What is the BNF and how do you access it?
The British National Formulary is published jointly by the BMJ Group and the Royal Pharmaceutical Society. It is the reference most UK prescribers, pharmacists and nurses use every day. The BNF for Children (BNFC) covers medicines from birth to 18 years. Both are available online (free for UK users through the NICE website) and as an app, and many hospital electronic prescribing systems link to them.
The online BNF is updated regularly, so it is the version to trust. Printed copies go out of date, and a well-thumbed book from a previous job or another country can mislead you.
How do you read a BNF drug monograph?
Each medicine has a monograph. Work through it in a consistent order rather than jumping straight to the first dose you see.
| Section | What to look for |
|---|---|
| Indications and dose | The dose for your indication, route and age group; doses often differ by indication |
| Unlicensed use | Whether your intended use is outside the product licence |
| Contraindications and cautions | When to avoid the drug or use it carefully |
| Interactions | A link to the interactions section listing interacting drugs and how serious each interaction is |
| Side effects | Common and serious adverse effects to warn about and monitor |
| Pregnancy and breast feeding | Specific advice for each |
| Hepatic and renal impairment | Dose changes and when to avoid |
| Monitoring requirements | Blood tests, drug levels or observations needed |
| Directions for administration | How to give it, including dilution and infusion rates for some injections |
| Medicinal forms | Available preparations and strengths |
The BNF also has treatment summaries for conditions, general guidance on prescribing (including prescribing in renal impairment, in the elderly and in palliative care) and guidance on prescription writing. It is worth reading these sections once, early in your first UK job.
How do you check a dose in kidney impairment?
Renal dosing is one of the commonest reasons pharmacists change a new prescriber's chart. Many drugs, including some antibiotics, low molecular weight heparins and opioids, accumulate when kidney function is poor.
Hassan, an FY1, needs to prescribe the antibiotic recommended by the trust guideline for a 79-year-old woman with a chest infection and an eGFR of 25. He opens the BNF monograph, reads the dose for the correct indication, then checks the renal impairment section, which advises a lower dose below a certain level of kidney function. The BNF notes that for some drugs, especially in older or low-weight patients, creatinine clearance should be used rather than eGFR. He asks the ward pharmacist to help calculate it, they agree a reduced dose, and he documents the reason in the notes.
- Check the latest kidney function: Look at today's results, not last week's. Kidney function can change quickly in acute illness.
- Read the renal impairment section: Note the thresholds and whether the BNF refers to eGFR or creatinine clearance.
- Calculate if needed: Use weight and the approved method for creatinine clearance where advised, especially at extremes of weight or age.
- Ask a pharmacist: For narrow-margin drugs or uncertainty, get advice before prescribing.
- Document and review: Record why the dose was adjusted and review it when kidney function changes.
How do you check drug interactions in the BNF?
The BNF interactions section lists interacting medicines for each drug and indicates how serious each interaction is and the strength of the evidence behind it. For a severe interaction, the usual message is to avoid the combination or to monitor closely and adjust doses. Check interactions against the patient's whole medicines list, including over-the-counter and herbal products such as St John's wort.
Electronic prescribing systems also raise interaction and allergy alerts. Read every alert. If you override one, record why. Alert fatigue, where prescribers click through warnings without reading them, is a recognised cause of harm.
What are the UK rules for writing a prescription?
Whether you write on paper or in an electronic system, prescriptions must be clear, complete and unambiguous. These conventions come from the BNF's guidance on prescription writing.
| Convention | Write | Avoid |
|---|---|---|
| Approved (generic) names | Amoxicillin | Brand names, unless clinically important (some modified-release products, inhalers, antiepileptics) |
| No trailing zero | 3 mg | 3.0 mg (misread as 30 mg) |
| Leading zero | 0.5 mL | .5 mL (misread as 5 mL) |
| Grams and milligrams | 1 g; 500 mg | 0.5 g |
| Micrograms and nanograms in full | 100 micrograms | mcg, µg or ug |
| Units in full | 10 units | U or IU (misread as 0 or 4) |
| Clear frequency | Twice daily, or 08:00 and 20:00 | Unapproved Latin abbreviations |
| Full as-required instructions | Paracetamol 1 g oral, every 4 to 6 hours as required for pain, max 4 g in 24 hours | Paracetamol PRN |
Morphine 5-10mg PRN. Insulin 10U. Enoxaparin. Tramadol.
