Coghlan was the grandson of an English doctor who settled in Chile. He earned his bachelor's degree at the Universidad Católica de Chile in 1950 and his medical degree from the Universidad de Chile in 1956. While serving as chief resident at the hospital in the copper mining city of Sewell, Coghlan served as translator for visiting cardiologist Tinsley Harrison. Harrison invoted Coghlan to come to Birmingham as a visiting researcher and clinical fellow at the University of Alabama School of Medicine.
Coghlan spent three years at the School of Medicine, then returned to Universidad de Chile's medical school to continue his research and clinical work and begin his career as an educator. Coghlan returned to UAB as a visiting professor in 1973 and was promoted to full professor in 1981.
Coghlan's research centered on mitral valve prolapse, autonomic dysfunction, and dysautonomia. He invented a tilt test for heart disorders and pioneered its use at UAB. In addition to his research and teaching, he has participated in numerous visits with disadvantaged communities in South and Central America as well as Alabama to treat patients and instruct caregivers. He was appointed director of the Uihlein Autonomic Research Laboratory and deputy director of the UAB Division of Cardiology. An annual award for teaching excellence in the Division of Cardiovascular Disease is named in his honor.
In 2002 Coghlan heard a presentation by amateur researcher Doug Lindsay at the American Autonomic Society's annual conference at Hilton Head, South Carolina and agreed to work with him to treat Lindsay's undiagnosed condition with a noradrenaline drip, and eventually to isolate a diagnosis, bilateral adrenal medullary hyperplasia, and to arrange for an unproven surgical procedure to remove his adrenal medullas. The procedure was successful.
- Mora, Vivian (December 2008) "A Chilean Cardiologist with a Heart Bigger than Life." Birmingham magazine. Vol. 48, No. 12, p. 268
- Carter, Kendra (December 29, 2014) "Retired longtime professor Cecil Coghlan passes away" UAB News
- Eagle, Leah Ingram (January 17, 2015) "Dr. Cecil Coghlan made many contributions to the UAB Department of Cardiology." The Birmingham News
- Prior, Ryan (July 27, 2019) "This college dropout was bedridden for 11 years. Then he invented a surgery and cured himself" CNN