According to WebMD, PMS symptoms last as long as seven days. These symptoms usually begin about five days before a woman's period and continue for two days after the period begins.
According to the Mayo Clinic, symptoms of PMS include pain, mood swings and acne. Although it is unclear what causes PMS, hormone changes before ovulation may play a part. Stress and exercise habits may also contribute to more severe and longer-lasting PMS symptoms. The Mayo Clinic explains that PMS is treated with over-the-counter pain medicine, oral contraceptives or an injection of Depo-Provera to stop ovulation. PMS may also be treated with anti-depressants.