Morphine sulfate oral solution 2.5 mg to 5 mg, oral, every 4 hours as required for moderate to severe pain, maximum 6 doses in 24 hours (opioid-naive, eGFR 48; reviewed with pharmacist). Insulin aspart 10 units subcutaneously with breakfast. Enoxaparin 40 mg subcutaneously once daily at 18:00 for VTE prophylaxis (weight 72 kg, eGFR 48, platelets normal). [Name, FY1, bleep, date]
Every prescription also needs patient identifiers, documented allergy status (with the type of reaction, and 'no known drug allergies' actively recorded), weight where relevant, an indication and review date for antibiotics, and your signature, name, role and contact details. For children, always use the BNFC, record the weight and double-check calculations; tenfold errors are a particular risk.
Controlled drugs and other high-risk medicines
Controlled drugs are regulated under the Misuse of Drugs Act 1971 and the Misuse of Drugs Regulations 2001. Prescriptions for Schedule 2 and 3 drugs that will be dispensed (community and discharge prescriptions) must include the patient's name and address, the drug's form and strength, the dose, the total quantity in words and figures, and the prescriber's signature, date and address. Schedule 2, 3 and 4 prescriptions are valid for 28 days. Inpatient charts follow local policy.
Oxycodone 5 mg PRN, 1 week.
Oxycodone hydrochloride 5 mg capsules (immediate release). Take ONE capsule (5 mg) by mouth every 4 to 6 hours when required for pain, maximum 4 capsules in 24 hours. Supply: 28 (twenty-eight) capsules.
- Distinguish immediate-release from modified-release opioids, and prescribe modified-release by brand where local policy requires.
- Check the current opioid dose before changing it, and use the BNF or palliative care guidance for conversions.
- Prescribe a laxative with regular opioids unless there is a reason not to.
- Take care with insulin, anticoagulants, IV potassium, aminoglycosides and antiepileptics.
- Oral methotrexate for non-cancer conditions is usually weekly; state the day clearly.
- Give time-critical medicines, such as those for Parkinson's disease, at the patient's usual times.
Electronic prescribing traps and questioning prescriptions
| Trap | How to avoid it |
|---|---|
| Wrong drop-down selection (wrong strength or modified-release) | Read the whole line before selecting |
| Wrong patient record | Close one record before opening another; check identifiers |
| Duplicates (regular and as-required, or two names) | Review the full active list before adding |
| Free text conflicting with structured dose | Use structured fields and keep free text consistent |
| Hidden one-off or future orders | Learn how your system displays them |
The system does not know that the patient became nil by mouth today or bought ibuprofen over the counter. Clinical judgement stays with you. Ask for training on your trust's system before your first shift.
Nurses and pharmacists share responsibility for medicines safety. If a prescription seems wrong, do not give or dispense it until clarified: contact the prescriber, explain the concern specifically and record the outcome. Prescribers who are questioned should thank the person and recheck with an open mind. If you make or find an error, make the patient safe, inform the responsible clinician, be open with the patient if it reached them, and report it, including near misses.
Learning more
Use the BNF alongside local antimicrobial guidelines, your trust formulary, the Summary of Product Characteristics, injectable medicines guidance and your ward or on-call pharmacist. Doctors in their first UK post may need to pass the Prescribing Safety Assessment or a local equivalent, so check what your employer requires. For a structured course covering the BNF, prescription conventions, controlled drugs, electronic systems and medicines reconciliation, with worked examples and a reflective exercise for your CPD record, see Prescribing in the UK: BNF and Electronic Systems. Your First NHS Job: Induction and Expectations and Your First Week on the Ward cover the wider practicalities of starting.
Frequently asked questions
Is the BNF free to use in the UK?
