Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Stevens-Johnson syndrome ?
    ### Response:
    What causes Stevens-Johnson syndrome? The exact cause of Stevens-Johnson syndrome is unknown in 25 to 30% of cases. In those cases in which the cause can be determined, it is believed to be related to an adverse allergic drug reaction. Almost any drug--but most particularly sulfa drugs--can cause Stevens-Johnson syndrome.
    