All symptoms of hyperthyroidism: what to notice

Common features include a fast or irregular heartbeat, palpitations, shaking hands, feeling unusually warm, sweating, weight loss despite normal or increased appetite, frequent bowel movements, tiredness, muscle weakness, nervousness, irritability and difficulty sleeping.

Excess thyroid hormone speeds up many body processes. People with hyperthyroidism may therefore notice several changes at once, such as heat intolerance alongside sweating, a racing pulse and unexplained weight loss. Other possible signs include a swelling at the front of the neck, hair thinning, fragile nails, itchy skin, thirst, needing to urinate more often, reduced exercise tolerance and changes in menstrual bleeding.

Older adults can have quieter features, including weakness, low mood, loss of appetite or an irregular heartbeat. When Graves' disease is the cause, gritty or dry eyes, light sensitivity, eyelid swelling, prominent-looking eyes or double vision can occur. Symptoms alone cannot confirm the diagnosis because anxiety, infection, medicines and other conditions can cause similar changes.

Arrange a primary-care appointment if several symptoms persist, especially a fast pulse, tremor, heat intolerance or weight change without an obvious explanation. A clinician can review medicines and supplements, examine the neck and heart, and order thyroid blood tests. Do not stop prescribed thyroid medicine or take iodine-containing supplements to treat yourself without clinical advice.

Before the visit, note when symptoms began, whether they are worsening, any pulse readings you already take, changes in weight or menstrual pattern, eye problems, and all medicines or supplements used. This timeline helps distinguish a sustained thyroid pattern from a brief response to stress or illness.

Seek emergency help for a very rapid or irregular heartbeat with chest pain, severe breathlessness, fainting or marked weakness. Fever with severe agitation, confusion, vomiting, diarrhoea or a rapidly worsening heartbeat can signal a dangerous thyroid crisis, particularly in someone with known or untreated hyperthyroidism. Sudden loss of vision, new colour-vision change, or severe eye pain also needs urgent assessment.

Ask which blood tests will assess thyroid function, what could be causing the overactivity, whether your heartbeat needs checking, and whether any current medicine or supplement may interfere with testing. If you have eye symptoms, ask whether you need an eye examination and which changes should prompt urgent care.