Excessive intake of bugleweed by people with thyroid disease or use by healthy people may cause a potentially harmful decrease in thyroid function. Thyroid disease is dangerous and should only be treated under the supervision of a healthcare professional. However, long-term use of bugleweed is considered safe for people with hyperthyroidism.⁶ Bugleweed should not be taken by people with hypothyroidism. Bugleweed should also not be used during pregnancy and breast-feeding.⁷