  We continue a previous study about the infrared loop effects in the
$D$-dimensional de Sitter space for a real scalar $\phi^4$ theory from the
complementary series whose bare mass belongs to the interval
$\frac{\sqrt{3}}{4}\, \left(D-1\right) < m \leq \frac{D-1}{2}$, in units of the
Hubble scale. The lower bound comes from the appearance of discrete states in
the mass spectrum of the theory when that bound is violated, causing large IR
loop effects in the vertices. We derive an equation which allows to perform a
self--consistent resummation of the leading IR contributions from all loops to
the two-point correlation functions in an expanding Poincar\'{e} patch of the
de Sitter manifold. The resummation can be done for density perturbations of
the Bunch--Davies state which violate the de Sitter isometry. There exist
solutions having a singular (exploding) behavior and therefore the backreaction
can change the de Sitter geometry.
