Anaphylactic reaction after intravenous dipyrone

SummaryDipyrone (metamizol), a non-opioid analgesic, is widely used for acute and chronic pain management. Although not marketed in all countries because of concerns of possible side effects like agranulocytosis, this potent analgesic is frequently used worldwide.A severe anaphylactic reaction without any cutaneous symptoms was observed after intravenous infusion of dipyrone 1 g. Further symptoms were a short lasting increase in airway pressure and a pronounced generalized oedema. Circulatory arrest required cardiopulmonary resuscitation. Pre-existing β-blockade aggravated poor response to adrenaline. Recovery of the patient was uneventful.Previous case reports demonstrated that symptoms of allergic reaction after dipyrone might vary considerably. Erythema, bronchospasm and eyelid-/angio-oedema might present alone or in combination. Sole cardiovascular collapse produced by extreme generalized oedema and consecutive hypotension occurred after i.v. administration during anaesthesia. Risk factors for severe dipyrone induced allergy are: allergies/intolerability of dipyrone and other non-opioids and bronchial asthma. However, allergic reaction after previous intake of dipyrone without side effects has been described.