We demonstrate that the condition of vacuum stability severely restricts
scenarios with fermionic WIMP dark matter in the scotogenic model. The sizable
Yukawa couplings that are required to satisfy the dark matter constraint via
thermal freeze-out in these scenarios tend to destabilise the vacuum at scales
below that of the heaviest singlet fermion, rendering the model inconsistent
from a theoretical point of view. By means of a scan over the parameter space,
we study the impact of these renormalisation group effects on the viable
regions of this model. Our analysis shows that a fraction of more than 90% of
the points compatible with all known experimental constraints - including
neutrino masses, the dark matter density, and lepton flavour violation - is
actually inconsistent.Comment: 8 pages, 6 figures; content matches published versio
