Health experts are of the view that specific cause of PMS is not yet known. However, the studies support the fact that the shifts in hormones or hormonal changes that take place in the body of a woman are mainly responsible for occurrence of PMS.

The ovaries make two main hormones, estrogen and progesterone in a normal menstrual cycle. In the last week i.e. just before the menstruation begins, estrogen which was at the highest levels starts declining. And in the luteal phase the ovaries make progesterone.  Due to such changes in hormones the brain chemicals or neurotransmitters are affected which result in PMS.  These brain chemicals are GABA, serotonin, endorphins and neropinephrine. These neurotransmitters are affected with hormonal fluctuations resulting in mood swings, depression, fatigue, food cravings etc. Some studies also say that PMS might be due to imbalances in the levels of calcium and magnesium.

These two minerals are responsible for nerve cell communication and when the imbalances are there, it triggers PMS symptoms. Most women believe that stress leads to PMS. But this is not true. During PMS if there is stress, it can worsen the situation. But stress is not the cause of PMS. The studies are still going on in this field because exact causes of PMS are still not known.