overactive thyroid symptoms/signs - feeling hot (heat intolerance), weight loss, fine tremor, protruding eyes, irritability, palpitations/fast heart rate, neck swelling (goitre), ... to name but a few.
Treatment includes medical management of symptoms e.g. beta blockers to slow heart rate to medical treatment to permanently reduce the gland's activity - radioactive iodine may be used for this purpose, to surgery for removal of part of the thyroid gland to reduce the amount of thyroid hormone you produce to normal.