Dear Sir/ Madam thanks for writing to us. The prevention for future thromboembolic events needs life long treatment in cases of permanent AF. Hypothyroidism also requires treatment life long in most patients. However these medications need constant monitoring by healthcare provider. Your GP is best person to tell about duration and dose of these drugs depending upon your case. No medication in English system of medicine is devoid of side effects. However mostly the side effects occur in small number of individuals and considered acceptable by medical fraternity. Do consult your doctor if you have any discomfort. But do not stop any medication on your own. Sincerely Sukhvinder