Hyperthyroidism and muscle cramps

An overactive thyroid can increase the body's energy use and contribute to muscle fatigue or weakness. Sweating, diarrhoea and reduced fluid intake may add to dehydration, which can make cramping more likely. Cramps can affect the calves, feet or other muscles, often after activity or at night. They are not specific to thyroid disease: exertion, medicines, nerve problems and changes in body salts can also be involved. The pattern and accompanying symptoms help a clinician decide what to investigate.

During a cramp, stop the activity, gently stretch the muscle and use light massage. Drink fluids regularly, especially after sweating or loose stools, unless you have been told to restrict fluids. Note the muscle involved, timing, triggers, duration and any weakness between episodes. Avoid starting electrolyte or mineral supplements without professional advice. Arrange assessment if cramps recur, disturb sleep or occur with progressive weakness. Information about [Hyperthyroidism](/conditions/hyperthyroidism/) can provide useful context.

Seek urgent help if cramping comes with severe weakness, inability to walk, fainting, confusion, chest pain, difficulty breathing or a sustained racing heartbeat. Prompt assessment is also sensible after persistent vomiting or diarrhoea, because fluid and salt disturbances may become serious. A sudden swollen, red or very painful limb needs urgent evaluation for causes unrelated to the thyroid.

Ask whether thyroid testing, kidney tests or blood salts are appropriate, whether a current medicine can contribute, how much fluid is suitable for you, and which strength or exercise changes are safe.