How can high altitude affect blood pressure?

Varies: Often unchanged, sometimes hypertension temporarily worsens for the 1st 1-2 weeks at altitude and then returns to normal. We guess this is related to stress hormones or unknown cause and more often in those with unstable pressure to begin with. In rare situations, it may drop. Stay on your medicine, cautious with salt,, & get seen if headache, chest pain, short of breath, or concerns beyond that.