Premenstrual syndrome (PMS) is a combination of emotional, physical, psychological, and mood disturbances that occur after a woman's ovulation and typically ending with the onset of her menstrual flow. The most common mood-related symptoms are irritability, depression, crying, oversensitivity, and mood swings with alternating sadness and anger. The most common physical symptoms are fatigue, bloating, breast tenderness (mastalgia), acne, and appetite changes with food cravings. A more severe form of PMS, known as premenstrual dysphoric disorder (PMDD), also known as late luteal phase dysphoric disorder) occurs in a smaller number of women and leads to significant loss of function because of unusually severe symptoms.
How common is PMS? About 80% of women experience some premenstrual symptoms. The incidence of true PMS has often been overestimated by including all women who experience any physical or emotional symptoms prior to menstruation. It is estimated that clinically significant PMS (which is moderate to severe in intensity and affects a woman's functioning) occurs in 20% to 30% of women. About 2% to 6% of women are believed to have the more severe variant known as PMDD
What are the symptoms of PMS? A great variety of symptoms have been attributed to PMS. Women can have PMS of varying duration and severity from cycle to cycle. The most frequent mood-related symptoms of PMS include: •anger and irritability, •anxiety, •tension, •depression, •crying, •oversensitivity, and •exaggerated mood swings. The most frequent physical signs and symptoms of PMS include: •fatigue, •bloating (due to fluid retention), •weight gain, •breast tenderness, •acne, •sleep disturbances with sleeping too much or too little (insomnia), and •appetite changes with overeating or food cravings.
...enough said. http://www.medicinenet.com/premenstrual_syndrome/article.htm
