A general method is formulated for the calculation of the phonon spectrum of anharmonic metals by applying the pseudopotential method. On the basis of the recently developed theory of anharmonic crystals, the frequencies of selfconsistent phonons and their damping in the adiabatic approximation are obtained, taking into account the effective cubic anharmonic interactions. The importance of indirect many body forces in anharmonic metals is stressed. The three body interactions are explicitly taken into consideration.