What are the common causes and effective treatments for heat rash on lower legs?

Common causes of heat rash on the lower legs include excessive sweating, friction from tight clothing, and hot and humid weather. Effective treatments for heat rash on the lower legs include keeping the affected area cool and dry, wearing loose-fitting clothing, using calamine lotion or hydrocortisone cream to reduce itching and inflammation, and avoiding activities that may worsen the rash. In severe cases, a doctor may prescribe topical or oral medications to help alleviate symptoms.