The Prescribing Safety Assessment is a mandatory pass for UK medical students before FY1. It tests practical prescribing competence — not pharmacology theory, but whether you can safely write a drug chart, spot a prescribing error, and choose the right drug at the right dose for a clinical scenario.
Most students overestimate its difficulty and over-prepare in the wrong areas. Here's the efficient approach.
The format
The PSA is a computer-based exam lasting 2 hours, with approximately 60 questions across 8 question types: prescribing (write a prescription), prescription review (spot and correct errors), planning management (choose the right drug), providing information (counsel the patient), calculation of dosages, adverse drug reactions, drug monitoring, and data interpretation.
You have access to a searchable BNF during the exam. This is the critical point that most preparation advice underemphasises: you don't need to memorise every drug dose. You need to know where to find it quickly and how to apply it correctly.
What actually fails people
Time pressure, not knowledge. 60 questions in 2 hours sounds generous until you're searching the BNF for the third time in the same question. Practise using the electronic BNF quickly — searching by drug name, by indication, and by interaction.
Calculation errors. Drug dose calculations (mg/kg, infusion rates, unit conversions) are the most common source of wrong answers. Practise the arithmetic by hand — no calculators in the real thing.
Prescribing format errors. Writing a prescription correctly (drug name, dose, route, frequency, duration, signature) sounds trivial but many candidates lose marks on format rather than drug choice.
Not reading the question carefully. "Which drug should be STOPPED" vs "which drug should be STARTED" — misreading the question is more common than not knowing the answer.
How to prepare
2–3 weeks is sufficient for most students. The PSA tests practical prescribing that you should already know from clinical placements. It's not a knowledge exam — it's a competence check.
Use the official PSA practice papers. The British Pharmacological Society publishes practice papers that are the closest thing to the real exam. Do all of them under timed conditions.
Practise BNF navigation. The electronic BNF you'll use in the exam is searchable but clunky. Spend time using it before exam day. Know how to find: drug doses, interactions, contraindications, and monitoring requirements — fast.
Know the common prescribing scenarios cold. Analgesia ladders (paracetamol → NSAIDs → weak opioids → strong opioids), antibiotic empirical choices (CAP, UTI, cellulitis), anticoagulation (warfarin bridging, DOAC dosing in renal impairment), insulin regimens, asthma step-up, and fluid prescribing. These constitute the bulk of the exam.
Know the high-risk drugs. Methotrexate (weekly, not daily), lithium (monitoring, interactions), warfarin (INR targets, interactions), insulin (unit errors), opioids (dose equivalence), and potassium (IV rate limits). These are the drugs that cause real-world prescribing errors and are tested repeatedly.
Calculations practice. Infusion rates, weight-based dosing, unit conversions (micrograms to milligrams, mL/hour to drops/minute). Do 20 practice calculations and you'll be fine. Skip this and you'll lose marks you shouldn't lose.
iatroX's clinical search covers BNF and NICE prescribing guidance and can be used for practice queries during your preparation (not during the exam itself, obviously).
The bottom line
The PSA has a high pass rate (~95%+) because it tests things you should know from clinical practice. It fails candidates who don't practise under timed conditions, who can't navigate the BNF efficiently, or who make arithmetic errors. Two weeks of focused preparation with official practice papers and BNF practice is all most students need.
iatroX offers AI clinical search covering BNF and prescribing guidance, plus a UK qbank for UKMLA and finals preparation. Built by a practising NHS GP.