Emergency Medicine General Medicine Pharmacology Moderate — widely used standardised causality assessment tool

Naranjo Adverse Drug Reaction Scale

Standardised questionnaire to assess the probability that an adverse drug reaction (ADR) is caused by a specific drug

1. Previous conclusive reports of this reaction?*

2. Did the adverse event appear after the drug was given?*

3. Did the reaction improve when the drug was stopped or an antagonist given?*

4. Did the reaction reappear when the drug was re-administered?*

5. Alternative causes that could solely have caused the reaction?*

6. Did the reaction reappear when a placebo was given?*

7. Was the drug detected in the blood (or other fluids) in toxic concentrations?*

8. Was the reaction more severe when the dose was increased, or less severe when decreased?*

9. Did the patient have a similar reaction to the same or similar drug before?*

10. Was the adverse event confirmed by objective evidence?*

References

Naranjo CA, et al. A method for estimating the probability of adverse drug reactions. Clin Pharmacol Ther. 1981;30(2):239–245.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Drugs

Pathways

Decision support only — verify against MDCalc, NICE, or your local guideline before clinical use.