Hepatic sinusoidal obstruction syndrome (HSOS), characterized by hepatomegaly, ascites and hyperbilirubinemia, is caused by toxic injury to hepatic sinusoidal endothelial cells. One major etiology of HSOS in China is the intake of products containing pyrrolizidine alkaloids (PA) such as Tusanqi. The manifestations of patients with HSOS are usually non-specific, presenting with abnormal liver function and portal hypertension. Diagnosis of the disease depends mostly on liver histopathology when clinical and imaging data are not sufficient. A history of Tusanqi intake is mostly important for the diagnosis. Due to a lack of effective, evidence-based treatments for HSOS, avoiding the mistaken use of PA-containing products including Tusanqi is important for the prevention of HSOS.