Common causes of pulmonary "arterial" hypertension (PAH) include HIV, scleroderma and other autoimmune disorders, cirrhosis and portal hypertension, sickle cell disease, congenital heart disease, thyroid diseases, and others. Use of weight loss pills such as Fen-Phen, Aminorex, fenfluramine (Pondimin), and phentermine led to the development of PAH in the past.