Leonard Siew


Consultant allergist


Leonard Siew is the lead consultant for the adult allergy immunotherapy service at Guy’s Hospital.

He graduated from Bristol University Medical School and read for a PhD in Immunology at King’s College London, investigating the effects of cigarette smoking on the inflammatory process in asthma, graduating without corrections. He then graduated with Merit with the MSc in Medical Leadership.

Leonard has over nine years clinical trials experience and worked on over 50 clinical trials. As a senior research physician at Quintiles Drug Research Unit at Guy’s Hospital, he was principal investigator for trials in asthma, COPD and challenge models of obstructive airways disease.

He trained and completed his allergy specialist qualification at Guy’s Hospital, London. He currently sits on the Joint Royal Colleges of Physicians Training Board specialist advisory committee in allergy as the curriculum and assessment lead.

Education and training

  • CCT in Allergy, General Medical Council, UK (2019)
  • MSc in Medical Leadership with Merit, Royal College of Physicians and Birkbeck, University of London, UK (2017)

  • PhD in Immunology, Pass with no corrections, King’s College London School of Medicine, UK (2015)

  • MRCP(UK), Royal College of Physicians of the United Kingdom (2005)

  • 2002 – Advanced Life Support Provider, Resuscitation Council (UK).

  • Recertified 2007, 2013 and 2018

  • MB ChB, Medical Degree, Medical School, University of Bristol, UK (1999)

Research interests

  • Immunotherapy and immunoregulation of Type I hypersensitivity reactions (immediate type allergy)
  • drug allergy

  • food allergy.

Last updated: April 2022

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