I have ulcers of the base of the oesophagus and a hiatal hernia. Diagnosed a year ago by endoscopy.( 4 ulcers, 2 bleeding spontaneously, but no bacteria.) I take Nexium daily and have never felt pain, but have occasional discomfort, and have been treated for iron deficiency. I am contemplating a trekking holiday at middle altitudes, 1000m to 2800m, and would like to know if this increases the risk of bleeding ulcers. Thank you.