Wear clean, dry athletic supporters and underwear for each workout. This powder discourages recurrence. Your own observation of symptoms. Medical history and physical exam by a doctor. Laboratory studies, including microscopic examination of scraped-off scales suspended in potassium hydroxide liquid.
Recurrences are common.
Contact or allergic dermatitis accompanying jock itch that requires additional treatment, usually with steroid topical applications. Secondary bacterial infection in the affected area. Follow your doctor's instructions. These instructions are supplemental. Bathe with clear water only.