Patch testing may help to assess the culpability of a drug in an adverse 
reaction. Our aim was to study patch testing in severe cutaneous adverse drug 
reactions (ADRs) (Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN), 
acute generalized exanthematous pustulosis (AGEP), and other cutaneous ADRs). 59 
patients with cutaneous ADRs were included: 22 had SJS/TEN, 14 AGEP, and 23 
other cutaneous ADRs. Patients were patch tested with the suspect drug, and with 
a standard series of drugs. 2 patients among the 22 SJS/TEN cases had a relevant 
positive test. 7 patients among the 14 AGEP cases had a relevant positive test. 
6 patients among the 23 other cutaneous ADRs had a relevant positive test. Our 
results suggest that patch testing has a weak sensitivity in SJS/TEN and is not 
appropriate in these diseases. Patch testing seems more adapted to other 
cutaneous ADRs, such as AGEP, in which the proportion of positive patch tests 
was significantly higher (p < 0.02). Nevertheless, the difference of sensitivity 
of patch testing in SJS/ TEN, AGEP or other cutaneous ADRs could be linked not 
only to the clinical type of eruption, but also to the different spectrum of 
culprit drugs in each type of eruption.