The continuum of anaphylaxis

The continuum of anaphylaxis

Anaphylaxis often produces signs and symptoms within minutes of exposure to an allergen. However, some reactions may develop later (>30 minutes after exposure) and symptoms not immediately life-threatening can progress rapidly unless promptly treated.8,9 In some cases, a second reaction occurs 1 to 72 hours (usually within 8 hours) after initial recovery despite no further exposure to the trigger. This is known as a biphasic reaction and it can occur in up to 20% of all anaphylactic reactions.5,6,9 Because biphasic reactions are unpredictable and may occur at anytime (including while administering immunotherapy; it is important that observation periods in the office be individualized for each patient), it is important that patients at risk for anaphylaxis carry two doses of epinephrine.5,11