Primolut-N Tablet contains norethisterone, a synthetic form of the hormone progesterone, used to regulate menstrual cycles, manage missed or irregular periods, and treat certain hormonal conditions. It works by restoring hormonal balance and supporting normal menstrual bleeding. Common side effects may include mild headache, nausea, breast tenderness, bloating, mood changes, or light spotting, which usually settle as the body adjusts. Rarely, more serious effects such as leg pain or swelling, chest pain, severe headache, shortness of breath, or allergic reactions may occur, and these require immediate medical attention. The medicine should not be used during pregnancy or by individuals with liver disorders, unexplained vaginal bleeding, or a history of blood clots. It must be taken only under medical supervision, and if irregular periods persist after treatment, further evaluation for underlying causes such as hormonal imbalance, thyroid problems, or polycystic ovary syndrome (PCOS) is advised.