CBC with diff
BMP
LFTs
Coags
ESR
CRP
Viral hepatitis panel
Biopsy
Drug rash with eosinophilia and systemic symptoms syndrome
Positive Nikolsky’s sign
Jarisch-Herxheimer reaction
Febrile
Staphylococcal scalded skin syndrome
Staphylococcal scalded skin syndrome 
Immune reconstitution inflammatory syndrome
Toxic epidermal necrolysis/SJS 