Central nervous adverse effects on metoprolol (BELOC-ZOK): A 68-year-old, otherwise healthy male has been taking the ACE-inhibitor enalapril (XANEF, generics) and metoprolol (BELOC-ZOK, generics) for five years for hypertension. After doubling the dose of the beta-blocker, pareidolia initially occurred, for example each cloud in the sky appearing to have a face; this was followed by hallucinations. He subsequently experienced the centre lines on a road wet with rain as "aggressive" during a car ride. On the motorway at high speed, he is overwhelmed by fear and panic. The road seems too narrow for his own car and when overtaking the lane seems to be getting narrower and narrower. The person concerned is afraid of being classed as mentally ill and initially did not confide in anyone about his symptoms which persisted for weeks. One week after stopping metoprolol and doubling the enalapril dose, the symptoms subsided (NETZWERK Report 15.587). The Summary of Product Characteristics (SPC) for metoprolol (e.g. AstraZeneca: BELOC-ZOK SPC, as of June 2009) does mention hallucinations. However, the central nervous adverse events listed are reportedly "of an unusually mild nature and transient". There are no reports of psychoses (KOELLA, W.P.: Eur. J. Clin. Pharmacol. 1985: 28 [Suppl.] S55-S63) and delirium (FISHER, A.A. et al.: Cardiovasc. Drugs Ther. 2002; 16: 161-5). CNS effects of beta-blockers such as depression, nightmares, confusion up to delirium, illusions, paranoid psychosis and reactivation of post-traumatic stress disorders (REEVES, R.R. et al.: Psychosomatics 2003; 44: 440-2) seem to depend on their lipophilia and the possibility of crossing the blood-brain barrier. Metoprolol is considered to occupy a middle position within the group of beta-blockers (McAINSH, J.: Pharmacol. Ther. 1990; 46: 163-97). Many patients do not connect CNS disturbances with taking beta-blockers. Which is why such side effects should be actively inquired about. For instance, a colleague who mentions his own nightmares on beta-blockers to a patient, finds out for the first time about her troubling adverse reaction when she responds, "Oh, so that's why!" (Report 15.589).