Absorbent articles for alerting a wearer to urination are disclosed. The absorbent articles comprise a bodyside liner, an absorbent core, and a urine-permeable inflatable envelope located between the bodyside liner and the absorbent core. The envelope comprises a surfactant and a system capable of generating a gas upon being wetted with urine. Upon urination, a foam is formed in the envelope such that the envelope inflates and causes the bodyside liner to press up against the skin of the wearer to alert the wearer to urination.