If a supplement works, then it is changing something in the body and you are taking a medicine without the quality checks that go into pharmaceuticals. The idea that a supplement is somehow better than a pharmaceutical in general is a false premise. If it is just about convenience of OTC vs Rx then consider the following from the WMS:
https://journals.sagepub.com/doi/full/10.1016/j.wem.2019.04.006
Not great evidence, but better than anecdote. As with everything else, there are also real risks with it, but at least you can know what they are, unlike with supplements.
Ibuprofen
Two trials demonstrated that ibuprofen (600 mg 3 times daily) is more effective than placebo at preventing AMS,
42,
43 while a third, smaller study showed no benefit.
44 Another study claimed to show benefit, but the trial did not include a placebo arm and instead compared the incidence of AMS with ibuprofen with historically reported rates from the region in which the study was conducted.
45 Although no studies have compared ibuprofen with dexamethasone, 2 studies have compared ibuprofen with acetazolamide. The first found an equal incidence of high altitude headache and AMS in the acetazolamide and ibuprofen groups, with both showing significant protection compared to placebo.
46 A more recent trial failed to show that ibuprofen was noninferior to acetazolamide (ie, ibuprofen is inferior to acetazolamide for AMS prophylaxis).
47 The aforementioned trials all used the medication for a short duration (∼24 to 48 h). As a result, efficacy and safety (eg, the risk of gastrointestinal bleeding or renal dysfunction) over longer periods of use at high altitude remain unclear. For these reasons, as well as more extensive clinical experience with acetazolamide and dexamethasone, ibuprofen cannot be recommended over these medications for AMS prevention for rapid ascent.
Recommendation. Ibuprofen can be used for AMS prevention in persons who do not wish to take acetazolamide or dexamethasone or have allergies or intolerance to these medications. Recommendation Grade: 2B.