Formulae for dressed dynamical parameters of semiconductor lasers are derived in the general case of a nonlinear optical gain. Numerical calculations of the dynamical variation of the dressed resonance frequency and damping parameter are presented. A closed form expression for the dressed dynamical parameters is found for the case of direct sinusoidal modulation and a quasi-analytic approach to obtaining detailed features of the laser dynamics is thereby derived. Wider applications of the concepts of dressed dynamics are examined.