Sympathomimetics are good for asthma. Sympathetic antagonist drugs (drugs that block the receptor site) are good for high blood pressure and bad for asthma. The sympathetic antagonist will decrease cardiac output and decrease blood pressure, but the sympathetic antagonist also increases bronchial constriction (the opposite of what a sympathetic agonist would do), which will be bad in the case of an asthmatic, as asthma is characterized by bronchial constriction.






