Table 1.

Naranjo Adverse Drug Reaction Probability Scale for Allopurinol-Induced SJS

Assessment Questions	Yes	No	Do Not Know
1. Are there previous conclusive reports on this reaction?	+1	0	0
2. Did the adverse drug reaction appear after the suspected drug was administered?	+2	0	0
3. Did the adverse reaction improve when the drug was discontinued, or a specific antagonist was administered?	+1	0	0
4. Did the adverse event reappear when the drug was re-administered?	0	0	0
5. Are there alternative causes that could on their own have caused the reaction?	0	+2	0
6. Did the reaction reappear when a placebo was given?	0	0	0
7. Was the drug detected in blood (or other fluids) in concentrations known to be toxic?	0	0	0
8. Was the reaction more severe when the dose was increased or less severe when the dose was decreased?	0	0	0
9. Did the patient have a similar reaction to the same or similar drugs in any previous exposure?	+1	0	0
10. Was the adverse event confirmed by any objective evidence?	+1	0	0
Total score	8 = Probable