The intersubband (ISB) dynamics of spin orientated carriers generated in undoped quantum wells by circularly polarized interband excitations is analyzed theoretically. It is shown that short THz pulses in resonance with the lowest conduction ISB transition can be used to switch the spin orientation in a given subband without changing the total subband occupation. For longer ISB pulses a periodic modulation of the spin orientation is found. However, when the Coulomb interaction is taken into account the total subband density is typically also modulated which differs from expectations based on calculations in a three band model of non-interacting particles. The dependence on the ratio of the subband masses is discussed as well as the observability of these effects in pump-probe type measurements.