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Contraindication checker

Q: What should I do if I have a condition that contraindicates my medication?

Contact your pharmacist or doctor immediately. Do not stop the medication without professional advice unless you are experiencing a serious adverse effect. Your prescriber may have already considered the contraindication and judged that the benefit outweighs the risk, or an alternative can be prescribed.

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Look up contraindications for any medication: conditions, situations or patient factors that make a drug unsafe or inadvisable. Covers absolute contraindications (must never use) and relative contraindications (use with caution). Always confirm with your pharmacist or doctor.

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Contraindications: absolute vs relative

A contraindication is a situation where a drug should not be used because the risk of harm outweighs any potential benefit. Understanding the difference between absolute and relative contraindications helps patients have better conversations with their healthcare team.

Absolute contraindications

Absolute contraindications are non-negotiable. Isotretinoin in pregnancy. Warfarin in the first trimester. MAOIs within 14 days of an SSRI. Metformin in severe renal failure (eGFR below 30). NSAIDs in patients with active peptic ulcer bleeding. In these situations, the drug must not be used, alternatives must be found.

Relative contraindications

Relative contraindications require a risk-benefit judgement. Beta blockers in asthma, generally avoided, but a cardioselective beta blocker may be used with close monitoring if no alternatives exist for a severe cardiac indication. NSAIDs in mild CKD, generally avoided but sometimes used short-term at low doses with monitoring. Your prescriber weighs up whether the benefit of the drug in your specific situation outweighs the known risk.

When to use the drug interaction checker alongside this tool

Contraindications cover conditions and patient factors. Drug-drug interactions are a separate concern. Use our Drug Interaction Checker to check for interactions between medications, and the Side Effect Checker to understand what to watch for once a drug is started.

Frequently asked questions

What is a contraindication?

A contraindication is a specific condition, situation or factor that makes it unsafe or inadvisable to use a particular medication. Absolute contraindications mean the drug must never be used. Relative contraindications mean the drug should be avoided unless the benefit clearly outweighs the risk with careful monitoring.

What is the difference between absolute and relative contraindications?

An absolute contraindication means the drug must not be used, the risk of harm is so high that no clinical benefit can justify it. A relative contraindication means the drug should be avoided but may be used with caution if alternatives are unavailable and benefits outweigh risks, with appropriate monitoring.

What should I do if I have a condition that contraindicates my medication?

Contact your pharmacist or doctor. Do not stop the medication without professional advice unless you are experiencing a serious adverse effect. Your prescriber may have already considered the contraindication and judged that the benefit outweighs the risk, or an alternative can be prescribed.