Metoprolol tablets are a beta-blocker and can cause a series of side effects when taken in excess: 1) sinus bradycardia and varying degrees of atrioventricular block; 2) hypotension and even hypotensive shock; 3) bronchial asthma; 4) heart failure if taken excessively. Patients may experience central nervous system side effects such as insomnia and excessive dreaming. 6. Excessive use of metoprolol tablets may also induce angina pectoris. 7.