John Fahy, MSc, MD


Dr. John Fahy is a pulmonologist at UCSF Medical Center who has a special interest in treating patients with asthma. Fahy directs the severe asthma clinic at UCSF. He also cares for critically ill patients in the medical center's intensive care units.

As a researcher, he directs the UCSF Airway Clinical Research Center. At the center he receives funding from the National Institutes of Health and foundations, as well as contracts from biotechnology and pharmaceutical companies to conduct clinical research in asthma, cystic fibrosis and other airway diseases to uncover underlying disease mechanisms.

Fahy earned a medical degree at University College Dublin in Ireland in 1985. After internal medicine training in Dublin, he completed pulmonary and critical care fellowship training at UCSF and joined the faculty in 1993 in the Pulmonary and Critical Care Division. He is a professor in residence in the UCSF School of Medicine, where he holds the Michael S. Stulbarg Endowed Chair in Pulmonary Medicine.


Asthma Clinic
400 Parnassus Ave., Fifth Floor
San Francisco, CA 94143-0359
Phone: (415) 353-2961

Hours: Thursdays
8:30 – 11:30 a.m.

Pulmonary Practice at Parnassus
400 Parnassus Ave., Fifth Floor
San Francisco, CA 94143-0359
Phone: (415) 353-2961
Fax: (415) 353-2568

Hours: Monday to Friday
8 a.m. – 5 p.m.

Conditions & Treatments

  • Severe Asthma

Board Certification

Internal Medicine, American Board of Internal Medicine

Academic Title


More about John Fahy


University College, Dublin Ireland 1985


University College Dublin, Internal Medicine 1989


UCSF, Pulmonary Medicine 1992

Selected Research and Publications

  1. Ash SY, Rahaghi FN, Come CE, Ross JC, Colon AG, Cardet-Guisasola JC, Dunican EM, Bleecker ER, Castro M, Fahy JV, Fain SB, Gaston BM, Hoffman EA, Jarjour NN, Mauger DT, Wenzel SE, Levy BD, San Jose Estepar R, Israel E, Washko GR. Pruning of the Pulmonary Vasculature in Asthma: The SARP Cohort. Am J Respir Crit Care Med. 2018 Apr 19.
  2. DeBoer MD, Phillips BR, Mauger DT, Zein J, Erzurum SC, Fitzpatrick AM, Gaston BM, Myers R, Ross KR, Chmiel J, Lee MJ, Fahy JV, Peters M, Ly NP, Wenzel SE, Fajt ML, Holguin F, Moore WC, Peters SP, Meyers D, Bleecker ER, Castro M, Coverstone AM, Bacharier LB, Jarjour NN, Sorkness RL, Ramratnam S, Irani AM, Israel E, Levy B, Phipatanakul W, Gaffin JM, Gerald Teague W. Effects of endogenous sex hormones on lung function and symptom control in adolescents with asthma. BMC Pulm Med. 2018 Apr 10; 18(1):58.
  3. Ricklefs I, Barkas I, Duvall MG, Cernadas M, Grossman NL, Israel E, Bleecker ER, Castro M, Erzurum SC, Fahy JV, Gaston BM, Denlinger LC, Mauger DT, Wenzel SE, Comhair SA, Coverstone AM, Fajt ML, Hastie AT, Johansson MW, Peters MC, Phillips BR, Levy BD. ALX receptor ligands define a biochemical endotype for severe asthma. JCI Insight. 2018 Mar 22; 3(6).

Publications are derived from MEDLINE/PubMed and provided by UCSF Profiles, a service of the Clinical & Translational Science Institute (CTSI) at UCSF. Researchers can make corrections and additions to their publications by logging on to UCSF Profiles.