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Adverse Drug Reactions · PSA section guide

Adverse Drug Reactions in the PSA: what it tests, how it is marked, and a real question

Match a presentation to the medicine most likely to be causing it, or pick the drug most likely to produce a stated reaction.

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8items in the exam
2marks each
16 / 200of the paper
93questions in the bank

At a glance

Items in the exam8
Marks per item2
Share of the paper16 of 200
Question styleSingle best answer from five
Primary skillAttributing a presentation to a medicine
BNF useSide-effects, contra-indications, interactions
PassthePSA bank93 questions, rated easy to hard
On PassthePSASingle best answer in the exam's layout
Time at exam pace1 min 12 s

What this section is really testing

  • Timing: whether the symptom began after the drug, and whether the interval is plausible for that reaction.
  • Plausibility: whether the BNF lists the effect for that drug, and how commonly.
  • Competing causes: whether another drug or the disease itself explains the picture better.
  • Interactions: whether another medicine has raised the suspect's level or added to its effect.
  • Action: what should happen next, from stopping the drug to specific reversal.

A repeatable approach

  1. TimingDid the symptom start after the drug, and does the interval fit that reaction?
  2. PlausibilityIs the effect in the monograph's side-effects list, and at what frequency?
  3. Competing causesIs there a likelier explanation among the other drugs or the illness?
  4. InteractionsCould a second drug have pushed the first into toxicity?
  5. ActionStop, reduce, monitor, reverse. The BNF often states which.

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BNF strategy for this section

The exam is open book, and the time is short. Know which heading answers which question before you open the monograph.

Presentation→Suspect drug→Side-effects and frequency→Interactions→Action: stop / reduce / reverse
Does this drug cause this?
Side-effects, by frequency band
Is it a class effect?
The class page's side-effects list
Was something raising the level?
Interactions
Should it have been avoided?
Contra-indications and cautions
What now?
The side-effects section often gives the action; treatment summaries for poisoning where relevant

The general technique, with drills, is in the BNF speed guide.

The five questions, in order

TimingDid it start after the drug, at a plausible interval?
PlausibilityIs it in the side-effects list, and how common?
Competing causesAnother drug, or the illness itself?
InteractionsHas something raised the suspect's level?

Then the fifth: what should happen next. Dechallenge, dose reduction, monitoring or a specific reversal. The action is often the mark on its own.

Frequency is evidence

The BNF lists side effects by how often they occur. A symptom listed as very common for one drug on the chart and rare for the others is close to an answer on its own, provided the timing fits.

Common traps

Blaming the newest drug automaticallyTiming is the strongest clue, but only when the interval fits the reaction.
Can cause is not did causeAlmost every drug can cause a rash. The one listed as common, started at the right time, is the answer.
Missing the interactionThe drug is old and the dose unchanged; what changed is the macrolide started last week.
The disease did itFever in a septic patient is not a drug reaction until the drugs have been considered and excluded.
Stopping the wrong thingWhen the action is asked for, stop the culprit, not the drug that was treating the symptom.

Areas worth being comfortable with

Not predictions. These are the broad clinical areas this section draws on, taken from the shape of the exam and the BNF; being fluent in them makes the lookup fast.

  • Drug-induced electrolyte disturbance
  • Hepatotoxicity and cholestasis
  • Renal injury from common drugs and combinations
  • Blood dyscrasias and agranulocytosis
  • Serotonin syndrome, neuroleptic malignant syndrome and anticholinergic toxicity
  • Bleeding and bruising
  • Rashes, angioedema and anaphylaxis
  • Myopathy and rhabdomyolysis
  • Hypoglycaemia
  • Confusion and falls in older patients

A real adverse drug reactions question from the bank

This is one of the 20 items every visitor can try free, in the interface the exam uses. Work it before you open the answer.

ID : ADR-09Adverse Drug Reactions2 markseasy
Case presentation

A 62-year-old woman with atrial fibrillation attends for routine review. She has taken the same antiarrhythmic for several months and reports feeling increasingly tired, cold and constipated.

PMH: atrial fibrillation, hypertension.

DH: amiodarone 200 mg PO once daily, apixaban 5 mg PO twice daily, ramipril 5 mg PO once daily.

On examination: HR 58/min, dry skin, slow-relaxing reflexes.

Investigations: TSH 12 mU/L (0.4–4.0), free T4 8 pmol/L (10.0–22.0).

QuestionSelect the adverse effect most characteristically associated with long-term use of this antiarrhythmic.
(mark it with a tick)
ADVERSE EFFECT OPTIONS
  • gingival hyperplasia
  • hypothyroidism
  • nephrotoxicity
  • pancreatitis
  • peripheral oedema
Answer and marking
Correct answer

hypothyroidism

Marks

2

Explanation

Amiodarone commonly causes thyroid dysfunction (both hypo- and hyperthyroidism) because of its high iodine content; the raised TSH with low free T4 here indicates hypothyroidism. It also causes pulmonary, hepatic, corneal and skin effects, so thyroid and liver function are monitored.

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More free adverse drug reactions questions, each with its full explanation

ADR-89 · HardA 61-year-old with fever, sore eyes, a painful mouth and a spreading rash after an antibiotic2 marks →

Before you submit

  • Does the timing fit this reaction, not just any reaction?
  • Is the effect listed for this drug, and how commonly?
  • Have I excluded the other drugs and the illness?
  • Could an interaction be the real cause?
  • If an action is asked for, is it aimed at the culprit?

Practice questions

93 Adverse Drug Reactions questions, easy to hard, marked like the exam

Every answer comes with the explanation and the BNF reference behind it. Twenty questions across all eight sections are free. Pass guarantee: fail after 400+ questions and your access is extended free for 3 months.

Practise this section →Try the free 20-question sample

Continue revising

Prescription ReviewFinding the culprit drug in a realistic chart4 marks per item →Drug MonitoringKnowing what to measure, when, and what to do with it2 marks per item →Communicating InformationPrioritising the safety-critical advice2 marks per item →

View all 8 sections and the exam overview →

Section weightings follow the published PSA blueprint. The BNF headings named here are the current online BNF's. Check any dose or threshold against the BNF before you rely on it; this page teaches the method, the BNF holds the numbers.

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