TABLE 1.

Naranjo Adverse Drug Reaction Probability Scale (16)

Question	Yes	No	Do Not Know	Score*
Are there previous conclusive reports on this reaction?	+1	0	0	0
Did the adverse reaction appear after the suspected drug was administered?	+2	−1	0	+2
Did the adverse reaction improve when the drug was discontinued or a specific antagonist was administered?	+1	0	0	+1
Did the adverse reaction reappear when the drug was readministered?	+2	−1	0	+2
Are there alternative causes (other than the drug) that could on their own have caused this reaction?	−1	+2	0	+2
Did the reaction reappear when a placebo was given?	−1	+1	0	0
Was the drug detected in blood (or other fluids) in concentrations known to be toxic?	+1	0	0	0
Was the reaction more severe when the dose was increased or less severe when the dose was decreased?	+1	0	0	+1
Did the patient have a similar reaction to the same drug or similar drugs in any previous exposure?	+1	0	0	0
Was the adverse reaction confirmed by any objective evidence?	+1	0	0	+1
TOTAL SCORE:				9

^*Scale interpretation: definite if score is ≥9, probable if score is 5–8, possible if score is 1–4, and doubtful if score is 0 (16).