Drug prevention of acute mountain sickness and high-altitude cerebral oedema
There is no substitute for a sensible rate of ascent in preventing acute mountain sickness and high-altitude cerebral oedema. However, if moderate- to high-risk situations are unavoidable, prophylactic acetazolamide can be considered for prevention of acute mountain sickness (AMS) and high-altitude cerebral oedema (HACE)1.
Acetazolamide stimulates physiological processes (eg diuresis) that occur in normal acclimatisation, reducing the duration of symptoms such as headache.
For prevention of acute mountain sickness and high-altitude cerebral oedema, use:
acetazolamide 125 mg (child: 2.5 mg/kg up to 125 mg) orally, 12-hourly, starting the day before ascent. Continue for 2 days once at final altitude (or until final descent is started if this occurs sooner)Luks, 2019. acetazolamide acetazolamide acetazolamide
Allergy to a sulfonamide antibiotic may be associated with a slight increase in the risk of acetazolamide allergy. The basis of this association is not fully understoodShah, 2018. Acetazolamide is contraindicated if a person has a history of anaphylaxis or a severe cutaneous adverse reaction (such as drug rash with eosinophilia and systemic symptoms [DRESS] or Stevens–Johnson syndrome / toxic epidermal necrolysis [SJS/TEN]) with sulfonamide useLuks, 2019. If the history of a sulfonamide reaction is less certain, refer the person to a specialist for allergy testing or consider a supervised trial of acetazolamide before the trip (the person should take the first dose in a setting with resuscitation facilities). A supervised trial of acetazolamide at sea level is also useful to determine how well a person tolerates its expected effects, particularly if they will be doing complex tasks at altitude. Among the most troublesome effects are perioral and digital paraesthesia; other expected effects include anorexia, polyuria, polydipsia, tinnitus and headacheKayser, 2012.
Dexamethasone can have more severe adverse effects than acetazolamide, and should ideally only be used short term. Evidence for its use in altitude illness prevention is weak. It is used for prophylaxis of acute mountain sickness and high-altitude cerebral oedema in those who are allergic to or intolerant of acetazolamide2.
If dexamethasone is considered appropriate for prevention of acute mountain sickness and high-altitude cerebral oedema, in adults use:
1dexamethasone 2 mg orally, 6-hourly, starting the day before ascent. Continue dexamethasone for 2 days after reaching final altitude (or until starting final descent if this occurs sooner). Do not use for more than 10 days in total dexamethasone dexamethasone dexamethasone
OR
1dexamethasone 4 mg orally, 12-hourly, starting the day before ascent. Continue dexamethasone for 2 days after reaching final altitude (or until starting final descent if this occurs sooner). Do not use for more than 10 days in totalLuks, 2019. dexamethasone dexamethasone dexamethasone
Dexamethasone is not recommended as prophylaxis in children.
Ibuprofen can prevent acute mountain sickness and high-altitude headache (mild to moderate headache without other features of acute mountain sickness) but does not have a known role in prevention of high-altitude cerebral oedemaGertsch, 2010. It can be considered for short-term use for those who are allergic to or intolerant of acetazolamide or dexamethasone. It should not be used for more than 48 hours as it may cause sodium and water retention.
For short-term prevention of acute mountain sickness (or high-altitude headache) in adults who are not able to take acetazolamide or dexamethasone, consider:
ibuprofen 600 mg orally, 8-hourly, starting 24 hours before ascent. Do not continue use beyond 48 hoursGertsch, 2010 Luks, 2019. ibuprofen ibuprofen ibuprofen