Paradoxical reaction to epinephrine induced by beta-blockers in an anaphylactic shock induced by penicillin.

Increased risk of severe and resistant anaphylactic shock is a rare and not widely known adverse effect of beta-blocker treatment. It is illustrated in a case of refractory anaphylactic shock occurring in a 47-year-old woman who received beta-blockers. Actually, beta-blockers increase the release of anaphylactic mediators, decrease the cardiovascular compensatory changes to the anaphylactic shock and promote paradoxical reflex vagotonic effects when using epinephrine.