What should you know about exogenous hyperthyroidism?

Exogenous hyperthyroidism occurs when thyroid hormone from medicine or another outside source is higher than your body needs. It differs from the thyroid gland making too much hormone, although the effects can feel similar.

Extra thyroid hormone can speed up the heart, bowel and nervous system. You may notice palpitations, feeling anxious, difficulty sleeping, excessive sweating, heat intolerance or diarrhoea. These symptoms do not prove the cause; prescribed dose, supplements and other thyroid products all need review.

Arrange a clinical review and take the exact medicine names, strengths and schedule with you. Include supplements, weight-loss products and medicines obtained elsewhere. Do not change or stop thyroid replacement on your own, particularly after thyroid surgery or treatment for hypothyroidism. A clinician may repeat thyroid blood tests and adjust the source of hormone.

Seek urgent help for chest pain, fainting, severe breathlessness, confusion or a very fast or irregular heartbeat. Contact a clinician promptly if symptoms are worsening, you cannot keep medicines down, or palpitations continue at rest.

Ask which product is causing the excess hormone, when testing should be repeated, what dose changes are appropriate, and which symptoms should trigger urgent assessment.