Primosiston: What Is It For & How to Take It

Updated in December 2023

Primosiston is a medication that can be used to stop uterine bleeding. It is also widely used to delay menstruation or to influence the cycle to initiate it earlier. This medication is available at pharmacies with a prescription.

This medication contains norethisterone acetate 2 mg and ethinyl estradiol 0.01 mg as active ingredients, which are capable of preventing ovulation and affecting hormone production. It acts by modifying the lining of the uterus (the endometrium) to stop its monthly shedding and bleeding.

While using primosiston, vaginal bleeding gradually ceases and within 5 to 7 days it should completely disappear. Besides using primosiston, there are other techniques that can be used to stop your period.

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What is it for

Primosiston is most commonly prescribed for the treatment of uterine bleeding and to delay menstruation. It can also be used to influence the cycle to have your period start earlier. This medication prevents ovulation and affects hormone production, which modifies the uterine lining and stops period bleeding.  

Can primosiston be used as birth control? 

Although it contains contraceptive hormones in its formulation, primosiston is not a birth control method and therefore should not be used to prevent pregnancy. Learn about the different methods of birth control

How to take it 

The use of Primosiston is indicated in the following ways:

To stop bleeding caused by dysfunctional uterine bleeding

The recommended dose is 1 pill, 3 times a day for 10 days, which can stop uterine bleeding within 1 to 4 days when it is not associated with any injury to the uterus.

Although it is variable, bleeding usually subsides within the first few days from the start of treatment, but it can last for 5 to 7 days before it stops completely. In cases where the woman wishes to stop a longer-lasting period (e.g. over 8 days), it is important to talk to the gynecologist to identify the cause. 

To start menstruating sooner 

Take 1 pill, 3 times daily for at least 8 days starting on the 5th day of your menstrual cycle. The first day of your menstrual cycle is the first day of your period. In this case, menstruation usually occurs 2 to 3 days after discontinuation of the medication.

To delay menstruation:

Take 1 pill, 3 times a day for 10 to 14 days, taking the 1st pill 3 days before the scheduled date of your next period. In this case, before use, it is very important that you make sure that there is no pregnancy, for safe use, without risking the baby's health.

Possible side effects

Primosiston is generally well-tolerated, but sometimes unpleasant symptoms can emerge, like headache, nausea, a feeling of breast tension and an upset stomach. Taking more pills than you should, may cause symptoms such as nausea, vomiting and vaginal bleeding.

This medication can also interfere with the action of oral anti-diabetic medication and is therefore not recommended for diabetic women. It can also cause angioedema, especially in people with a family history of it. Therefore, you should stop treatment and proceed to the emergency room if you develop symptoms like itchiness, blisters, difficulty breathing, coughing, chest pain, throat or mouth swelling, or swelling of the face or tongue. 

Who should not take it

Primosiston should not be used by pregnant or breastfeeding women, by women with an allergy to its components, or by women with  breast cancer.

It should be used with caution if there is a history of heart disease, sickle cell anemia, stroke, or liver disease. It may interfere with the action of oral diabetic medication, and therefore it is also not recommended for women with diabetes. 

In addition, Primosiston contains reproductive hormones but should not be considered a contraceptive and therefore the use of condoms is recommended during all intimate contact.