IM in anterolateral thigh q 5 - 15 minutes x 3.
Absorption is more rapid and complete in this location relative to SC; IM in deltoid.
Because of the risk for potentially lethal arrhythmias, epinephrine IV should be avoided unless the patient is in cardiac arrest or profoundly hypotensive despite multiple epinephrine IM injections and IV fluids.
Source
Oswalt, M. and Kemp, S. "Anaphylaxis: Office Managment and Prevention" Immunology and Allergy Clinics of North America. May 2007.