  We analyze the validity of perturbative estimations obtained at fixed
dimensions in the study of frustrated magnets. To this end we consider the
five-loop beta-functions obtained within the minimal subtraction scheme and
exploited without epsilon-expansion both for frustrated magnets and for the
well-controlled ferromagnetic systems with a cubic anisotropy. Comparing the
two cases it appears that the fixed point supposed to control the second order
phase transition of frustrated magnets is very likely an unphysical one. This
is supported by the non-Gaussian character of this fixed point at the upper
critical dimension d=4. Our work confirms the weak first order nature of the
phase transition and constitutes a step towards a unified picture of existing
theoretical approaches to frustrated magnets.
