A theoretical study of optical properties in narrow gap semiconductor quantum wells has been developed using an 8x8 Kane Hamiltonian. The interband transition selection rules have been obtained and a detailed description of the interband absorption using Voight and Faraday scattering configurations has been given. Interesting effects produced by the intraband admixture, such as spin-flip transitions, will be discussed. The complementation of measurements using different scattering configurations will be analyzed.