Wheezing

Wheezing is the high-pitched whistling sound of air moving through narrowed airways, usually loudest on breathing out. In adults and children the commonest causes are asthma and allergic airway inflammation, viral infections including bronchiolitis in infants, and COPD in older adults with a smoking history. Less obvious causes matter too: heart failure can produce wheeze through pulmonary congestion, gastro-oesophageal reflux and post-nasal drip trigger it, vocal cord dysfunction mimics it, and in a child with sudden wheeze and no infection an inhaled foreign body must be considered. The single most important point is that wheezing is a sign of airway narrowing, not a diagnosis, and treatment depends entirely on what is causing it - which is why prescribed inhalers, and preventer inhalers in particular, should never be reduced or replaced on the basis of a supplement. Where supplements have any role it is peripheral and modest. Vitamin D supplementation has reduced asthma exacerbation rates in meta-analysis, most clearly in people who were deficient. Omega-3 fats, magnesium and vitamin C have small or inconsistent trial results for asthma symptoms; intravenous magnesium is used in acute severe asthma in hospital, which is a different thing from oral supplementation. Identifying and reducing triggers does more than any of them.