In this work, an efficient treatment strategy for hepatitis C disease using interferon (IFN) has been proposed on the basis of the back-stepping control technique. The basic model of the hepatitis C virus (HCV) has been considered for controller design. To tackle the problem of model parameter variations, the adaptive version of the back-stepping method has been utilized. For applying the proposed treatment, all states should be available while only the viral load is measured. To solve this problem, a nonlinear Luenberger-like observer has been designed to estimate the unmeasured states. In the proposed treatment, limitation of the drug efficacy has been taken into account. Asymptotical stability of the closed-loop HCV control in the presence of observer dynamics and efficacy limitation has been established by the Lyapunov stability theorem. The effectiveness of the proposed treatment has been illustrated by applying it to a HCV model. Simulation results indicate that applying the proposed scheme leads to the reduction of infected cells to the desired level.