In this paper we show how effective parameters such as effective binding energies can be defined for a proton in the combined nuclear‐Coulomb potential, including also the target potential, in the case in which the proton is bound in a nucleus which is partner of a nuclear reaction. Using such effective parameters the proton behaves similarly to a neutron. In this way some unexpected results obtained from dynamical calculations for reactions initiated by very weakly bound proton halo nuclei can be interpreted. Namely the fact that stripping dominates the nuclear breakup cross section which in turn dominates over the Coulomb breakup even when the target is heavy at medium to high incident energies. Our interpretation helps also clarifying why the existence and characteristics of a proton halo extracted from different types of data have sometimes appeared contradictory. © 2004 American Institute of Physics