Hyperthyroidism cardiovascular effects

Thyroid hormone increases the body's sensitivity to adrenaline and changes how strongly and quickly the heart contracts. This can cause a racing pulse, pounding beats or skipped beats, also called palpitations. Some people develop an irregular rhythm, so a clinician may check the pulse and perform an electrocardiogram. Blood pressure can change as the heart pumps more forcefully. Symptoms may occur alongside heat intolerance, excessive sweating, difficulty sleeping or feeling anxious. These symptoms can have other causes, so they do not confirm hyperthyroidism on their own.

Treatment focuses on the thyroid problem and, when suitable, may include medicine to ease a rapid heartbeat while the underlying cause is assessed. Read more about [Hyperthyroidism](/conditions/hyperthyroidism/).

Arrange a medical assessment if you have persistent palpitations, a fast resting pulse, new breathlessness or unexplained tiredness. A clinician may ask about medicines and supplements, examine your neck and heart, and order thyroid blood tests. Keep a note of when symptoms start, how long they last, and whether caffeine, exertion or stress appears to trigger them. Do not change prescribed thyroid medicine without advice. Limiting stimulants and maintaining fluids may help while you await assessment, but these measures do not treat excess thyroid hormone.

Seek emergency care for chest pain, fainting, severe breathlessness, confusion, or a very fast or irregular heartbeat that does not settle. A high fever with marked agitation, vomiting or severe weakness also needs urgent attention because severe, untreated thyroid overactivity can become dangerous. If symptoms are milder but recurring, book a prompt appointment rather than relying on self-monitoring.

Ask: Could my symptoms be related to thyroid hormone excess? Do I need an electrocardiogram or other heart checks? Which medicines, supplements or drinks should I avoid? How will we monitor my thyroid levels and heart rate?