Hyperthyroidism and heart failure

Excess thyroid hormone can make the heart beat faster and more forcefully. Over time, that extra demand may worsen an existing heart condition or contribute to rhythm problems and reduced pumping ability. Breathlessness, tiredness, reduced exercise tolerance, ankle swelling, or a racing or irregular heartbeat deserve medical review. These symptoms do not prove heart failure, and hyperthyroidism can produce similar sensations through other effects on the body. A clinician may need to assess both thyroid function and heart function.

Seek medical care promptly if you have symptoms suggesting excess thyroid activity together with new breathlessness, swelling, or reduced stamina. Assessment may include an examination, thyroid blood tests, an electrocardiogram, and other heart tests chosen for your symptoms. Continue prescribed medicines unless the prescriber changes them, and tell the care team about all medicines and supplements. Avoid self-treating a fast heartbeat with someone else’s medication. Information about [Hyperthyroidism](/conditions/hyperthyroidism/) and [Palpitations](/symptoms/palpitations/) can help you prepare for the appointment.

Call emergency services for severe or sudden breathlessness, chest pain, fainting, blue or grey lips, new confusion, or a rapid irregular heartbeat with weakness or dizziness. Urgent assessment is also needed if swelling and breathlessness rapidly worsen or you cannot lie flat comfortably. Early review matters because thyroid excess and heart strain can reinforce one another.

Could my symptoms reflect thyroid-related heart strain, a rhythm problem, or another cause? Which tests will check thyroid and heart function? Should any current medicine be changed? What symptoms should trigger emergency help?