“Fainting spells” is not a common presenting symptom in hypothyroidism. Hence if a case of hypothyroidism complaints of “fainting spell” I would definitely investigate further for any coexisting medical condition that could explain the symptom. read more
Also low blood pressure may cause the same symptoms. In addition to getting your hypothyroidism under control, consider taking a magnesium supplement , which may help both the heart issues and other symptoms of hypothyroidism. Also dehydration could cause fainting and lightheadedness. read more
Endocrine problems, such as an underactive thyroid (called hypothyroidism), overactive thyroid (called hyperthyroidism), adrenal insufficiency (called Addison's disease), low blood sugar levels, and in some cases, diabetes, may lead to hypotension and hence lightheadedness and an off balance feeling. read more