Drug-induced hypersensitivity syndrome (DiHS) or drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a severe adverse drug-induced reaction characterized by various symptoms: skin rash, fever, lymph node enlargement and internal organ involvement, which starts within 2 weeks to 3 months after drug initiation. It is challenging to diagnose this syndrome due to the variety of cutaneous and visceral symptoms. Different mechanisms have been implicated in its development, including genetic susceptibility associated with human leucocyte antigen (HLA) loci, detoxification defects leading to reactive metabolite formation and subsequent immunological reactions, slow acetylation, and reactivation of human herpes, including Epstein-Barr virus and human herpes virus (HHV)-6 and HHV-7. The most frequently reported causes of DiHS/DRESS are antiepileptic agents, allopurinol and sulfonamides. We report a case of DiHS/DRESS induced by second-line treatment for tuberculosis, prothionamide and para-aminosalicylic acid, and Epstein-Barr virus re-infection. Patch testing, which was performed in this case, is not fully standardized, but it can be helpful and a safe way to evaluate and diagnose DiHS/DRESS.