Hyperthyroidism and heat intolerance

People with an overactive thyroid may feel unusually hot in rooms or weather that others find comfortable. Sweating, warm skin, thirst, restlessness, weight change, loose stools, or a racing heartbeat may occur at the same time. Heat intolerance is a symptom, not a diagnosis: medicines, infection, hormonal changes, obesity, and environmental heat can also affect temperature comfort. Hyperthyroidism is one possible condition to discuss when heat sensitivity is persistent or appears with several symptoms of increased thyroid activity.

Arrange a clinical review if heat intolerance is new or ongoing. A clinician can consider your symptoms, medicines, examination findings, and thyroid blood tests. Until then, drink regularly, choose light clothing, use shade or cool indoor spaces, and reduce strenuous activity during the hottest part of the day. Do not change thyroid medicine without advice. Learn more about [Heat Intolerance](/symptoms/heat-intolerance/) and [Hyperthyroidism](/conditions/hyperthyroidism/).

Move to a cool place and seek urgent help for confusion, fainting, inability to drink, severe weakness, worsening breathlessness, chest pain, or a very fast heartbeat. Hot skin with altered alertness is an emergency. Persistent heavy sweating, vomiting, or dizziness after heat exposure also needs prompt assessment because [Heat Exhaustion](/conditions/heat-exhaustion/) can worsen without timely cooling and fluids.

Could thyroid excess explain my temperature sensitivity? Which other causes should be considered? How should I manage exercise and fluids in hot weather? What symptoms mean I need urgent help?