Fungal infections are treated with antifungal medications, and the right approach depends entirely on where the infection is and how deep it goes. A surface-level skin infection might clear up with a drugstore cream in a few weeks, while a fungal infection in the bloodstream requires hospital-level treatment with intravenous drugs. Here’s what treatment looks like across the most common scenarios.
How Antifungal Drugs Work
Fungi have a unique cell membrane built around a fatty molecule called ergosterol. This is the key vulnerability that most antifungal drugs exploit. The three main classes of antifungals each attack fungi differently:
- Azoles block the production of ergosterol, which weakens the fungal cell membrane and stops the organism from growing. This is the most widely used class, covering everything from over-the-counter creams to prescription pills.
- Polyenes bind directly to ergosterol in the membrane, punching holes in the fungal cell and killing it. These tend to be more powerful and are reserved for serious infections.
- Echinocandins work differently altogether, targeting the fungal cell wall rather than the membrane. They’re used primarily in hospitals for invasive infections.
Because human cells don’t contain ergosterol or fungal-type cell walls, these drugs can target fungi without destroying your own tissue. That said, they aren’t without side effects, especially at higher doses or over longer treatment courses.
Treating Skin, Foot, and Groin Infections
Most common fungal infections (athlete’s foot, jock itch, ringworm, and mild yeast infections) respond well to topical antifungal creams, lotions, or ointments applied directly to the skin. Clotrimazole is one of the most widely available options, sold under brand names like Lotrimin and Desenex. You can buy it without a prescription at virtually any pharmacy.
Topical treatments typically need to be applied once or twice daily for two to four weeks, depending on the location and severity of the infection. The skin may look better before the fungus is fully gone, so finishing the full course matters. If a topical cream doesn’t work after several weeks, a doctor may prescribe a stronger cream or switch to an oral antifungal.
Treating Nail Fungus
Nail infections are notoriously stubborn because the fungus lives underneath the nail plate, where creams can’t easily reach. Oral antifungal medication is the standard treatment. Terbinafine, one of the most commonly prescribed options, is taken once daily for 6 weeks for fingernail infections and 12 weeks for toenail infections.
Even after the medication course ends, you won’t see results immediately. The infected nail has to grow out and be replaced by healthy nail, which can take several months for fingernails and up to a year for toenails. This long timeline is normal and doesn’t mean the treatment failed. Some people need a second course if the infection is particularly deep or returns after the nail grows back.
Treating Serious Internal Infections
Invasive fungal infections, where fungi enter the bloodstream, lungs, or organs, are a different category entirely. These occur most often in people with weakened immune systems: those undergoing chemotherapy, organ transplant recipients on immune-suppressing drugs, or people with advanced HIV. Treatment happens in a hospital setting and involves intravenous or high-dose oral antifungals.
For bloodstream infections caused by Candida (the most common culprit), doctors typically start with either an echinocandin or a high initial dose of an oral azole, then step down to a lower maintenance dose. In patients with severely compromised immune systems, a polyene delivered intravenously is often the first choice because of its broad and potent activity. Treatment duration varies widely, from a couple of weeks to several months, depending on how the infection responds and the patient’s overall health.
Liver Monitoring During Oral Treatment
All commonly prescribed oral antifungals carry some risk of liver irritation. For most of them, you’d only need liver testing if you develop symptoms like unusual fatigue, dark urine, yellowing skin, or abdominal pain during treatment. Your doctor would then check liver enzyme levels and decide whether to continue or stop the medication.
The exception is ketoconazole, an older oral antifungal with a higher risk of liver problems. For this drug, liver function testing before starting treatment and at regular intervals throughout is standard practice. Ketoconazole has largely been replaced by newer, safer options for most infections, but it’s still prescribed in certain situations. If you’re taking any oral antifungal for more than a few weeks, it’s worth knowing what liver-related warning signs to watch for.
The Growing Problem of Resistant Fungi
Just like antibiotic-resistant bacteria, some fungi are becoming harder to treat with standard medications. The World Health Organization published its first-ever fungal priority pathogens list to flag the species of greatest concern, and the CDC tracks resistant fungi as an emerging public health threat.
The most alarming example is Candida auris, a species that emerged in healthcare facilities around the world over the past couple of decades. C. auris is often resistant to multiple drug classes, and some cases have been resistant to all three major classes of antifungals, leaving very few treatment options. It also spreads easily in hospitals and nursing homes, making it particularly dangerous for vulnerable patients. Certain strains of Aspergillus and some dermatophytes (the fungi behind ringworm and athlete’s foot) are also showing increasing resistance.
For everyday fungal infections, resistance isn’t something most people need to worry about. But it does mean that finishing your full course of antifungal treatment matters. Stopping early when symptoms improve gives surviving fungi a chance to develop resistance, making future infections harder to treat.