An email about changes to the interactions section in the BNF has worried Vicki, the pharmacy technician...

“This email alert says that the BNF has changed the way it provides information about interactions – do you know anything about it, Parveen? I feel like I’ve only just got my head around the way they do the product monographs, so I’m really hoping it isn’t anything like that.”


The interactions sections of both the BNF and BNF for Children (BNFC) have been updated to incorporate the following changes:

  • Interaction severity is stated as mild, moderate, severe or unknown, to help clinicians distinguish between clashes that are dangerous and those that are likely to cause relatively minor issues for the patient.
  • The evidence level for each interaction is given, so users can tell which is known about from formal research studies, those that have become known because of anecdotal reports, and any that are predicted based on theoretical considerations. It is worth noting that this last group may be based on the way other agents in the same drug class interact, as well as from in vitro studies.
  • Information is now provided on the recommended actions that should be taken as a result of a patient being considered for two medicines that interact (e.g. whether a manufacturer advises avoiding the second drug altogether or adjusting the dose).
  • While drug interactions are still contained in Appendix 1 of both publications, this section also now includes relevant “notes” that previously appeared only in drug monographs or clear signposting in order that important information is not accidentally overlooked.
  • Print editions include tables of drugs known to have certain pharmacodynamic effects to make coverage more consistent. Digital platforms, such as MedicinesComplete and the BNF app, supply these details as messages between pairs of drugs.

The bigger picture

Since the 2015 relaunch of the BNF and BNFC, many users have found the interactions data more difficult to access and understand. This, coupled with changes to how interactions are studied and growth in the knowledge base, meant an overhaul was needed.

BNF Legacy products have not been updated with the new interactions, although they feature in the print editions of the BNF and BNFC that were distributed this autumn, the versions on the MedicinesComplete website, and the BNF app.

Extend your learning

  • Take a look at the BNF or BNFC and find the appendix that details interactions. What do you think of the changes?
  • Log onto MedicinesComplete and find prednisolone in the interactions section of the BNF. This looks slightly different to the print edition, with colour used to highlight certain drug clashes. Does this help you?
  • If a mobile device is used in your pharmacy, make sure the BNF app is installed on it and that it is up to date.


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