[Anaphylaxis can be life-threatening, treatment must be initiated promptly]

Anaphylaxis is an acute, severe, systemic hypersensitivity reaction and is potentially fatal. It is sudden and almost always unanticipated, and it involves more than one organ system. Symptom onset varies widely from within seconds to a few hours, but usually occurs within 30 minutes of exposure to the trigger. Early diagnosis and prompt initiation of treatment is important and the diagnosis should be established only when the diagnostic criteria are met. Any delay in the recognition of the initial signs and symptoms can result in a fatal outcome, either because of airway obstruction or circulatory collapse. Adrenaline is the drug of choice and should be immediately administered intramuscularly with suspected reaction.