An altitude sickness pill shows promise against sleep apnoea

Sleep-disordered breathing, which covers both obstructive and central sleep apnoea, affects millions of adults worldwide and is associated with significant cardiovascular morbidity. The standard treatment, continuous positive airway pressure, works well for many people but has real limitations in certain groups, particularly those with central or complex forms of apnoea. That gap has driven interest in drug treatments, and acetazolamide, a carbonic anhydrase inhibitor best known for preventing altitude sickness, has an emerging mechanistic rationale: inhibiting carbonic anhydrase appears to stabilise the body's control of breathing during sleep.

The reviewers searched PubMed, Scopus, Web of Science and the Cochrane Library, turning up 462 records. After removing duplicates and screening, 17 randomised controlled trials met the inclusion criteria. Study quality was judged with the Cochrane Risk of Bias 2.0 tool. Because the trials differed substantially in populations, settings and outcomes, results could not be combined into a single pooled estimate, so the team synthesised the findings narratively, comparing what acetazolamide did across distinct contexts: obstructive apnoea at low altitude, central apnoea associated with heart failure, and healthy adults sleeping at altitude.

Acetazolamide generally improved night-time oxygen levels and reduced the burden of breathing events, but the size of the effect depended heavily on context. In obstructive sleep apnoea at low altitude, reported reductions in the apnoea-hypopnoea index ranged from roughly 42 to 69.4%. In central sleep apnoea linked to heart failure, the central apnoea index fell by approximately 53%. In healthy adults exposed to altitude, the drug cut the apnoea-hypopnoea index by around 11 events per hour and the oxygen desaturation index by 15 events per hour, with nocturnal oxygenation rising by 2 to 5%. No uniform treatment effect emerged.

The review supports a context-dependent and phenotype-dependent role for acetazolamide rather than a one-size-fits-all therapy, which fits the growing picture of sleep apnoea as a condition with several distinct underlying mechanisms. It strengthens the case that stabilising ventilatory control can help, particularly for central apnoea, altitude-related breathing instability, and people with obstructive apnoea seeking alternatives to CPAP. What it cannot yet say is who responds, at what dose, and for how long: the authors call for large, long-term trials to settle dosing and identify responder profiles.

If you have sleep apnoea and struggle with CPAP, the useful message is that pharmacological options are being tested seriously, and this one shows genuinely encouraging signals across randomised trials. The same drug already familiar to mountaineers also improved night-time breathing in healthy people sleeping at altitude, which is interesting context for anyone who treks or holidays high up. None of this amounts to something you can act on yourself: acetazolamide is a prescription medicine, the benefits varied widely by type of apnoea, and bigger trials are still needed.