Second-order corrections to rate constants, quadratic in the traceless shear stress and proportional in a steady state to the gradient of flow velocity, are calculated for decomposition of dilute gases NO2, N2O, and HI. The approach can be applied, with similar conclusions, to a wide variety of reactions of arbitrary order. The method can be extended to heat flow and diffusive flow of particles. The corrections are found negligible in dilute gases under experimentally accessible conditions, contrary to assumptions often made in extended thermodynamics. Similar effects, in a modified theory taking into account collisional transfer, might possibly be seen in computer studies of steady liquid states far from equilibrium.