When to worry about unintentional weight loss with hyperthyroidism

Excess thyroid hormone speeds up many body processes and can increase appetite while the body uses energy rapidly. Heat intolerance, sweating, tremor, anxiety, frequent bowel movements, and muscle weakness may occur alongside the weight change. Weight loss can continue if hyperthyroidism is untreated or if treatment is not yet balanced. Other illnesses and medication effects can also affect weight, so symptoms and thyroid testing need to be considered together.

Contact your GP or thyroid team for a review of symptoms, medicines, pulse, and thyroid blood tests. Take prescribed antithyroid treatment exactly as directed and do not change the dose on your own. Note your appetite, bowel pattern, palpitations, sleep, and exercise tolerance. Eat regular nourishing meals and drink enough fluid, especially if sweating or diarrhoea is present.

Get emergency help for chest pain, severe breathlessness, fainting, confusion, or a very fast or irregular heartbeat with feeling unwell. Seek prompt medical advice for high fever, marked agitation, repeated vomiting, or rapidly worsening weakness. These symptoms can indicate that the body is being affected significantly by excess thyroid hormone or another urgent problem.

Ask whether your thyroid levels and treatment need adjustment, when testing should be repeated, and how to manage palpitations or diarrhoea. Ask which symptoms should trigger same-day advice and whether nutrition support is needed.