Legs itch when running primarily due to increased blood flow and the dilation of tiny blood vessels (capillaries) in the muscles. This expansion stimulates nearby nerve endings, which the brain interprets as an itching sensation. Additionally, the body releases histamine during exercise, a chemical that causes blood vessels to expand and also contributes to the itching feeling. Other factors like sensitive skin, dryness, sweat irritation, or allergies to detergents or fabrics can worsen the itch. The condition, known as "runner's itch," is common especially when resuming running after a break and often diminishes as the body adjusts to regular exercise.

Causes of Itchy Legs When Running

• Increased blood flow: Running raises heart rate, increasing blood flow and causing capillaries in leg muscles to dilate, stimulating nerves and triggering itchiness.
• Histamine release: Exercise-induced histamine release helps prevent fatigue but also causes blood vessels to expand, enhancing the itchy sensation.
• Sensitive or dry skin: Sweat, detergents, or moisture-wicking fabrics can irritate sensitive skin, contributing to itchiness.
• Exercise-induced skin conditions: Rarely, hives (exercise-induced urticaria), vasculitis, or purpura may cause itching alongside other symptoms.

Managing Runner's Itch

• Regular exercise can help reduce the intensity and frequency of the itch as the body adapts.
• Wearing moisture-wicking clothes and using gentle detergents for workout gear may prevent irritation.
• Moisturizing dry skin before running can also help minimize itchiness.

In most cases, runner's itch is harmless and resolves with consistent exercise and proper skin care.