Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. I Can understand your discomprt.dealy in menstrual bleeding while on menstrual bleeding while on Primolut N.It’s common thing No need to worry. What comes out during your period is the blood and tissue that build up as the lining of your uterus each month. Your period flow can be light, heavy, or in between. Sometimes menstrual blood also will be different shades of red, from light to dark. You may see some dark clumps or clots of blood, which is normal. The usual length of menstrual bleeding is four to six days. The usual amount of blood loss per period is 10 to 35 ml. Each soaked normal-sized tampon or pad holds a teaspoon of blood . That means it is normal to soak one to seven normal-sized pads or tampons (“sanitary products”) in a whole period. Primolut N is used to treat menstrual disorders such as irregular periods, painful periods (dysmenorrhoea), endometriosis and menopausal symptoms. Primolut N can also be used to delay menstrual bleeding. Major & minor side effects for Primolut N Tablet 1. Irregular menstrual periods. 2. Enlargement of breasts. 3. Stomach discomfort and pain. 4. Weight loss or weight gain. 5.Trouble sleeping. 6. Acneiform eruptions. Because the active ingredient in Primolut N, norethisterone, is converted to oestrogen in the body, some of the information in this leaflet is based on experience with oestrogen containing oral contraceptives. However, Primolut N is not to be used as a contraceptive. It will not prevent you from falling pregnant. Hope I have answered your query. Let me know if I can assist you further.