["Acta Physiologica, Accepted Article. ", "\nAbstract\nDespite decades of research, the exact pathogenic mechanisms underlying acute mountain sickness (AMS) are still poorly understood. This fact frustrates the search for novel pharmacological prophylaxis for AMS. The prevailing view is that AMS results from an insufficient physiological response to hypoxia and that prophylaxis should aim at stimulating the response. Starting off from the opposite hypothesis that AMS may be caused by an initial excessive response to hypoxia we suggest that directly or indirectly blunting specific parts of the response might provide promising research alternatives. This reasoning is based on the observations that 1) humans, once acclimatized, can climb Mt Everest experiencing arterial partial oxygen pressures (PaO2) as low as 25 mmHg without AMS symptoms, 2) paradoxically AMS usually develops at much higher PaO2 levels, and 3) several biomarkers, suggesting initial activation of specific pathways at such PaO2, are correlated with AMS. Apart from looking for substances that stimulate certain hypoxia triggered effects, such as the ventilatory response to hypoxia, we suggest to also investigate pharmacological means aiming at blunting certain other specific hypoxia activated pathways, or stimulating their agonists, in the quest for better pharmacological prophylaxis for AMS.\nThis article is protected by copyright. All rights reserved.\n"]