Nightmares and depression on dronedarone (MULTAQ): A 71-year-old man was taking the amiodarone analogue dronedarone (MULTAQ) for the prevention of relapses of recurrent atrial fibrillation following cardioversion. At the same time, he started anticoagulation therapy with phenprocoumon (MARCUMAR, generic). After two and a half weeks, he reported severe nightmares for the first time, thrashing around during them according to his wife (NETZWERK report 15.849). To date, there are no reports of nightmares as a side effect of dronedarone or phenprocoumon in the information for healthcare professionals or in the literature (Sanofi-Aventis: MULTAQ Summary of Product Characteristics dated Jan. 2011; MEDA Pharma: MARCUMAR Summary of Product Characteristics, dated Dec. 2010). They occur commonly on amiodarone (CORDAREX, generic) (Sanofi-Aventis: CORDAREX Summary of Product Characteristics, dated Nov. 2008). An interaction with bisoprolol (CONCOR, generic), which the patient had been taking for quite a long time, is also conceivable: it can trigger nightmares in rare cases and its level can be increased by dronedarone. The Federal Institute for Drugs and Medical Devices (BfArM) has received one report of a suspected case of nightmares on dronedarone (BfArM: letter dated 15 March 2011). A 66-year-old man developed a different nervous system disorder while taking dronedarone for several months: besides experiencing increasing muscle and joint pain as well as headaches, nausea and malaise, he became depressed. The symptoms subsided after discontinuation (NETZWERK report 15.836). Depression and pain of this kind have not yet been described as a side effect of dronedarone either. The BfArM has received one report of depression on dronedarone, six of muscle pain, four of joint pain and three of headache (BfArM: letter dated 15 March 2011).