What should you know about cold and heat intolerance?

Cold intolerance means feeling chilled when other people are comfortable or needing unusually warm clothing. Heat intolerance may involve excessive sweating, flushing, dizziness, fatigue or feeling unwell in warm surroundings. The pattern matters: a new change with weight change, tremor, diarrhoea, racing heartbeat or marked tiredness needs a different assessment from a lifelong preference for cooler or warmer rooms.

An overactive thyroid can cause heat intolerance and other symptoms, while reduced insulation from low body weight can increase sensitivity to cold. Obesity can make heat dissipation harder. Heat exhaustion is a safety concern when sweating, weakness, headache, nausea or dizziness follows heat exposure.

Keep a brief symptom diary with room conditions, activity, clothing, sweating, sleep, weight change and medicines. Dress in layers for cold, avoid sudden overheating, drink regularly and take breaks in shade or an air-conditioned place during hot weather. Never rely on thirst alone during prolonged heat exposure.

Do not start thyroid medicines or supplements based only on symptoms. A clinician may review your history, examine you and arrange blood tests. If heat exposure causes worsening weakness, move to a cool place and seek help rather than continuing activity.

Seek emergency help for confusion, collapse, seizure, severe breathlessness, chest pain, or very hot skin with a change in alertness. Arrange prompt advice for persistent vomiting, faintness, inability to drink, worsening dizziness, or a new marked change in temperature tolerance. Book a routine review when symptoms persist or interfere with sleep, work or daily activities.

Could my symptoms relate to my thyroid, weight, medicines or another condition? Which observations should I record? Do I need blood tests, and how can I stay safe in hot or cold environments while this is being assessed?