Cynthia Castillo, MD

Meet Cynthia Castillo, MD

Expert Internal Medicine Clinician & Academic Leader in San Antonio 

Dr. Cynthia Castillo is a board-certified internal medicine clinician at CHRISTUS Trinity Clinic, where she combines high-level diagnostic expertise with a deep-rooted commitment to the San Antonio community. A graduate of the UT Health San Antonio Long School of Medicine, Dr. Castillo has spent over a decade practicing in the same city where she completed her residency, fostering long-term relationships with patients across South Texas. Beyond her clinical practice, she has served as an Assistant Professor of Medicine, shaping the next generation of healthcare providers through her work with the UT Health Science Center. Her path from studying nuclear engineering at MIT to becoming a primary care provider shapes her analytical and detail‑oriented approach to complex chronic care. She uses that expertise to help patients clearly understand their health and feel confident in managing long‑term conditions. 

Career at a Glance 

• 15+ Years of Medical Excellence: Dedicated to serving the San Antonio and Bexar County community. 

• MIT-Trained Analytical Approach: Holds a B.S. in Nuclear Engineering from the Massachusetts Institute of Technology, bringing a high level of precision to internal medicine. 

• Bilingual Provider: Fully fluent in English and Spanish, ensuring accessible care for the diverse South Texas community. 

• Academic Preceptor: Actively mentors residents and nurse practitioners in advanced clinical evaluation and primary care. 

Clinical Role and Leadership 

Dr. Castillo focuses on bridging the gap between academic research and bedside care. She provides comprehensive management for adult patients, with a specific emphasis on preventative screenings and the stabilization of chronic illnesses. She treats a wide range of conditions, including: 

• Diabetes management 

• Hypertension and cardiovascular risk 

• Care for coughs, colds, skin irritations, and other acute concerns  

• Preventative health and routine screenings 

What You Can Expect from Care with Dr. Castillo 

Dr. Castillo’s philosophy is built on the "big picture" of health. She knows patients get the best results when expert treatment is paired with trust, open communication, and true partnership. She’s known for asking thoughtful, guiding questions that help patients express what they’re feeling, making sure no detail is missed. When you visit her, you can expect 

• Collaborative Decision-Making: She actively seeks your opinion and consent when finalizing treatment plans. 

• Comprehensive Patient Education: Complex diagnoses are explained in simple, practical steps to give you clear ‘at‑home’ guidance to support your recovery.

• Communication Fluency: Professional, fluent care in Spanish for native speakers. 

• Attentive Listening: A bedside manner that prioritizes time and respect, ensuring you never feel rushed through an appointment. 

Research, Clinical Insight, and Thought Leadership 

Dr. Castillo is a contributor to the global medical community through her focus on implementation science. Her work evaluates how healthcare systems can better adopt new technologies and treatments in real-world settings. By serving as a preceptor for the Advanced Clinical Evaluation Skills (ACES) program, she ensures that the latest clinical guidelines are integrated into the daily practice of emerging healthcare professionals. 

Commitment to Public Health and Health Equity 

Driven by a mission to reduce healthcare disparities, Dr. Castillo focuses heavily on health equity within Latino communities. Her bilingual outreach and participation in community health initiatives ensure that high-quality internal medicine is reachable for all residents, regardless of socioeconomic background while continuing to advocate for rural and minority health access.