John Lykoudis (Greek: Ιωάννης Λυκούδης; 1910 in Missolonghi – 1980) was a doctor in Greece who treated patients suffering from peptic ulcer disease with antibiotics long before it was commonly recognized that bacteria were a dominant cause for the disease.
After treating himself for peptic ulcer disease with antibiotics in 1958 and finding the treatment effective, Lykoudis began treating patients with antibiotics. After experimenting with several combinations of antibiotics he eventually arrived at a combination which he termed Elgaco and which he patented in 1961. It has been estimated that he treated more than 30,000 patients.
In his time he had great difficulties in persuading the Greek medical establishment about the effectiveness of the treatment. He was given a fine of 4000 drachmas by a disciplinary committee, and indicted in the Greek courts. He was unable to get an article published in the Journal of the American Medical Association and was not able to get the established pharmaceutical companies sufficiently interested in the treatment.
John Lykoudis was the mayor of Missolonghi between 1952 and 1960.
- Basil Rigas, Efstathios D. Papavasassiliou, "John Lykoudis. The general practitioner in Greece who in 1958 discovered the etiology of, and a treatment for, peptic ulcer disease", in Barry Marshall (editor), Helicobacter Pioneers. Firsthand accounts from the scientists who discovered helicobacters, 1892-1982, 2002, ISBN 0-86793-035-7.