Sales of Over-the-Counter Products Containing Codeine in 31 Countries, 2013-2019: A Retrospective Observational Study.

In many parts of the world, substantial numbers of people may be purchasing and consuming codeine in over-the-counter products. Clinicians should ask patients about their use of over-the-counter products, and public health measures are required to improve the collection of sales data and the safety of such products. STUDY PROTOCOL PRE-REGISTRATION: https://osf.io/ay4mc . The pre-print version of this work is available on medRxiv: https://doi.org/10.1101/2021.04.21.21255888 .