Antifungal Resistance

Antifungal resistance occurs when antifungal medicines can’t stop the growth of a fungal infection. People with weak immune systems are most at risk. Superbugs like Candida auris don’t respond to antifungals, which limits treatment options. You can lower the risk of antifungal resistance by taking medicine as prescribed.

What is antifungal resistance?

Antifungal resistance occurs when an antifungal medication no longer works to treat a fungal infection. The fungus can fight off the medicine’s effects.

This problem is a type of antimicrobial resistance. It occurs when fungi, viruses, bacteria and parasites don’t respond to medications developed to treat them. Your body doesn’t develop antifungal resistance — fungi do. Today, while antifungal medicines may still help you, fewer drugs can treat drug-resistant fungi.

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What are antifungal medications?

Antifungal drugs help your body get rid of certain fungal infections. They treat fungal skin infections like yeast infections, athlete’s foot, jock itch and ringworm. Antifungal medicines also manage infections that affect the lungs, brain and blood.

Why is antifungal resistance a problem?

Drug resistance is a serious global health problem. It greatly limits treatment options. If a fungus doesn’t respond to one of three available classes of antifungal drugs, the other options may be less effective. Some drugs cause more severe, potentially toxic side effects.

Nearly 3 million Americans will develop a drug-resistant infection this year. More than 35,000 of them will die.

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What causes antifungal resistance?

There are several causes of antifungal resistance:

  • Improper use of antifungal medicines: When you skip doses, stop treatment too soon or receive a dose that’s too low, a fungus gets better at fighting off the medicine’s effects.
  • Antibiotic use: Antibiotics kill harmful bacteria. But they can also kill helpful bacteria in the digestive tract. As a result, Candida, a yeast naturally found inside the digestive tract, can start to grow too fast. A person taking antibiotics may then need antifungals to treat a yeast infection called candidiasis. Frequent treatment raises the risk of drug resistance to both treatments.
  • Fungicide use: People who work closely with crops treated by fungicides may be more prone to fungal infections that are antifungal-resistant. In these environments, fungi have increased exposure to fungicides. Fungicides are a type of antifungal that keeps crops from getting moldy.
  • Natural resistance: Certain fungi never respond to antifungals. They’re naturally resistant to medicines.
  • Spontaneous resistance: A fungus stops responding to a once-effective medicine for no known reason.
  • Transmitted resistance: You can spread a contagious drug-resistant fungal infection to someone else. That person now has an infection that won’t respond to an antifungal, even if they’ve never used the medicine.

Who is at risk for developing antifungal resistance?

People who have weakened immune systems are more likely to develop serious fungal infections that can lead to antifungal resistance. This includes people who have:

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What are the complications of antifungal resistance?

Certain strains of fungi have become more resistant to antifungal medicines. They’re known as superbugs. These fungi continue to multiply and cause infections even when you take medication.

There are only three classes of antifungal medicines: azoles, echinocandin and polyenes. A fungus that develops resistance to one drug may not respond to any available treatments.

What are antifungal superbugs?

Fungal infections with superbug status include:

  • Aspergillus fumigatus: This mold causes a lung infection called aspergillosis. Approximately 200,000 people worldwide develop aspergillosis every year. They typically get it from breathing in the mold spores. The infection is becoming more resistant to azole antifungals.
  • Candida: This yeast naturally occurs on the skin and inside the body. Candida can enter the bloodstream, causing a potentially life-threatening infection called candidemia. This infection no longer responds well to azole medicines.
  • Candida glabrata: C. glabrata affects the urinary system. It’s becoming more resistant to azoles and echinocandins. That leaves people with few safe treatment options.

What is Candida auris?

Candida auris (C. auris) is a relatively new fungal superbug that first appeared in 2009. It quickly caused problems worldwide and is becoming more common in the United States. Antifungals that typically work on Candida infections don’t always work against this strain. Some strains are multi-drug resistant. These C. auris infections don’t respond to any antifungal drugs.

The fungus causes bloodstream infections that can affect the heart and brain. When this happens, more than 1 in 3 infected people die. The fungus spreads easily in hospitals and nursing homes. People get it through contact with an infected person or contaminated surfaces. It can live on surfaces for several weeks and is difficult to get rid of.

How are antifungal-resistant infections treated?

If one class of antifungal drugs doesn’t help, your healthcare provider may try a medicine from a different class. There’s a limited number of effective antifungal treatments. If an infection doesn’t respond to antifungals, your provider may try different medicines. Unfortunately, these drugs may have more severe side effects.

Can you prevent antifungal resistance?

Taking antifungal medicine as prescribed is the best way to prevent antifungal resistance. You can set reminders on your phone so you don’t forget to take it. Contact your healthcare provider if you miss a dose to find out what to do. Often, it’s best to take the next dose as soon as you can.

A note from Cleveland Clinic

Antifungal resistance can occur for many reasons. It sometimes develops spontaneously. Or it may result from antibiotic overuse or misuse of antifungal medicines. People with compromised immune systems are most at risk for developing fungal infections that can lead to antifungal resistance. Some fungi, known as superbugs, don’t respond to standard antifungal treatments. It’s important to take antifungal medicines as prescribed to lower the risk of drug resistance.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 05/28/2021.

Learn more about our editorial process.

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