What is calf pain? Calf pain is any feeling of discomfort in the fleshy tissue on the back side of the lower leg, from below the knee to above the ankle. Your calves are made up of muscles, tendons, ligaments, nerves, and blood vessels, all of which are subject to injury, infection, or other conditions that can be painful. Calf pain may last briefly or be constant. It may affect your entire calf or only a localized area. Your pain may feel dull and achy, throbbing, piercing, or tingling. Pain-like sensations that are often described as pins-and-needles, prickling, or burning are called paresthesias. Calf pain may be simply irritating and uncomfortable or so debilitating that you can’t put weight on your leg or walk. Calf pain can arise from a variety of conditions ranging from accidental trauma to nerve conditions. Calf pain in the absence of trauma or other symptoms is commonly due to a muscle cramp, also called a “charley horse.” However, there are more serious conditions that lead to calf pain, such as peripheral artery disease. Calf pain can be due to deep vein thrombosis (a blood clot in the leg), which is a serious and life-threatening condition. The blood clot can break loose and cause a pulmonary embolism in the lung, a heart attack, or a stroke. If you, or someone you are with, are experiencing calf or leg pain after mild exercise or exertion, or if you are experiencing pain, swelling, redness, and warmth in the calf, seek immediate medical care (call 911).