Foundations of Prescribing for Non-Medical Prescribers
Interactions, contraindications and high-risk medicines
Drug interactions, allergies, high-risk medicines, monitoring and escalation.
Learning objectives
• Differentiate drug-drug, drug-disease and drug-patient interactions. • Recognise contraindications, cautions and allergy information that change decisions. • Use high-risk medicines to practise systems-based safety thinking. • Plan monitoring and escalation where risk cannot be eliminated. • Avoid assuming electronic interaction alerts are complete or clinically decisive.
Why this matters
Drug interactions, allergies, high-risk medicines, monitoring and escalation.
Pre-prescribing foundation: this module develops knowledge and judgement for formal prescribing education; it does not authorise prescribing.
Learning outcomes
- Differentiate drug-drug, drug-disease and drug-patient interactions.
- Recognise contraindications, cautions and allergy information that change decisions.
- Use high-risk medicines to practise systems-based safety thinking.
- Plan monitoring and escalation where risk cannot be eliminated.
- Avoid assuming electronic interaction alerts are complete or clinically decisive.
Core concepts
Interactions may be pharmacodynamic, pharmacokinetic or disease-mediated; severity depends on the patient and therapeutic window.
Allergy history should distinguish immune-mediated reactions from predictable adverse effects and intolerance.
High-risk medicines deserve systems thinking: indication, baseline data, dosing, monitoring, interactions, transitions, patient education and rescue plans.
A checklist is useful only if it prompts reasoning rather than replacing it.
Safe prescribing decision pathway
- Define the clinical problem and whether prescribing is indicated.
- Gather the patient-specific assessment and diagnostic information needed.
- Check competence, professional authority and employer/service scope.
- Compare reasonable options using current authoritative sources.
- Agree the plan with the patient, including uncertainty and alternatives.
- Prescribe accurately only when the decision is justified.
- Document, monitor, review and safety-net.
Module emphasis: Identify the interaction or contraindication mechanism, assess patient-specific risk, check current authoritative guidance and define monitoring or an alternative plan.
Apply it
Scenario 1. A patient labelled “penicillin allergic” describes nausea only.
Reasoning prompt: Identify the interaction or contraindication mechanism, assess patient-specific risk, check current authoritative guidance and define monitoring or an alternative plan.
Scenario 2. An anticoagulant is prescribed with another medicine that raises bleeding risk.
Reasoning prompt: Identify the interaction or contraindication mechanism, assess patient-specific risk, check current authoritative guidance and define monitoring or an alternative plan.
Scenario 3. Lithium is continued despite dehydration and new interacting medication.
Reasoning prompt: Identify the interaction or contraindication mechanism, assess patient-specific risk, check current authoritative guidance and define monitoring or an alternative plan.
Common traps
- A patient who reports “allergy” can never receive any related drug.
- Interaction checkers make interaction assessment automatic.
- High-risk medicines are safe if the dose is technically correct.
Practice checklist
- What clinical problem am I trying to solve, and is prescribing indicated?
- What information is missing before a safe decision can be made?
- Is this within my current competence, professional authority and employer/service scope?
- Which current authoritative medicine or guideline source should I check?
- What patient-specific factors change benefit, harm, dose, route or monitoring?
- What will I document, monitor, review and safety-net?
- When should I seek supervision, pharmacy advice, specialist input or urgent escalation?
Optional reflection: Without entering identifiable patient or employer information, identify one capability you would need to strengthen before prescribing independently in this area.
Key points
- Interactions may be pharmacodynamic, pharmacokinetic or disease-mediated; severity depends on the patient and therapeutic window.
- Allergy history should distinguish immune-mediated reactions from predictable adverse effects and intolerance.
- High-risk medicines deserve systems thinking: indication, baseline data, dosing, monitoring, interactions, transitions, patient education and rescue plans.
- A checklist is useful only if it prompts reasoning rather than replacing it.
Official sources and further reading
Check current versions for time-sensitive decisions.
- BNF-01 - BNF / NICE: British National FormularyOpen official source
- MHRA-01 - MHRA: Yellow Card Scheme / Drug Safety UpdatesOpen official source
- NICE-01 - NICE: NG5 Medicines optimisationOpen official source
