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An event is serious (FDA MedWatch definition) when the patient outcome is:
* congenital anomaly
* requires intervention to prevent permanent impairment or damage
A 64-year-old man developed urticaria during treatment with dipyrone [metamizole].
The man, who received parenteral dipyrone 2 g and diclofenac to treat painful renal colic, presented after 6 hours with generalised itchy wheals. Despite treatment with oral corticosteroids and antihistamines, his urticaria lasted for 3 days. His skin prick test, intradermal test and single-blind placebo-controlled oral challenge (SBPCOC) with diclofenac and dipyrone was negative. His single-blind placebo-controlled parenteral challenge (SBPCPC) with IM diclofenac was also negative but, SBPCPC with IM dipyrone 2 g caused a maculopapular rash 7 hours after administration showing positive results. He was finally diagnosed with dipyrone-induced urticaria with high parenteral doses of dipyrone.
Author comment: "Our final diagnosis was [dipyrone]-induced urticaria with high parenteral doses of [dipyrone]."
- Prados M, et al. Accelerated-type reactions to high parenteral doses of metamizole in patients who tolerated therapeutic doses of oral metamizole and other NSAIDs. Journal of Investigational Allergology and Clinical Immunology 26: 378-379, No. 6, 2016. Available from: URL: http://doi.org/10.18176/jiaci.0098 - SpainCrossRefPubMedGoogle Scholar