Serious adverse drug reactions with tramadol reported to the French pharmacovigilance database between 2011 and 2015

Tramadol is an opioid and a serotonin reuptake inhibitor drug. It is approved for moderate to severe pain in adults. The aim of this study was to assess tramadol safety through a national pharmacovigilance study in France since dextropropoxyphen withdrawal in 2011. We described all serious adverse drug reactions (SADRs) reported with tramadol in adults in the French National PharmacoVigilance Database from August 1st, 2011 to December 31st, 2015. We identified 1512 SADRs during the study period. The most frequently reported SADRs were neurological (29.4%, including troubles of consciousness [13.2%] and seizures [6.7%]), psychiatric (22.8%, including confusions [14.6%] and hallucinations [7.3%]) and gastrointestinal (17.0%, mostly nausea and vomiting [9.6%]). Unexpected SADRs were also reported: hyponatremia, cholestatic hepatitis, serotonin syndrome. This study demonstrates new unexpected hepatic and metabolic SADRs. Tramadol alone can induce serotonin syndrome in overdose situations.