FIELD: medicine. SUBSTANCE: invention proposes antibody-base medicinal agent comprising activated form of supersmall doses of monoclonal, polyclonal or natural antibodies raised to interferon obtained by multiple successive dilution and external effect, mainly, by homeopathic technology. Invention relates also to method of treatment of pathological syndrome using activated form of supersmall doses of antibodies raised to alpha-, beta- or gamma-interferon in mixture of different, mainly hundredth, homeopathic dilutions. Invention provides development of effective preparation with immunotropic activity and method of treatment of infectious diseases, among them, viral etiology. Invention can be used for treatment and prophylaxis of acute and chronic infectious diseases, mainly viral etiology, and for immunomodulating effect offering. EFFECT: improved method of treatment, enhanced effectiveness of agent. 5 cl, 2 tbl, 9 ex
