Side effects of hyperthyroidism

Hyperthyroidism means the body is exposed to more thyroid hormone than it needs. This can make the heart beat forcefully or quickly, increase sweating and make warm rooms feel uncomfortable. Some people notice shaking, restlessness, irritability, difficulty sleeping or unplanned weight loss. Faster movement through the gut can cause frequent or loose stools. Night sweats and feeling anxious may overlap with other illnesses, so symptoms do not establish the diagnosis on their own. Learn more about [Hyperthyroidism](/conditions/hyperthyroidism/), [Palpitations](/symptoms/palpitations/) and [Heat Intolerance](/symptoms/heat-intolerance/).

Book a clinical review for persistent palpitations, sweating, bowel changes, sleep difficulty or unexplained weight change. Thyroid blood tests help assess hormone levels, and your clinician may check your pulse, blood pressure and heart rhythm. Take prescribed thyroid medicine exactly as directed and mention decongestants, supplements and other medicines before changing anything. Keep a note of pulse symptoms, bowel frequency, sleep and heat-triggered discomfort. Guidance on [Excessive Sweating](/symptoms/excessive-sweating/) and [Difficulty Sleeping](/symptoms/difficulty-sleeping/) may help you describe the pattern.

Get urgent help for chest pain, fainting, severe breathlessness, a very fast or irregular heartbeat, marked agitation, confusion, high fever or sudden profound weakness. These can indicate a serious escalation of thyroid overactivity or a heart problem. Seek prompt advice if diarrhoea prevents drinking or if sweating and heat exposure lead to dizziness. Call emergency services for collapse or severe breathing difficulty.

Ask which thyroid tests are needed, whether your heart rhythm requires assessment, how soon treatment should improve symptoms, and which medicines or supplements may interfere. Ask for a clear plan if palpitations, diarrhoea or sleep problems worsen.