Antifungals

Key takeaways

• Antifungals treat infections from fungi and yeasts: athlete's foot, ringworm, nail infections and thrush. Topical creams treat the skin surface; oral tablets reach infections deeper in the body.
• Clotrimazole and miconazole are common topical treatments; fluconazole and itraconazole are oral options for internal or stubborn infections.
• Prolonged oral courses of itraconazole, terbinafine or ketoconazole need periodic liver-function blood tests, since all three can affect the liver over weeks of continuous use.
• Betamethasone is not an antifungal. It is a corticosteroid, sometimes combined with an antifungal such as clotrimazole to calm inflammation while the antifungal clears the infection.

How antifungals work

Antifungal drugs stop fungal cells from building or maintaining their outer membrane, halting their growth or killing them outright. Topical creams act only where applied; oral tablets travel through the bloodstream to reach infections in nails, hair follicles or internal tissue a cream cannot penetrate.

Choosing between clotrimazole, terbinafine, fluconazole, itraconazole, ketoconazole, voriconazole and betamethasone combinations

• Clotrimazole: a topical treatment for athlete's foot, ringworm and vaginal thrush, applied to the affected area for one to two weeks. It does not enter the bloodstream in meaningful amounts.
• Terbinafine: a cream for skin infections or a tablet for nail infections. Oral courses for toenail fungus often run for weeks to months, and prolonged oral use calls for a baseline and follow-up liver-function test.
• Fluconazole: an oral tablet, often given as a single dose for vaginal thrush or a longer course for other yeast infections. It interacts with several other medicines through the liver, so tell your prescriber about everything else you take.
• Itraconazole: an oral medicine for systemic or resistant fungal infections and some nail infections. Extended courses need liver-function monitoring, and it should not be combined with certain heart medicines.
• Ketoconazole: found in medicated shampoos for fungal scalp conditions and, less often, as an oral tablet. Oral ketoconazole carries a stronger liver-injury risk than the other azoles, reserved for infections that resist other options, with liver tests before and during treatment.
• Voriconazole: an oral or intravenous medicine for serious, deep-seated fungal infections, typically started in hospital and monitored closely, including liver function and vision changes.
• Betamethasone combinations: betamethasone itself is a corticosteroid, not an antifungal. Paired with clotrimazole in one cream, it reduces itching and redness while the antifungal clears the infection; used alone on a fungal rash, a steroid can let the infection spread further.

Miconazole, griseofulvin, luliconazole and fenticonazole are other topical or oral antifungals for similar skin, scalp, nail or mucosal yeast infections, chosen by site and type of infection.

Common questions

Why does a fungal cream need weeks of use?

Fungal skin infections often look better within days, but the fungus can survive under the surface longer. Stopping early is a common reason infections come back, so most creams specify a course length even after symptoms clear.

Do oral antifungals need blood tests?

Short courses, like a single fluconazole dose, generally do not. Longer oral courses of itraconazole, terbinafine or ketoconazole affect the liver in some people, so doctors check liver-function blood tests before starting and periodically during treatment.

Safety essentials

• Tell your prescriber about existing liver disease before starting any oral antifungal; several are processed by the liver and can raise liver enzymes.
• Oral itraconazole, terbinafine and ketoconazole need liver-function monitoring for courses longer than a few weeks; report unusual tiredness, dark urine or yellowing skin straightaway.
• Oral azoles interact with many other medicines, including some heart, cholesterol and anti-seizure drugs, so list everything you take before starting one.
• A steroid-antifungal combination cream is for short, confirmed fungal rashes; using the steroid alone or beyond the course can worsen a fungal infection.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.