In clinical practice, some patients might not be able or unwilling to provide a thorough history of medication and poison exposure. The aim of this study was to use toxicological analysis to examine the clinical characteristics of patients with acute poisoning whose exposure history was uncertain from a toxicological analysis perspective. This was a retrospective and descriptive study from an institute of poisoning. Patient registration information and test reports spanning the period from April 1, 2020 to March 31, 2022, were obtained. Patients with uncertain exposure histories and who underwent toxicological analysis were included. Clinical manifestations and categories of toxics were analyzed. Among the 195 patients with positive toxicological analysis results, the main causes of uncertain exposure history was disturbance of consciousness (62.6%), unawareness (23.6%) and unwillingness or lack of cooperation (13.8%). The predominant clinical manifestations were disturbed consciousness (62.6%), followed by vomiting and nausea (14.4%) and liver function abnormalities (8.7%). A comparison of clinical manifestations between patients with positive and negative (n=99) toxicological analyses results revealed significantly different proportions of disturbances in consciousness (63% vs. 21%), dizziness (1.5% vs. 5.1%), multi-organ failure (1.5% vs. 7.1%), and local pain (0 vs 4%). The main categories of substances involved were psychiatric medications (23.1%), sedatives (20.5%), insecticides (13.8%), and herbicides (12.8%). The clinical manifestations of acute poisoning in patients with an uncertain exposure history are diverse and nonspecific, and toxicological analysis plays a pivotal role in the diagnosis and differential diagnosis of such patients.