Heat-related muscle cramps: what to know

Cramps often affect the calves, thighs, arms, or abdomen during or after hard work in hot conditions. Sweat removes water and salts, while tired muscles are more likely to tighten suddenly. The pain may come in waves, and the muscle can feel firm or visibly contracted. Heat cramps are different from a muscle injury, although both can hurt. Repeated episodes without heat exposure may need another explanation, such as [Dehydration](/conditions/dehydration/) or [Hypothyroidism](/conditions/hypothyroidism/).

Stop exercising and move into shade or air conditioning. Gently stretch the affected muscle and hold it until the spasm eases; light massage may help. Sip water or an appropriate rehydration drink if you are alert and not vomiting. Avoid returning to strenuous activity while cramping, weak, or dizzy. Do not take salt tablets unless a clinician has advised them. People with kidney disease or fluid restrictions should ask for individual guidance, because excess fluid or electrolytes may be harmful.

Get urgent help for confusion, fainting, seizure, severe weakness, chest symptoms, or inability to drink. Arrange prompt assessment if cramps are severe, keep returning after rest and cooling, last longer than expected, or occur with very dark urine or marked swelling. Seek advice before using electrolyte products if you have [Chronic Kidney Disease](/conditions/chronic-kidney-disease/).

Ask whether medicines, fluid restrictions, circulation problems, or nutrition could contribute. Mention the muscles involved, your activity and heat exposure, how much you were sweating, what you drank, and whether weakness continued after the cramp stopped.