| Criterion | ICDRG Notation | Score |
| No reaction | 0 | 0 |
| Doubtful reaction | ± | 0.5 |
| Erythema and oedema | + | 1 |
| Erythema, oedema and vesicles | ++ | 2 |
| Severe reaction with blisters | +++ | 3 |