Non-selective beta-blockers, such as propranolol
act on both types of receptors, in both heart and lungs. Propranolol
and other medicines in its class are capable of evoking bronchospasm in people with asthma. Metoprolol is selective, but not entirely so; thus, asthma worsens in some people given this “selective” medicine and you may be one of them.
Your doctor may have prescribed the metoprolol for both relief of the syncope and treatment of your hypertension.