Offering an overview of the medical discovery that peptic ulcers are primarily caused by the bacterium Helicobacter pylori, rather than just stress or excess stomach acid, which was the prevailing medical dogma for decades. Centering on the efforts of Australian researchers Dr. Barry Marshall and Dr. Robin Warren, who made this controversial finding in the early 1980s. To prove their hypothesis, Dr. Marshall famously ingested the bacteria himself, developing gastritis and ulcers, which he then cured with antibiotics. Despite initial skepticism and ridicule from the medical establishment, the link between H. pylori and ulcers, and the effectiveness of antibiotic treatment, gained acceptance by the mid-1990s and is now standard therapy, leading to Marshall and Warren being awarded the Nobel Prize in 2005. The sources also highlight the irony that earlier researchers had observed similar bacteria but were blinded by the acid theory, significantly delaying the development of an effective cure.