  In this work we study the short-range contributions that induce effective
lepton number violating (LNV) interactions. We obtain a full set of constraints
on the effective short-range couplings from a large variety of low-energy
$|\Delta L|= 2$ processes of pseudoscalar mesons $K, D, D_s, B$, and
$\tau$-lepton. These constraints provide complementary and additional
information to the one obtained from the neutrinoless double-$\beta$
($0\nu\beta\beta$) decay. As expected, the bounds on electron-electron
short-range couplings are the only ones that are strongly constrained by the
$0\nu\beta\beta$ decay. Although weaker, LNV effective couplings with different
flavours are not accessible to $0\nu\beta\beta$ decay and these can be probe by
the $|\Delta L|= 2$ processes in consideration.
