Smoking and hyperthyroidism: what should you know?

Hyperthyroidism increases the body's metabolic activity. Nicotine can stimulate the heart and nervous system, which may add to a racing heartbeat, tremor, restlessness, or difficulty sleeping. Most people with hyperthyroidism notice a group of symptoms rather than one isolated sign, such as [Excessive Sweating](/symptoms/excessive-sweating/), heat intolerance, diarrhoea, or feeling anxious. Smoking is especially relevant if thyroid eye disease is present; tell your clinician about eye pain, redness, swelling, or changes in vision. See [Hyperthyroidism](/conditions/hyperthyroidism/) for condition-focused information.

Arrange thyroid blood tests and review your symptoms with a clinician rather than assuming every racing heartbeat is caused by smoking. Take antithyroid treatment exactly as prescribed and ask before using supplements or changing doses. Make a quit plan with support for cravings, avoid excess caffeine if it worsens palpitations, and keep cool and hydrated during sweating episodes. Note sleep, bowel changes, heat sensitivity, and heartbeat patterns so your clinician can judge whether treatment needs adjustment.

Seek urgent help for chest pain, fainting, severe breathlessness, new confusion, marked agitation, or a very fast or irregular heartbeat that does not settle. Contact your thyroid team promptly for worsening [Palpitations](/symptoms/palpitations/), persistent [Difficulty Sleeping](/symptoms/difficulty-sleeping/), or escalating sweating, diarrhoea, or heat intolerance. Do not stop thyroid medicine because symptoms improve without medical advice.

Ask whether smoking is affecting your symptoms or eyes, how often thyroid tests are needed, what to do if a dose is missed, and which quit-smoking medicines are suitable. Ask which heartbeat or eye symptoms require same-day assessment.