They usually last 5-6 days, all women get grouchy when there on there periods, my boyfriend dousnt come near me when im on mine lol, PMS is related to changes in the body's hormones. As hormone levels rise and fall during a woman's menstrual cycle, they can affect the way she feels, both emotionally and physically. Some women, in addition to feeling more intense emotions than they usually do, notice physical changes along with their periods — some feel bloated or puffy because of water retention, others notice swollen and sore breasts, and some get headaches.
PMS usually goes away soon after a period begins, but it can come back month after month. Eating right, getting enough sleep, and exercising may help relieve some of the symptoms.Hope this helps :)