BACKGROUND: Heavy bleeding and pain are the most common reasons why women discontinue IUDs. Non-steroidal anti-inflammatory drugs, which inhibit prostaglandin synthesis, have been shown to be effective in reducing menstrual bleeding and pain in women without IUDs. OBJECTIVES: This review summarizes all randomized controlled trials studying use of nonsteroidal anti-inflammatory drugs for treatment of bleeding or pain associated with IUD use. Trials of prophylactic use of these drugs around the time of IUD insertion were also included. SEARCH STRATEGY: We performed searches of PubMed, CENTRAL, POPLINE, EMBASE, LILACS, and CINAHL for relevant trials. We also wrote to the authors of all trials identified to seek other published or unpublished trials. SELECTION CRITERIA: We included all randomized controlled trials in any language that tested one or more nonsteroidal anti-inflammatory drugs for treatment or prevention of bleeding or pain associated with IUD insertion or use. DATA COLLECTION AND ANALYSIS: Two authors independently abstracted data from relevant trials, and we entered data into RevMan for analysis. MAIN RESULTS: We found 15 trials from 10 countries; the total number of participants was 2702. Nonsteroidal anti-inflammatory drugs (naproxen, suprofen, mefenamic acid, ibuprofen, indomethacin, flufenamic acid, alclofenac, and diclofenac) were effective in reducing menstrual blood loss associated with IUD use. This held true for women with and without complaints of heavy bleeding. Similarly, these drugs were effective in reducing pain associated with IUD use. In contrast, prophylactic use of nonsteroidal anti-inflammatory drugs had mixed results; studies with ibuprofen found no effect on pain after insertion on IUD discontinuation. No important differences emerged in the one trial comparing the effect of different NSAIDs on bleeding. AUTHORS' CONCLUSIONS: Nonsteroidal anti-inflammatory drugs reduce bleeding and pain associated with IUD use. NSAIDs should be considered first-line therapy; if NSAIDs are ineffective, tranexamic acid may be considered as second-line therapy. Prophylactic ibuprofen administration with the first six menses after insertion appears unwarranted.