Dr. Sim has been in private practice in the Clear Lake/Friendswood/Galveston area for 20 plus years, specializing in adult and pediatric allergy, asthma and clinic immunology. He has completed residency training in both Internal Medicine and Pediatrics. Dr. Sim is certified by the American Board of Allergy and Immunology and has been a member of the Clinical Faculty, Adult and Pediatric for over 20 years with UTMB. He also served as Chief of Allergy Clinical Service, UTMB Galveston. He also uses his practice as part of clinical rotations for UTMB Allergy Postdoctoral Fellows.

Dr. Sim resides in the Clear Lake area with his wife and has three grown children. He enjoys time with his family and stamp collecting, especially stamps from the Philippines where he grew up.