['Nasal polyposis associated with aspirin-intolerant asthma tends to be difficult to control, with frequent recurrences. We examined the effect of intranasal lysine-aspirin administration on resistant nasal polyps of asthmatic, aspirin-intolerant patients, when used in addition to routine therapy.', 'Thirteen patients with asthma and intolerance to aspirin were recruited. All but one had undergone numerous polypectomies and were uncontrolled on standard therapy with intranasal corticosteroids, leukotriene receptor antagonists and nasal douching. Aspirin treatment involved one drop (100 microl) of 30 mg/ml lysine-aspirin solution to each nostril, initially daily, increased every two or three days up to a maximal of 18 drops (54 mg lysine-aspirin) a day. Nasal symptoms, nitric oxide level, nasal inspiratory peak flow rate, peak expiratory flow rate and nasendoscopic grading were assessed prior to therapy and three months later. We also compared the change in endoscopic polyp scores during three months of lysine-aspirin administration with the changes which had occurred during the three months prior to administration (during which time other therapies had been identical).', 'Nasal blockage symptoms tended to decrease; other nasal symptoms were unchanged. Significant changes were seen in nasal inspiratory peak flow rate (103.3 +/- 18.9 and 140.0 +/- 16.7 l/min before and after aspirin, respectively; p = 0.014), but not in peak expiratory flow rate (438.7 +/- 33.4 and 440.0 +/- 28.4 l/min before and after aspirin, respectively; p = 0.700). Nasal nitric oxide levels rose significantly (in both sides, p = 0.028). Expired chest nitric oxide levels did not change. Nasal polyp scores on nasendoscopic examination were significantly reduced (right side, p = 0.027; left side, p = 0.018). Compared with the preceding three months, adding intranasal lysine-aspirin application had the effect on decreasing nasal polyp volume (right side, p = 0.031; left side, p = 0.016).'] Does intranasal lysine-aspirin administration decrease polyp volume in patients with aspirin-intolerant asthma?