  We analyze the isospin-breaking corrections to quark condensates within
one-loop SU(2) and SU(3) Chiral Perturbation Theory including $m_u\neq m_d$ as
well as electromagnetic (EM) contributions. The explicit expressions are given
and several phenomenological aspects are studied. We analyze the sensitivity of
recent condensate determinations to the EM low-energy constants (LEC). If the
explicit chiral symmetry breaking induced by EM terms generates a
ferromagnetic-like response of the vacuum, as in the case of quark masses, the
increasing of the order parameter implies constraints for the EM LEC, which we
check with different estimates in the literature. In addition, we extend the
sum rule relating quark condensate ratios in SU(3) to include EM corrections,
which are of the same order as the $m_u\neq m_d$ ones, and we use that sum rule
to estimate the vacuum asymmetry within ChPT. We also discuss the matching
conditions between the SU(2) and SU(3) LEC involved in the condensates, when
both isospin-breaking sources are taken into account.
