Dehydration and muscle cramps: what to know

Sweating, vomiting, diarrhoea, fever, or simply drinking too little can reduce the fluid available to muscles. Loss of sodium and other electrolytes may also affect the signals that make a muscle contract and relax. A cramp is a sudden, tight, painful contraction, often in the calf, foot, thigh, or hand. Dehydration is one possible contributor; a muscle strain, circulation problem, thyroid disorder, kidney condition, or low vitamin D can also be relevant.

Stop the activity and move to a cool place if heat or exercise was involved. Sip water steadily. If you have had heavy sweating or fluid loss, ask a pharmacist or clinician whether an oral rehydration drink is suitable. Gently stretch the cramped muscle and use light massage; do not force a painful stretch. Once recovered, take regular drink breaks and increase fluids around exercise, while following any fluid restriction prescribed for a heart or kidney condition.

Seek urgent help for confusion, fainting, inability to keep fluids down, severe weakness, very little urine, or a cramp with chest pain or trouble breathing. Arrange a medical review if cramps keep returning, occur without an obvious trigger, disturb sleep repeatedly, or come with leg swelling, numbness, or weakness. A clinician can review medicines, hydration, circulation, and blood tests when needed.

Could a medicine, kidney problem, thyroid problem, circulation issue, or nutritional deficiency be contributing? Which fluids are appropriate for my health conditions? Should I have an electrolyte or blood test? What symptoms should prompt same-day care?