Coreg differs from other beta-blockers in that it also has alpha-blocking activity. It is also a non-selective beta-blocker, meaning it has activity on both beta-1 receptors (present in heart tissue) and beta-2 receptors (present in lung airway smooth muscle tissue). Most beta-blockers prescribed for hypertension (e.g., metoprolol, atenolol) are beta-1 selective, meaning they do not affect respiratory smooth muscle. Because of Coreg’s activity on respiratory smooth muscle, it should be avoided in people with severe asthma.