Twelve neurologically normal young adults were tested before and after administration of meclizine, an over-the-counter medication for motion sickness. The battery consisted of four components: (1) repeated-measures distortion-product otoacoustic emissions (DPOAEs); (2) the repeated-evoked-potentials version of the auditory brain-stem response (REPs/ABR); (3) quantitative electroencephalography (qEEG) measured over left- and right-side auditory cortex; and (4) a computer-based eye--hand coordination task. The battery required approximately 1.5 h to complete. Each subject was tested with the battery in each of eight longitudinal sessions: three times on a control day (no medication); the same times on a second day one week later (medication at mid-day); and 24- and 48-h check-up sessions following the medication day. Results show dramatic changes in all battery components, with details suggesting the site(s) of action of this type of antihistamine. The ``auditory-system cross sections'' yielded by this battery make it possible to observe effects from periphery to cortex, including evidence linking otoacoustic emissions with central auditory physiology. Implications range from cautions regarding the acute effects of antihistamines, to physiological support for using such medications to improve performance in learning-disabled children.