BACKGROUND AND AIMS: Clinicians could promote e-cigarettes for harm reduction to people who smoke but cannot stop, but many clinicians feel uneasy doing so. In a randomized controlled trial (RCT), primary care clinicians offered free e-cigarettes and encouraged people with chronic diseases who were unwilling to stop smoking to switch to vaping. We interviewed clinicians and patients to understand how to adopt harm reduction in routine practice.

DESIGN: Qualitative analysis nested within an RCT, comprising thematic analysis of semi-structured interviews with primary care clinicians who delivered the trial intervention, and patients who took part. Setting was primary care clinics in England. And involved twenty-one patients and 11 clinicians, purposively sampled from an RCT.

MEASUREMENTS: We qualitatively explored patients' and clinicians' experiences of: being offered/offering an e-cigarette, past and current perceptions about e-cigarettes and applying a harm reduction approach.

FINDINGS: Four themes captured clinicians' and patients' reported perspectives. These were: (1) concepts of safety/risk, with clinicians concerned about recommending a product with unknown long-term risks and patients preferring the known risks of cigarettes; (2) clinicians felt they were going out on a limb by offering these as though they were prescribing them, whereas patients did not share this view; (3) equating quitting with success, as both patients and clinicians conceptualized e-cigarettes as quitting aids; and (4) unchanged views, as clinicians reported that training did not change their existing views about e-cigarettes. These themes were united by the higher-order concept: 'The old and familiar meets the new and unknown', as a contradiction between this new approach and long-established methods underpinned these concerns.

CONCLUSIONS: A qualitative analysis found barriers obstructing clinicians and patients from easily accepting e-cigarettes for harm reduction, rather than as aids to support smoking cessation: clinicians had difficulty reconciling harm reduction with their existing ethical models of practice, even following targeted training, and patients saw e-cigarettes as quitting aids.