Nedocromil sodium has been shown to be capable of inhibiting chloride ion flux in mast cells, epithelial cells, and neurons. This feature may explain how it can prevent responses such as mast-cell degranulation, the effects of osmolarity changes in the airways, and neuronal activation. This mechanism may also provide a unifying hypothesis to explain the effects of nedocromil sodium on a range of cell types involved in asthma, such as sensory and efferent neurons and cells involved in inflammation.