This is a great blog about all things emergency medicine. Great evidenced based articles. This episode they talk about epi dosing for anaphylaxis in patients on beta blockers. Academic Life in EM- Epinephrine
BLUF: Epi in patients with beta blockers does not cause seem to cause unopposed vasoconstriction and hypertensive crisis. Use standard doses of 0.3-0.5mg IM.
ETA: If the patient isn’t responding to epinephrine, give them IV Glucagon. It activates the same cGMP pathway in the cell. BUT you have to give higher doses than the 1mg you might have. 4-6mg, even 10 mg. And you can always go up on the epi dose!