Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used as analgesics and antipyretics in Western countries. Gastrointestinal (GI) disorders are common side effects of NSAIDs and other drugs. This study investigated the correlation between chronic use of these substances and GI lesions by analyzing postmortem blood and hair samples from autopsy cases. This study included 268 hair and blood samples from autopsy cases. Deceased individuals with GI lesions were selected for the case group (n = 132) and those without any GI lesions were placed in the control group (n = 136). Collection of the samples took place from 2008 until 2010 at the Institute of Legal Medicine and Forensic Sciences, Charité-Universitätsmedizin Berlin, Germany. HPLC-DAD was used to analyze the blood samples while hair samples were analyzed using LC-quadrupole-time-of-flight-MS. The proximal 0-6 cm hair segment was analyzed. The full length of shorter hair samples was analyzed when longer segments were unavailable. Method validation was performed according to the guidelines of the German Society of Toxicological and Forensic Chemistry (GTFCh). Twenty-three per cent of the case group blood samples included one or more NSAIDs while 19 % of the control group blood samples included one or more NSAIDs. In contrast, the hair analysis results demonstrated that samples from the control and case group differed significantly; 67 % of the case group tested positive for one or more NSAIDs while 38 % of the control group tested positive for one or more NSAIDs. Hair analysis results provided a strong indication of a relationship between frequent NSAID consumption and GI lesions.