About
Justin Allen, DO, brings a background that few primary care physicians can match, combining internal medicine with subspecialty expertise in undersea and hyperbaric medicine. He received his doctorate in osteopathic medicine from Lake Erie College of Osteopathic Medicine and completed his internal medicine residency at Lakeland Health in Saint Joseph, Michigan. He then completed a fellowship in Undersea and Hyperbaric Medicine at Duke University Hospital, where he later served as an attending physician at the Duke Center for Hyperbaric Medicine and Environmental Physiology. In that role, Dr. Allen supervised inpatient and outpatient hyperbaric oxygen therapy, conducted commercial and recreational diving evaluations, and provided 24/7 emergency hyperbaric coverage across North Carolina, Virginia, and South Carolina. He also served as Assistant Professor of Medicine in the division of hospital medicine at Duke Raleigh Hospital. Dr. Allen holds additional expertise in VO2 max testing, pulmonary function, respiratory metabolism, performance nutrition, sleep optimization, and nutraceuticals. A lifelong endurance athlete, he competed with his wife Kaitlyn at the 2024 Half-Ironman World Championships and both earned USA Triathlon All-American status. He lives in Cary with his wife and daughter. Dr. Allen is currently accepting new patients at the Cary location.
Education & Training
Medical School
Lake Erie College of Osteopathic Medicine
Residency
Internal Medicine, Lakeland Health, Saint Joseph, Michigan
Fellowship
Undersea and Hyperbaric Medicine, Duke University Hospital
Additional Training
Assistant Professor of Medicine at Duke Raleigh Hospital; attending physician at Duke Center for Hyperbaric Medicine and Environmental Physiology
Certifications
Conditions Treated
Who is Dr. Allen right for?
Dr. Allen is an excellent fit for patients who want to optimize physical performance alongside conventional primary care. Athletes, active adults, and patients interested in VO2 max testing, sleep optimization, or metabolic performance will connect with his background. His hyperbaric medicine expertise also serves patients seeking regenerative or recovery-focused therapies. Dr. Allen currently accepts new patients at the Cary location.
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Frequently Asked Questions
Dr. Allen specializes in internal medicine and undersea and hyperbaric medicine. His additional clinical interests include performance nutrition, sleep optimization, nutraceuticals, VO2 max and pulmonary function testing, and metabolic performance. He brings both conventional internal medicine and elite athletic experience to patient care.
Yes. Dr. Allen holds double board certification in Internal Medicine and Undersea and Hyperbaric Medicine.
Dr. Allen earned his DO from Lake Erie College of Osteopathic Medicine and completed his internal medicine residency at Lakeland Health in Saint Joseph, Michigan. He then completed a fellowship in Undersea and Hyperbaric Medicine at Duke University Hospital and later served as an attending physician at the Duke Center for Hyperbaric Medicine and Environmental Physiology.
Dr. Allen supervised both inpatient and outpatient hyperbaric oxygen therapy treatments at Duke University Hospital. He also conducted commercial and recreational diving evaluations and provided 24/7 emergency hyperbaric coverage across North Carolina, Virginia, and South Carolina.
Yes. Dr. Allen has extensive experience evaluating physical fitness markers including VO2 max, pulmonary function, and respiratory metabolism. His personal background as a USA Triathlon All-American and Half-Ironman World Championship competitor informs his approach to helping patients reach elite physical performance.
Yes. Dr. Allen currently accepts new patients at the Essential Health Cary location.
Dr. Allen pairs internal medicine training with a full fellowship in Undersea and Hyperbaric Medicine, a rare combination in a primary care setting. His experience at Duke's hyperbaric center, combined with his personal history as a competitive endurance athlete, gives him a distinctive perspective on performance, recovery, and metabolic health.
Doctor profile last updated August 19, 2026