Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Premenstrual Syndrome ?
    ### Response:
    Premenstrual syndrome, or PMS, is a group of symptoms that start one to two weeks before your period. Most women have at least some symptoms of PMS, and the symptoms go away after their periods start. For some women, the symptoms are severe enough to interfere with their lives.
    