Professor of Clinical Pediatrics and Medicine
Director, Division of Adolescent and Young Adult Medicine
  • Summary
  • Publications
  • Research
  • Media
  • Locations


Marvin Belzer, MD is an Adolescent Medicine physician who specializes in care for youth with HIV, transgender youth, and youth with chronic fatigue. He is a Professor of Clinical Pediatrics and Medicine who has been a USC faculty member for 24 years.

Dr. Belzer has provided care for youth at risk or living with HIV for 25 years and is a leading researcher on interventions to improve adherence to HIV medications. He is an internationally recognized leader in the field of transgender care for youth. In addition to providing information all over the world, Dr. Belzer has also appeared on MSNBC to educate audiences about the needs of transgender youth.


Clinical Interests

HIV; Gender Identity Disorder; Chronic Fatigue Syndrome; Medication Adherence


Medical School: 

University of Southern California Keck School of Medicine


University of California/Irvine Medical Center: Primary Care Internal Medicine


University of California/Irvine Medical Center: Primary Care Internal Medicine


Children's Hospital Los Angeles: Adolescent Medicine



Internal Medicine: American Board of Internal Medicine; Adolescent Medicine: American Board of Internal Medicine

Medical Memberships: 

Fellow, American College of Physicians, Fellow, Society for Adolescent Medicine, American Academy of HIV Medicine World Professional Association for transgender Health

Medical Awards: 

Barbara Korsch Award for Medical Education


Belzer ME, Naar-King S, Olson J, Sarr M, Thornton S, Kahana SY, Gaur A, Clark L. The Use of Cell Phone Support for Non-Adherent HIV-Infected Youth and Young Adults: An Initial Randomized and Controlled Intervention Trial. AIDS and Behav (2013) DOI 10.1007/s10461-012-0661-3

Simons L*, Schrager SM, Clark LF, Belzer M, Olson J. Parental Support and Mental Health Among Transgender Adolescents. Journal of Adolesc Health. 2013:53:791 – 793.

Nadia Dowshen, MD1,2*, Meredith Matone, MHS1, Xianqun Luan, PhD1, Susan Lee1, Marvin Belzer, MD3, Maria Isabel Fernandez, PhD4, David Rubin, MD, MSCE1,2 and the Adolescent Medicine Trials Network for HIV/AIDS Interventions. Behavioral and Health Outcomes for HIV+ Young Transgender Women (YTW) Linked to and Engaged in Medical Care. LGBT Health. 2015 DOI: 10.1089/gbl.2014.0062

Marvin E Belzer, Karen Kolmodin-MacDonell, Leslie F Clark, Jennifer Huang, Johanna Olson, Shoshana Y Kahana, Sylvie Naar-King, Moussa Sarr, Sarah Thornton. Acceptability and Feasibility of a Cell Phone Support Intervention for Youth Living with HIV with Nonadherence to Antiretroviral Therapy. AIDS Patient Care and STDs.2015;19:338—345. DOI: 10.1089/apc.2014.0282

Olson J, Schrager S, Belzer M, Simons L, Clark L. Baseline Physiologic and Psychosocial Characteristics of Transgender Youth Seeking Care for Gender Dysphoria. Journal of Adolescent Health, July 2015 DOI: 10.1016/j.jadohealth.2015.04.027

Research Interests: 


Research Topics

  • HIV in Adolescents

  • HIV Medication Adherence

  • Gender Identity and Transgender Care for Youth

Research Overview

Youth with HIV have been frequently shown to have poor adherence to their medications. This can lead to poor health, development of HIV strains resistant to medications and transmission of HIV to sexual partners. My team is developing innovative strategies to try to improve medication adherence for youth by incorporating the use of cell phones to provide needed support.

My secondary research interest involves mentoring Johanna Olson, MD in her quest to research the impact of healthcare for transgender youth, including hormone blocking medication during puberty and cross gender hormones later in adolescence.

HIV Adherence Research 

Dr. Belzer’s team has worked as part of the NICHD’s Adolescent Trials Network (ATN) for the past 11 years. In addition to participating in numerous clinic trials for youth infected with HIV, Dr. Belzer has been on key protocol teams focusing on nonadherence. One protocol used 4 sessions of motivational interviewing to improve medication nonadherence. A second protocol recently completed used web based motivational support for youth advised to start HIV medication and found improved initiation and adherence 3-6 months out. Dr. Belzer recently completed a pilot study utilizing cell phone support in youth nonadherent to antiretroviral medications and preliminary findings indicate statistically and clinically improved adherence and improved HIV RNA (viral loads) at 24 and 48 weeks. This is the first controlled study to demonstrate maintained improvements in adherence, 24 weeks past the completion of the intervention.

Transgender Research

Dr. Belzer and Johanna Olson, MD look to define the treatment for children and youth with gender nonconformity inThe Center for Transyouth Health and Development at Children's Hospital Los Angeles. She was awarded a KL-2 award for the USC CTSI in July of 2012 to study to impact of Gonadotropin Releasing Hormone agonists (puberty blockers) with peripubertal transgender youth and look at physiological impact, psychological impact and quality of life. We also are currently following longitudinally a cohort of 81 (and growing) transgender youth new to cross gender hormones. This is by the far the largest cohort in the United States and should demonstrate the safety of currently recommended treatments (previously reported in a score of youth from the Netherlands) and also demonstrate any impact on quality of life and risk behaviors like suicide attempts, high risk sex, and substance abuse. Baseline analyses indicate this cohort has high levels of obesity, depression and previous suicidality and that parental support is associated with reduced risk.

Key Findings

  • Demonstrated that provision of an advanced supply of emergency contraception to parenting teens markedly increased utilization for unprotected sex and is now the standard of care.

  • Published the first manuscript in 1999 demonstrating the prevalence of nonadherence in youth living with HIV.

  • Through a small pilote study, we demonstrated that providing cell phone reminders to youth improved adherence to HIV medications during the intervention, but were not maintained.

  • Launched the first controlled trial to provide support to HIV youth through short daily cell phone conversations. Through the 24 week intervention and 24 week post-intervention,  adherence significantly improved the HIV RNA level of impact. Future analyses should be able to determine critical information on how improvements were mediated.


  • National Institute of Health (NIH) Adolescent Trials Network
  • Westat
  • University of Alabama Birmingham
  • University of Southern California  


  • NICHD Adolescent Medicine Trials Network for HIV-AIDS Interventions
  • NICHD International Maternal Pediatric Adolescent AIDS Clinical Trials
  • NICHD Support for Dr. Belzer to Chair the Clinic PI’s in the ATN Network

5000 Sunset Blvd.
Suite 400
Los Angeles, CA 90027-6062
Phone: 323- 361-2153Office
Fax: 323-953-8116Fax