For decades, people with stomach ulcers were told to adjust their diet and take antacids (IIRC). I know someone who suffered for 25 years before it was recognized that stomach ulcers were caused by H. pylori. Back then I listened to Dr. Gabe Merkin on the radio and he was prescribing antibiotics for stomach ulcers when sufferers came to him as a last resort. They usually got cured. Meanwhile, the medical industry had patients for life insisting that there was no cure.
Read about Barry Marshall :
Australian physician, Nobel Laureate in Physiology or Medicine, Professor of Clinical Microbiology and Co-Director of the Marshall Centre at the University of Western Australia. Marshall and Robin Warren showed that the bacterium Helicobacter pylori (H. pylori) plays a major role in causing many peptic ulcers, challenging decades of medical doctrine holding that ulcers were caused primarily by stress, spicy foods, and too much acid. This discovery has allowed for a breakthrough in understanding a causative link between Helicobacter pylori infection and stomach cancer.
After Robin Warren discovered colonies of bacteria at gastric ulcer sites, he was contacted by his colleague Barry Marshall, who then successfully cultivated the previously unknown bacteria Helicobacter pylori. Warren and Marshall proved in 1982 that patients could only be cured if the bacteria were eliminated. This is now achieved by treatment with antibiotics, and gastric ulcers are no longer a chronic illness.