

Photo of a dentist and patient (AdamGregor / iStockphoto / Thinkstock)

If someone is at higher risk of developing oral thrush, it is a good idea to try to take preventive measures. Aside from various forms of oral hygiene, antimycotics (antifungal drugs) can be used to prevent oral thrush. These medications can also be used to treat this infection.

Oral thrush, also known as candidiasis, is a fungal infection in the mouth and throat area. It is caused by types of yeast fungus called Candida that grow on the mucous membranes lining the mouth and throat. Many people have a small amount of this kind of fungus on their mucous membranes without having any noticeable problems. But given the right conditions, the yeast fungus can start reproducing very quickly. The infection appears as a white coating and red inflamed areas in the mouth and throat region. It is sometimes painful and can impair your sense of taste, as well as making it difficult to speak or eat.

The risk of oral thrush is higher in people who have a weakened immune system, for instance due to a chronic disease or an intensive treatment such as chemotherapy. It is also common in people who have HIV/AIDS, and is often quite distressing. Some end up eating very little because of the pain in their mouth and throat, which can make their body even weaker.

How can you improve oral hygiene?

There are a number of different recommendations for preventing oral thrush in people who are at a greater risk of getting it. But these have not yet been tested enough in scientific studies. This means that it is not clear whether, for instance, a particular form of oral hygiene can in fact prevent oral thrush. But it is generally important to take care of your teeth and gums, as well as the lining of your mouth, and to avoid injury to that area.

Chemotherapy and radiotherapy of the head and neck region can damage tissue in the mouth, increasing the risk of oral thrush. Dental plaque and food leftover in your mouth make it easier for the yeast to grow or inflammations to develop. These are all reasons to practice thorough oral hygiene during cancer treatment, but also to be especially careful, for example by using a softer brush. When cleaning the spaces between your teeth (e.g. with dental floss) it is important to take care to avoid injuring the mucous membrane lining. Many people also rinse their mouth with special antiseptic mouthwashes during chemotherapy or radiotherapy.

It can be a good idea to visit the dentist before having cancer treatment in the head and neck region so that health problems such as gingivitis can be detected and treated. Your dentist can also help with oral hygiene and oral thrush prevention during and after cancer treatment.

If you wear dentures (false teeth), different factors may increase the likelihood of oral thrush. These include things like a poor fit, rough surfaces, leftover food and especially dental plaque. For this reason, dentures should be cleaned regularly, for example with a toothbrush and a special cleaning solution.

If people need nursing care and eat or drink very little, it is important to keep their mouth moist enough and to regularly offer them something to drink. Cleaning the mouth several times a day and removing plaque can help prevent inflammations from developing and yeast infections from arising.

How can oral thrush be prevented during cancer treatment?

During cancer treatment it may help to take antifungal drugs as a precaution. Antifungal drugs – also called antimycotics – are used to treat fungal infections. They slow fungal growth or destroy any fungi present, so they should stop fungal infections from developing and also stop them from spreading to the rest of the body. How antimycotic drugs are absorbed by the body will depend on the dosage form and mechanism of action. There are

  • drugs that have an effect on a limited, local region (topical drugs) and
  • drugs that have an effect on the entire body (systemic drugs), as well as
  • drugs that do both.

Antimycotics are available in different forms: for example as mouthwashes, ointments, lozenges, syrups, tablets or infusions. Studies have shown that some drugs that affect the entire body can lower the risk of developing fungal infections. These types of drugs can be taken as capsules, for instance, or given as an infusion. Drugs that are intended to have both topical and systemic effects can be taken in the form of lozenges, for example. There is no evidence that antimycotic drugs that affect only the mouth (topical antimycotics) are effective. These types of drugs are often available in the form of ointments and mouthwashes.

Research summaries

How can oral thrush be prevented in people with HIV/AIDS?

Oral thrush is a problem that keeps on cropping up for many people who have HIV/AIDS. For this reason, prevention is especially important for them. Fluconazole is the only antimycotic drug that has been proven to effectively prevent oral thrush in people who have HIV/AIDS. Taking fluconazole tablets can lower the risk of oral thrush. In older studies, about half of the people with HIV/AIDS developed oral thrush without taking any preventative measures. Taking fluconazole regularly reduced the rate to about one third.

But regular preventive use has its disadvantages too. For instance, fluconazole can cause headaches, stomach ache and nausea. Taking this medication for months at a time can also cause fungi to become resistant to it. This may make the medication less effective if it is later needed to treat an infection. For this reason, the preventive use of fluconazole is only recommended for infections that keep coming back.

What are the treatment options for oral thrush?

If someone develops oral thrush during cancer treatment, it can be treated with antimycotic drugs. Both topical and systemic medications can be considered. Medications that you swallow or drink are probably more effective than topically applied medications. Due to a lack of research, it's not possible to say whether certain drugs are more effective than others during cancer treatment.

People who have HIV/AIDS can also use various antimycotics to treat oral thrush, including fluconazole, ketoconazole, itraconazole and clotrimazole. Fluconazole and ketoconazole, which are absorbed by the digestive tract, were shown to be more effective than nystatin, which is used topically.

The most common side effects of systemic antimycotic drugs are temporary problems like headaches, skin rashes, nausea, bloating and diarrhea. The most suitable medication will depend on your general health and the severity of the infection. The medications are usually taken over a time period of about one to two weeks.