About
Lt Col Zachariah Overby, MD is a board-certified Family Medicine physician serving members of Crossbridge Direct Primary Care in Greenville, SC. He earned his Doctorate of Medicine from the University of Tennessee Health Science Center in Memphis, Tennessee. He then completed his Family Medicine residency with the United States Air Force at Eglin Air Force Base. Both an Air Force veteran and a current Air Force Reservist, he holds an active role with the 315th Airlift Wing based out of Charleston, SC.
Dr. Overby pursued additional clinical training as an Air Force Allergy Extender through the Wilford Hall Medical Center Allergy/Immunology Training Program Short Course at Lackland Air Force Base. He holds ACLS and BLS certifications alongside his board certification in Family Medicine. He reaches patients beyond the office through house calls, workplace visits for business members, and text, voice, or video calls. Outside of medicine, he enjoys sports, the outdoors, a good cup of hot tea, and time with his wife and four children.
Education & Training
Medical School
University of Tennessee Health Science Center, Memphis, Tennessee
Residency
Family Medicine, Eglin Air Force Base (United States Air Force)
Additional Training
Air Force Allergy Extender Training, Wilford Hall Medical Center Allergy/Immunology Training Program Short Course, Lackland Air Force Base
Certifications
Who is Dr. Overby right for?
Dr. Overby serves patients across all age groups, from young children to older adults. Individuals managing chronic conditions benefit from his thorough, relationship-driven approach and long appointment times. Patients who need flexible scheduling, including early morning, evening, or Saturday visits, find his availability practical. Elderly patients in assisted living or skilled nursing facilities can receive house call visits. Businesses looking to offer primary care access to their employees also make strong use of his business membership model.
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Frequently Asked Questions
Dr. Overby handles a broad range of family medicine needs, from routine sick visits and annual exams to chronic disease management. His clinical scope also includes skin procedures, joint injections, vasectomies, testosterone testing and replacement therapy, EKGs, pulmonary function tests, and auricular acupuncture. He coordinates specialty referrals when care extends beyond primary medicine.
Yes. Dr. Overby holds board certification in Family Medicine. He also carries ACLS and BLS certifications. He trained at the University of Tennessee Health Science Center and completed his residency with the United States Air Force at Eglin Air Force Base.
Yes. Dr. Overby trained as an Air Force Allergy Extender through the Wilford Hall Medical Center Allergy/Immunology Training Program Short Course at Lackland Air Force Base. Through this training, he offers allergy testing and sublingual immunotherapy drops using the La Crosse Method Protocol at Crossbridge DPC.
Yes. Dr. Overby makes house calls when patients need them. He particularly values this option for elderly patients in skilled nursing facilities or assisted living care, where a home visit can also help assess fall risk in the living environment.
Yes. Dr. Overby communicates with patients by text, voice call, or video call. He also schedules in-person appointments before or after typical business hours and on Saturdays when needed.
Dr. Overby is both an Air Force veteran and a current Air Force Reservist. He serves with the 315th Airlift Wing out of Charleston, SC. He completed his Family Medicine residency with the United States Air Force at Eglin Air Force Base.
Yes. Dr. Overby provides care across all age groups, including children. For pediatric patients, the practice also partners with Dr. Rebecca Shoaf of BridgeWay Pediatrics, who works in the same office location.
Yes. Dr. Overby regularly visits the places of employment of Crossbridge DPC business members. He can meet with employees on-site, making primary care access more convenient for working adults.
Doctor profile last updated April 4, 2026