Dr Lewis has over 27 years experience as a psychiatrist in public health psychiatric health teams in the UK, South Africa and Australia. He started his medical career working in trauma and acute settings in the South African townships during the periods of civil unrest. Dr Lewis spent 12 years as a frontline psychiatrist working in rural, acute and crisis teams and on psychiatric intensive care and forensic wards and has held positions of Director of Clinical Services in Canberra and Clinical Director in the U.K. national health service. Dr Lewis is currently the psychiatric lead in the crisis team at Canberra Hospital and has been awarded the UK National Royal College of Psychiatrists Adult Psychiatry Team of the year Award, 2014.

Dr Lewis moved to Australia and was appointed as Clinical Director for Community Mental Health at ACT Health and Canberra Health Services in 2017 where he led the implementation of a contemporary community mental health model of care, including establishing Assertive Community Outreach Services and the Home Assessment and Acute Response Team. He achieved his Fellowship of the Royal Australian and New Zealand College of Psychiatrists in 2018.  He served as Director of Clinical Services in the Mental Health Division of Canberra Hospital Services from 2020 until 2021 leading the development of the Coronavirus Pandemic Plan for the Division of Mental Health Justice Health ad Alcohol and Drug Services.
He is presently the Senior Specialist in the mental health crisis service in Canberra and is actively participating in registrar education and training and is the medical lead of a randomised controlled trial in physical and dietary interventions in patients on antipsychotics. Dr Lewis is an Honorary Clinical Fellow at the Australian National University and Principal Investigator in a randomised controlled trial of Psilocybin in treatment resistant depression with the Australian National University Medical School.
Dr Lewis is fascinated by novel therapies and has completed the Certificate in Psychedelic Therapies through Mind Medicine Institute and has a Professional Certificate in Medicinal Cannabis prescribing. In his private practice, Rainbow Mandala Clinic, he treats ADHD, commonly presenting mental disorders and has developed pathways for Ketamine Assisted Psychotherapy in collaboration with psychologists for chronic, difficult to treat psychiatric conditions.