Despite unlimited access to therapeutic drug monitoring lithium poisoning is still a common and potentially life-threatening but in most cases preventable complication of lithium treatment; however, it is still considered to be the gold standard in the treatment of affective disorders. The necessity of drug monitoring and potential lithium toxicity substantiate the skepticism of many therapists with respect to this often very effective treatment. This therefore limits the use of lithium although the unique therapeutic effects and high efficiency are well known. This retrospective data analysis of risk factors and etiology of lithium poisoning cases identified 58 cases of lithium poisoning, which were treated internally in this hospital between 2010 and 2014. Of the patients 67.2% were female and the majority were classified as chronic poisoning (66.1%). The most relevant patient-related risk factor seemed to be insufficient self-management as 26% of cases of lithium poisoning occurred during febrile infections or exsiccosis. Regarding practitioner-related risk factors, an insufficient consideration of drug interactions, insufficient therapeutic drug monitoring after dose increase and a paucity of experience and knowledge concerning lithium treatment were most relevant. This study illustrates the most important risk factors for lithium poisoning and their frequencies and contributes to raise awareness for this highly relevant topic. These data can help to prevent further cases of lithium poisoning. Furthermore, the results enable a comparison between the actual treatment reality and currently available evidence for the treatment of lithium poisoning.