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Dipyrone (metamizol) for management of postoperative pain

Dipyrone is a controversial analgesic. It is used most commonly to treat pain related to surgery, renal colic, cancer and migraine. In many countries (e.g. Russia, Germany, Spain, Mexico, parts of South-America, Asia and Africa) it remains the first line non-opioid analgesic, either by prescription only, as in Germany and Spain, or over the counter. In other countries, it has been banned (e.g. USA, UK, Japan, Canada, parts of Europe and Scandinavia) because of its association with potentially life threatening blood dyscrasias such as agranulocytosis. Cochrane 2010 review. See ‘Background

Treatment specific perioperative issues:

  • The Number Needed to Treat (NNT) of 500 mg dipyrone is 2.4 (1.9 - 3.2) and of 1000 mg 1.6 (1.3 -2.2). This indicates 50% pain relief over 4-6 hours compared with placebo in randomized, double-blind, single-dose studies in patients with moderate to severe postoperative pain Cochrane Library
  • Indirect comparisons of NNTs indicate that oral 500 mg dipyrone has similar efficacy to ibuprofen 400 mg and paracetamol 1000 mg plus codeine 60 mg; it is more effective than paracetamol 1000 mg alone and less effective than etoricoxib 120 mg Cochrane 2010. See Discussion ‘Summary of main results
  • Dipyrone can be given after procedures in the head and neck, oral and maxillofacial operations with moderate pain intensity (NRS 3-5/10). Paracetamol and dipyrone are preferable in comparison to NSAIDs and acetylsalicylic acid due to having a negligible effect on blood coagulation or thrombocytic function German, section, p11; German, p. 16.

Recommendations specific to the treatment

Doses: Single oral dose is 500 – 1000 mg, intravenous dose (IV) 1000 – 2500 mg, by slow infusion over 15 minutes, to a maximum of 4000 (oral) and 5000 (IV) mg/day. German, Table 6.1.2, p80.

Circumstances when the treatment is not recommended

Information about adverse effects of dipyrone after single dose, after surgery, is not readily available as the studies in which its analgesic effects were assessed were underpowered to assess this. Cochrane 2010 review, see 'Summary of main results'.

Dipyrone is associated with agranulocytosis. Use with care in patients with diseases related to the hematopoietic system German section, page 13.

Treatment specific issues related to nursing\monitoring patients

The manufactures recommend that patients should be monitored for blood dyscrasias Cochrane 2010 review, see 'Author's conclusions'


Despite its wide use worldwide, there is little published evidence regarding use of dipyrone for treatment of postoperative pain. The evidence available is not robust, and results should be interpreted with caution. Based on the available literature, a single dose of dipyrone 500 mg appears to provide analgesia which is similar to oral ibuprofen 400 mg when used to treat moderate to severe postoperative pain.

Additional evidence is required to determine whether the benefits of using dipyone outweigh its potential harm Cochrane 2010 review. See Author's conclusions, implications for practice.

Supplementary Reading

  1. Brodner G, Gogarten W, Van Aken H et al Efficacy of intravenous paracetamol compared to dipyrone and parecoxib for postoperative pain management after minor-to-intermediate surgery: a randomised, double-blind trial. Eur J Anaesthesiol. 2011 Feb;28(2):125-32.

  2. Moore RA, Derry S, McQuay HJ, Wiffen PJ. Single dose oral analgesics for acute postoperative pain in adults. Cochrane Database Syst Rev. 2011 Sep 7;(9):CD008659.