Although sensory nerve activity may be important to the human airway in numerous possible ways, the relevance of "neurogenic inflammation" to the onset and development of asthma is unknown. However, several of the symptoms of asthma (bronchoconstriction, cough, and dyspnea) have a neuronal component that can be modeled in the laboratory by various stimuli that are thought to invoke sensory nerve activation. Nedocromil sodium is highly effective against bronchoconstriction induced by bradykinin, the tachykinins substance P and neurokinin A, and sulfur dioxide and metabisulfite. The results for induced cough in healthy subjects are equivocal, although the drug is effective on spontaneously occurring cough in patients with asthma. Nedocromil sodium had a modest but significant effect on symptoms associated with episodes of viral infection.