While fungal infections in the armpit are rare, they can become quite severe given the right conditions. Your doctor will need to assess the extent of your condition to prescribe the most effective course of treatment action, but relatively mild fungal infections of the armpit are normally treated using a topical antifungal cream or ointment. Nystatin, tolnaftate, imidazole and naftidine are the most commonly prescribed antifungal creams. Your treatment regimen will likely last about 3 weeks, and you'll need to apply ointment two or three times per day (or as directed). Make sure to follow the application directions closely and continue treatment as long as you're directed. Fungal infections can quickly recur, even when they appear to have cleared up, if you cease treatment too soon.