Mostafa Mahmoud, a hotel worker from Edinburgh, developed the ulcer when he was only about 3,000 feet from the summit of the 29,028-foot peak in Nepal, reports the Scotsman.
The Everest attempt was part of Mahmoud's plans to climb the highest mountains in each of the world's seven continents by early 2006.
But the plan failed after the expedition leader ordered him back down the mountain just two days before the rest of the team reached the summit.
The 34-year-old, originally from Jordan, spent years training for the task including scaling other mountains in Nepal and Tibet. Earlier this year, Mahmoud completed a 17-day trek to the summit of Vinson Massif, the highest mountain in Antarctica.
Mahmoud began his Everest climb April 1, accompanied by 11 climbers and six guides.