Built to deliver what hospital systems can't
Synergy Rheumatology was designed around a premise: patients with complex autoimmune diseases deserve both cutting-edge medicine and a physician who actually knows them. We combined the diagnostic and treatment capabilities of a hospital rheumatology program with the continuity and access of a physician-owned practice.
The result: on-site infusions, same-day imaging, active research — and a team that knows your name when you call.
Zachary Fellows, MD
Board-Certified Rheumatologist
Dr. Fellows is a board-certified rheumatologist specializing in inflammatory arthritis, autoimmune disease, and musculoskeletal ultrasound. He serves on the Board of Directors of the California Rheumatology Alliance and maintains an active clinical research practice, serving as principal investigator for rheumatology trials.
He holds board certifications in Internal Medicine and Rheumatology through the American Board of Internal Medicine (ABIM), plus certification in Obesity Medicine from the American Board of Obesity Medicine. He achieved the RhMSUS (Rheumatology Musculoskeletal Ultrasound) qualification from the American College of Rheumatology, using ultrasound techniques to aid in diagnosis of musculoskeletal and inflammatory disorders and for precision-guided injections.
Dr. Fellows has a particular interest in fibromyalgia — a condition that often goes unrecognized or misunderstood — and regularly educates other physicians on recognizing and treating it effectively. He also maintains keen interest in interstitial lung disease intersecting with connective tissue diseases, emphasizing a multidisciplinary approach to care.
Education & Training
- Fellowship: University of Wisconsin–Madison Rheumatology
- Residency: Scripps Clinic/Green Hospital, Internal Medicine
- Medical School: Ross University School of Medicine
Dr. Fellows relocated to Carlsbad to be closer to family after practicing in Northern California's Bay Area. When not seeing patients, he spends time with his wife Sarah, two young children, and their dog Layla.
Board Certifications & Affiliations
How We Practice
Evidence-based medicine, practiced completely.
Evidence-based foundation
We are board-certified, allopathic physicians. When inflammatory disease demands medication — biologics, DMARDs, corticosteroids — we prescribe it without hesitation, backed by clinical evidence and active research participation. Rigorous medicine is the starting point, not the last resort.
Lifestyle as medicine
Sleep, diet, movement, and social connection aren't alternative medicine — they're clinical interventions with measurable effects on inflammation, pain, and disease activity. We recommend them for every patient as the base layer of treatment: not a substitute for medication, but the foundation that makes everything else work better.
Your choice, our support
We lay out your options, explain the trade-offs, and tell you what we'd recommend. Then you decide. This isn't "you have to take this" medicine — it's shared decision-making where you have the final word. Whatever path you choose, we monitor you through it and adjust the plan with you.
Your Dedicated Care Team
The same people, every visit — from your first call to every follow-up.
Glea S.
Patient Communications Coordinator
Off-site
Glea is the voice you hear when you call. She handles scheduling, referral coordination, and prior authorizations. Patients consistently tell us she's one of the friendliest, most helpful people they've ever worked with in a medical office.
Angela S.
Lead Medical Assistant
In-office
Angela manages day-to-day clinical operations and is the first face you'll see at your appointment. She coordinates your visit, takes vitals, and helps ensure everything runs smoothly from check-in to checkout.
Alex S.
Billing & Authorization Specialist
In-office
Alex handles insurance authorizations, prior approvals, and billing questions. If your medication needs a prior authorization or you have a billing concern, Alex is your point of contact.
Infusion Nursing Staff
Registered Nurses
In-office
Our registered nurses administer all biologic infusions in the on-site infusion center, monitoring you throughout your treatment to ensure safety and comfort.
Institutional capability, personal attention
Synergy Rheumatology offers the services you'd expect from a large health system — on-site biologic infusions, diagnostic ultrasound, clinical research — but in a physician-owned private practice where you're a person, not a patient number.
On-Site Infusion Center
RN-administered biologic infusions in a comfortable, monitored setting — no hospital visits or separate facilities.
Diagnostic Ultrasound
RhMSUS-certified musculoskeletal ultrasound with same-day imaging and results — no referral, no waiting weeks.
Clinical Research
Active clinical trials in rheumatology, physician-supervised on-site. Access to emerging therapies before they reach market.
Our Carlsbad Facility
Located in the Paseo Del Norte medical complex, our L-2 suite was designed specifically for comprehensive rheumatologic care.
Ready to get started?
Schedule an appointment or call for an introductory phone consultation to see if Synergy Rheumatology is the right fit.