A life-threatening systemic hypersensitivity reaction to contact with an allergen; it may appear within minutes of exposure to the offending substance.
Manifestations include respiratory distress, pruritus, urticaria, mucous membrane swelling, gastrointestinal disturbances (including nausea, vomiting, abdominal pain, and diarrhea), and vascular collapse. Virtually any allergen may trigger an anaphylactic reaction, but among the more common agents are proteins such as antisera, hormones, pollen extracts, Hymenoptera venom, and foods; drugs (especially antibiotics); and diagnostic agents such as IV contrast material. Atopy does not seem to predispose to anaphylaxis from penicillin or venom exposures.
Time to onset is variable, but symptoms usually occur within seconds to minutes of exposure to the offending antigen:
Made by obtaining history of exposure to offending substance with subsequent development of characteristic complex of symptoms.
The medicines that can be thought of use are:-