Premenstrual syndrome (PMS) refers to physical and emotional symptoms that occur 5-11 days before a woman's menstrual period begins. About 85% of women experience mild PMS symptoms, while some have more severe symptoms that impact work or relationships. PMS is caused by fluctuations in estrogen and progesterone levels before menstruation. Common symptoms include cravings, acne, pain, mood swings, sleep issues, and other issues. Keeping a daily symptom diary can help diagnose PMS. Lifestyle changes and medications may relieve symptoms.