To the Editor: Acetylcysteine (Mucomyst [Bristol-Myers Squibb, Melbourne]) is a mucolytic agent commonly used as adjuvant therapy for patients with abnormal, viscid or inspissated mucous secretions in such conditions as chronic bronchopulmonary disease. It is administered as fine nebulae, and its adverse effects in this form are minimal. Patients may observe an initial slight odour, or stickiness on the face after nebulisation.

When acetylcysteine is nebulised using a normal nebuliser it produces a dense mist. One of the less well known adverse effects of the medication was recently observed at a major teaching hospital, when an acetylcysteine cloud activated the hospital’s fire alarm!

Medical, nursing and pharmacy staff need to be aware of this potentially embarrassing situation. To help alleviate the problem, acetylcysteine can be administered via a jet nebuliser, similar to that used to administer the antimicrobial pentamidine. The jet nebuliser uses an air or gas stream to break liquids up into smaller particles, decreasing the droplet size and thus eliminating the dense mist.