What causes muscle cramps?

A muscle may cramp after overuse, prolonged sitting, a new workout or loss of fluid through sweating. Heat Cramps are associated with exertion in hot conditions. Dehydration can alter the fluid balance around muscles and nerves. A strain may cause local spasm and tenderness. Repeated cramps can also occur with reduced blood flow from Peripheral Arterial Disease, reduced muscle mass in Sarcopenia, an underactive thyroid, kidney disease or low vitamin D.

The location, activity, medicines and pattern matter. A night-time calf cramp has a different context from cramps that begin during walking and ease with rest.

Stop the activity and gently stretch the affected muscle. For a calf cramp, straighten the leg and draw the toes towards you; gentle massage may help. Sip fluids, move to a cooler place after heat exposure, and resume activity gradually. Do not force a painful stretch or start mineral supplements without advice, because the cause may not be a deficiency and supplements can interact with treatment.

Book an assessment if cramps are frequent, severe, spreading, disturbing sleep or accompanied by weakness, numbness, swelling or a change in walking distance. Seek urgent care for a cramp with a cold or pale limb, severe swelling, fainting, confusion, very dark urine or signs of serious heat illness. A clinician may review medicines and check circulation, nerves or relevant blood tests.

Ask whether your cramps fit dehydration, heat exposure, strain, circulation problems or a medical condition. Bring details about timing, affected muscles, exercise, fluid intake and medicines. Ask whether stretching, hydration changes or tests are appropriate, and whether a supplement could be unsafe for you.