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An antifungal agent is a substance that kills fungi or inhibits its growth. There are many types of antifungals used to treat a range of illnesses and conditions caused by fungi. Some of these agents are topical while others are meant to be ingested. Many antifungal agents can be purchased over the counter for use without a doctor's guidance, but some are available only by prescription.
One type of antifungal agent is called a systemic antifungal. This type is usually taken orally, though doctors sometime administer them intravenously, which means through a vein. Some commonly prescribed antifungals are fluconazole, ketoconazole, and terbinafine.
Topical agents are meant to be applied to the skin or nails, but some can be placed into the body’s cavities. There are three primary categories of topical antifungal agents: azoles, allylamines and benzylamines, and polyenes. Each category works to destroy fungi in a slightly different way.
Polyenes kill fungi cells. They do this by binding to their cell membranes and making them leak. This type of topical antifungal was one of the first to be developed. Commonly used types of polyenes include nystatin and amphotericin B.
Azoles are another type of topical antifungal agent. They work to block a critical substance called ergosterol in fungi cell walls. This weakens the cell wall, causing the cells to eventually die. Clotrimazole, ketoconazole, miconazole, and oxiconazole are among the commonly prescribed azoles.
Allylamines and benzylamines are another class of topical antifungals. These topical agents act in a similar manner to azoles, interfering with ergosterol. They interfere with this substance earlier on in its production process, however. As such, they are helpful for both inhibiting growth and killing fungi. Among the commonly used types of antifungals in this class are butenafine, naftifine, and terbinafine.
As with other types of medications, antifungal agents may cause side effects, regardless of whether they are used in over-the-counter or prescription form. Among the side effects possible with topical agents are burning, itching, minor pain, and rash where the antifungal agent is applied. Systemic agents are typically only available by prescription and may cause stomach upset, hives, rashes, itching, sight and taste disturbances, and headaches.
Most people who use antifungal medications do not experience side effects. Systemic antifungal medication can cause severe side effects in some people, however. For example, some of these drugs can damage the liver and the kidneys. They may even damage the heart and diminish a person’s white blood cell count, possibly making it harder for him to fight off infections. For these reasons, doctors often monitor their patients’ health while these medications are in use.