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Table 1 Naranjo Adverse Drug Reaction Probability Scale

From: Ivermectin-induced fixed drug eruption in an elderly Cameroonian: a case report

Questions Yes No DK
1. Are there previous conclusive reports on this reaction? + 1
2. Did the adverse event appear after the suspected drug was administered? +2
3. Did the adverse reaction improve when the drug was discontinued or a specific antagonist was administered? + 1
4. Did the adverse event reappear when the drug was re-administered? 0
5. Are there alternative causes (other than the drug) that could on their own have caused the reaction? − 1
6. Did the reaction reappear when a placebo was given? + 1
7. Was the drug detected in blood (or other fluids) in concentrations known to be toxic? 0
8. Was the reaction more severe when the dose was increased or less severe when the dose was decreased? + 1
9. Did the patient have a similar reaction to the same or similar drugs in any previous exposure? + 1
10. Was the adverse event confirmed by any objective evidence? + 1
  1. The ADR is assigned to a probability category from the total score as follows: definite if overall score is 9 or greater, probable for scores 5–8, possible for scores 1–4, and doubtful if the score is 0
  2. ADR adverse drug reaction, DK do not know