Yes, for most UK users. The BNF and BNF for Children are available free online through the NICE website and through the official app for people in the UK. Many hospital systems also link directly to them. Use the online version rather than an old printed copy, because content is updated regularly.
What is the difference between the BNF and the BNFC?
The BNF covers medicines mainly for adults. The BNF for Children covers prescribing from birth to 18 years, with weight- and age-based doses and paediatric formulations. Always use the BNFC for children, record their weight, and double-check calculations, as tenfold dosing errors are a particular risk.
Should I use eGFR or creatinine clearance for renal dosing?
It depends on the drug and the patient. The BNF advises using creatinine clearance rather than eGFR for some medicines, particularly in older people and those at extremes of body weight, and for drugs with a narrow therapeutic margin. Check the monograph and ask a pharmacist to help with the calculation if unsure.
How do I check drug interactions in the BNF?
Open the interactions section for the drug, or follow the link from its monograph, and check each of the patient's other medicines, including over-the-counter and herbal products. The BNF indicates how serious each interaction is and the strength of the evidence. For serious interactions, avoid the combination or monitor and adjust, and ask a pharmacist.
Can I prescribe in the UK if I was a prescriber abroad?
Not until you are registered with the relevant UK regulator. Doctors need GMC registration with a licence to practise. Nurses, pharmacists and allied health professionals also need a prescribing annotation on their UK registration after completing an approved programme. Check your status on the register before prescribing anything.
What must a controlled drug prescription include?
For Schedule 2 and 3 drugs that will be dispensed, include the patient's name and address, the drug's form and strength, the dose, the total quantity in both words and figures, and the prescriber's signature, date and address. These prescriptions are valid for 28 days. Inpatient drug charts follow local policy.
Why should I write micrograms and units in full?
Abbreviations such as mcg, µg, U and IU are easily misread. 'U' can look like a zero or a 4, turning 10 units into 100 or 40, and 'µg' can be read as mg, a thousandfold error. The BNF's prescription-writing guidance advises writing these words in full.
Related courses
Prescribing in the UK: BNF and Electronic Systems
This course is a practical guide to prescribing and checking prescriptions in the UK for new starters and internationally educated professionals. It…
Your First NHS Job: Induction and Expectations
This course is a practical guide to your first weeks in an NHS job, written for newly qualified staff and for professionals who trained outside the…
Your First Week on the Ward
This course is a practical survival guide for doctors and nurses starting on a UK hospital ward. It explains how ward rounds, jobs lists, bleeps and…
Sources and further reading
- British National Formulary and BNF for Children, including guidance on prescription writing. BMJ Group and Royal Pharmaceutical Society.
- Good practice in prescribing and managing medicines and devices. General Medical Council.
- A competency framework for all prescribers. Royal Pharmaceutical Society.
- Professional guidance on the administration of medicines in healthcare settings. Royal Pharmaceutical Society and Royal College of Nursing.
- Medicines optimisation (NG5). National Institute for Health and Care Excellence.
- Controlled drugs: safe use and management (NG46). National Institute for Health and Care Excellence.
- The Misuse of Drugs Regulations 2001. legislation.gov.uk.
Practitioner Insight is an independent education provider. It is not affiliated with or endorsed by the GMC, MPTS, NMC, HCPC, GPhC or any NHS organisation, and this information is not legal advice. If you have been referred to a regulator, speak to your defence organisation, trade union or legal representative.
More guides
Paediatric Dose Calculations: Worked Examples and How to Avoid Errors
Paediatric dose calculation worked examples: mg/kg doses, divided daily doses, micrograms, maximum doses and infusion rates, plus how to avoid tenfold errors.
Controlled Drugs in the UK: Schedules, Registers and Safe Handling
Controlled drug schedules 1 to 5 explained, plus CD register rules, safe storage, witnessing, stock checks and what to do about a discrepancy in UK practice.
Dispensing Errors in Pharmacy: What to Do and How to Prevent Them
What to do after a dispensing error in pharmacy: making the patient safe, apologising, reporting, the legal defences, near-miss logs and practical prevention.