Dr Fahy graduated from University College Galway in 1988 and received his MRPCI certification in 1991.

He completed a residency at UNMC, Omaha becoming board certified in Internal Medicine, Pulmonary Medicine and Critical Care Medicine.

He completed a fellowship in Pulmonary and Critical Care Medicine at The Ohio State University in Columbus and joined staff as an assistant professor of Pulmonary and Critical Care Medicine with NIH funding research into acute lung injury and fibrosis. He was conferred a fellow of the American College of Physicians in 2001.

He returned to St James's Hospital in 2006 and was conferred a fellow of the Royal College of Physicians of Ireland in 2008.

Dr Fahy has a special interest in sarcoidosis, rheumatologic, immunologic, fibrotic lung diseases and lung complications of bone marrow transplantation.

He is involved in international multi-centred studies with novel therapeutic antifibrotic agents at the Wellcome Trust HRB Clinical Research Facility at St James's Hospital.

Dr Fahy is a member of the American Thoracic Society, Irish Thoracic Society and the American College of Chest Physicians.