  We study phase transitions in homogeneous spin-1 Bose gases in the presence
of long-range magnetic dipole-dipole interactions (DDI). We concentrate on
three-dimensional geometries and employ momentum shell renormalization group to
study the possible instabilities caused by the dipole-dipole interaction. At
the zero-temperature limit where quantum fluctuations prevail, we find the
phase diagram to be unaffected by the dipole-dipole interaction. When the
thermal fluctuations dominate, polar and ferromagnetic condensates with DDI
become unstable and we discuss this crossover in detail. On the other hand, the
spin-singlet condensate remains stable in the presence of dipole-dipole
interactions.
