Safe prescribing basics

Why this matters on day one

Prescribing is the commonest thing an FY1 does and the commonest source of harm they cause. Most errors are not diagnostic — they are a missing allergy box, a wrong units abbreviation, or a drug continued long after the reason for it ended.

The sequence

1. 1Every prescription. Approved (generic) name, dose, route, frequency, start date, your signature and a printed name plus contact. Write micrograms and nanograms IN FULL. Never a trailing zero ("2 mg", not "2.0 mg"). Always a leading zero ("0.5 mg", not ".5 mg"). Units, not "U".
2. 2Before you sign. Allergy status and what the reaction was. Weight for anything weight-based. Renal and hepatic function. Pregnancy and breastfeeding. Current drug chart — including things bought over the counter and herbal remedies, which patients do not classify as medicines.
3. 3Indication and duration. Write the indication for antibiotics and a stop or review date. An antibiotic with no duration becomes indefinite. The same applies to PPIs, opioids and sedatives.
4. 4Check the interactions. Use the BNF interaction checker rather than memory. Particular care: warfarin and DOACs, methotrexate, lithium, digoxin, phenytoin, and anything CYP-inducing or -inhibiting.
5. 5Communicate it. Tell the patient what you have started, why, what it may do to them, and what to report. Tell the nurse if it is urgent or time-critical — a written stat dose is not a delivered one.

What goes wrong

• "U" for units and "mcg" handwritten as "mg" — the two classic tenfold errors.
• Copying the previous chart forward without reviewing whether each drug is still indicated.
• Prescribing weight-based doses on an estimated weight.
• Missing the time-critical drugs: Parkinson's medication, insulin, anticonvulsants, and steroids. A late levodopa dose causes real harm within hours.
• Not documenting an allergy you have just been told about.