A method of treating a pathological syndrome includes administration of an activated form of ultra-low doses of antibodies to an antigen, wherein said activated form is obtained by repeated consecutive dilution combined with external impact, and the antigen is a substance or a pharmaceutical agent exerting influence upon the mechanisms of formation of this particular pathological syndrome.Pharmaceutical agent for treating a pathological syndrome contains activated form of ultra-low doses of monoclonal, polyclonal or natural antibodies to an antigen, wherein said activated form is prepared by means of repeated consecutive dilution and external treatment, predominantly based on homeopathic technology, and said antigen is a substance or a drug acting as a direct cause of the pathological syndrome or involved in regulation of mechanisms of its formation. At that, activated forms of ultra-low doses of antibodies are raised against antigens of exogenous or endogenous origin, against autologous antigens, fetal antigens; anti-idiotypic antibodies are used too.