How to undertake oral medicines calculations
Intended for healthcare professionals
how to series    

How to undertake oral medicines calculations

Jane Brindley Senior lecturer in adult nursing, School of Nursing, Faculty of Health and Wellbeing, Canterbury Christ Church University, Kent, England

Why you should read this article:
  • To enhance your knowledge of the procedures involved in oral medicines calculations

  • To understand the role of the nurse in reducing medication errors

  • To recognise the importance of local and national policies in protecting patients from harm

Rationale and key points

This article provides a step-wise, practical approach to undertaking oral medicines calculations for tablets, capsules and liquid preparations. It also explores the evidence base behind medication errors in relation to calculations.

•  Medication errors have been identified as one of the most frequent types of patient safety incident that occur, and they are the most common, single preventable cause of adverse events.

•  Undertaking a medicines calculation can reduce the risk of an incorrect medicines dose being administered to the patient, which would result in a suboptimal therapeutic benefit or possible harm to the patient.

•  Nurses must ensure that they practise undertaking medicines calculations, while healthcare organisations have an important role in ensuring this skill is developed and maintained among their staff.

Reflective activity

‘How to’ articles can help to update your practice and ensure it remains evidence-based. Apply this article to your practice. Reflect on and write a short account of:

1.  How this article might improve your practice when undertaking oral medicines calculations.

2.  How you could use this information to educate nursing students or your colleagues on the appropriate methods for undertaking oral medicines calculations.

Nursing Standard. doi: 10.7748/ns.2019.e11404

Peer review

This article has been subject to external double-blind peer review and checked for plagiarism using automated software


Conflict of interest

None declared

Brindley J (2019) How to undertake oral medicines calculations. Nursing Standard. doi: 10.7748/ns.2019.e11404


Please note that information provided by Nursing Standard is not sufficient to make the reader competent to perform the task. All clinical skills should be formally assessed at the bedside by a nurse educator or mentor. It is the nurse’s responsibility to ensure their practice remains up to date and reflects the latest evidence

Published online: 28 May 2019

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