According to the 2014 European Association for the Study of the Liver (EASL) and the American Association for the Study of the Liver (AASLD) joint recommendations, the term «hepatic encephalopathy» is defined as brain dysfunction associated with liver failure and/or porto-systemic blood shunting. In the 2022 EASL guidelines is noted that patients with suspected hepatic encephalopathy should undergo a standardized diagnostic examination that includes a list of necessary laboratory and instrumental examinations. In guidelines is hightlitened the role of ammonium, the level of which should be measured in patients with acute hepatic encephalopathy and liver disease, as its normal level casts doubt on the hepatic encephalopathy diagnosis (level of evidence 4, strong recommendation). The main principle underlying the treatment of hepatic encephalopathy is reducing the ammonium level in the blood by reducing its production and its accelerated removal from the body. One of the ways to remove ammonium from the liver by stimulating the synthesis of urea by residual hepatocytes and/or increasing the synthesis of glutamine in the muscles is the use of L-ornithine-L-aspartate (original drug Hepa-Merz, Merz Pharma GmbH&Co. KGaA), the effectiveness of which has been shown in a series of clinical trials. Thus, according to modern international recommendations, an important pathogenetic link in the development of hepatic encephalopathy is hyperammonemia, the correction of which will lead to the normalization of the neuropsychiatric condition of patients.