Why go back?: Advantages and challenges of longitudinal qualitative research in social pharmacy, and recommendations for social pharmacy researchers.

Objectives: Although most qualitative research is cross-sectional, particularly in social pharmacy/pharmacy practice, there are many advantages of using a longitudinal qualitative research (LQR) design, i.e. re-interviewing participants over a period of time.

Methods: This paper describes some advantages and challenges of LQR using our 'Access to Medicines: Exploring Lived Experience to inform policy and programmes' study as an illustration.

Key findings: Advantages of LQR include obtaining richer and more complete data, providing a greater understanding of change and lack of change, understanding pathways through complex systems, including people facing difficult social circumstances, and contributing to evaluation research. Challenges to be addressed include the implications of developing friendships with participants, deciding whether to assist participants, maintaining participant anonymity, the impact of the research on the researchers, and how to analyse the large volume of data generated.

Conclusions: We recommend piloting methods before starting a study, considering the resource implications of LQR, planning the analysis in advance, planning for how to deal with developing friendships with participants, considering threats to participant anonymity, and supporting researchers doing fieldwork.