Premenstrual syndrome (PMS) is a group of physical, emotional, and behavioral symptoms that show up in the days or weeks before a period. It’s mainly driven by hormonal fluctuations, especially changes in estrogen and progesterone, which can affect the brain chemicals that regulate mood, appetite, and energy. That’s why PMS can cause bloating, breast tenderness, cramps, headaches, fatigue, acne, food cravings, irritability, low mood, or anxiety. Symptoms usually improve once the period starts an