Fatigue and heat intolerance: what to know

Heat intolerance means warmth feels unusually difficult to manage, sometimes with heavy sweating, dizziness, flushing or a fast heartbeat. Heat exhaustion can develop when sweating and fluid loss leave you weak, nauseated or light-headed. Hyperthyroidism can make the body run hot and may bring tremor, weight change, diarrhoea or a racing pulse. Obesity can make cooling harder because the body has more difficulty releasing heat. The combination is not enough to determine the cause.

Move to shade or an air-conditioned place, loosen extra clothing and sip fluids if you are alert and able to swallow. Avoid strenuous activity and alcohol while recovering from heat exposure. Write down when tiredness and heat sensitivity occur, your temperature if measured, sweating, bowel changes, weight changes and medicines. A clinician can examine you and decide whether blood tests, including thyroid testing, are appropriate.

Call emergency services for confusion, collapse, seizures, severe weakness, inability to drink or a very high temperature after heat exposure. Seek prompt care for persistent vomiting, faintness, worsening symptoms or signs of dehydration. Book a medical review when heat intolerance and fatigue continue indoors or recur without a clear heat trigger.

Could a thyroid problem, medicine or fluid loss explain this pattern? Which temperature or circulation symptoms require urgent help? Should I change activity, fluid intake or timing of medicines in hot weather?