Norethisterone: Presentation, Mechanism of Action, Indications, Dosage and Side Effects

Progestogens are synthetic medications that reproduce the effects of the hormone progesterone.

Norethisterone corresponds to a class of drugs known as progestogens. It is commonly known as a “progestin-only” or “mini-pill” pill.

Because it affects the hormonal control system of the body, it can contribute to the action of birth control ( contraceptives ).

Although its effectiveness is less than that of other contraceptive pills.

It is used to treat several conditions related to hormones and menstruation.


  • Tablets

Mechanism of action

Progesterone is a natural hormone of women whose levels fluctuate throughout the month.

A decrease in progesterone levels towards the end of the menstrual cycle contributes to the disintegration of the endometrium. Much of this lining of the uterus is expelled with vaginal bleeding.


When taking norethisterone, progestogen levels in the blood remain constant, stopping the process and preventing bleeding.


Due to the advantageous effects that can result from mimicking natural progesterone, norethisterone is used to treat various menstrual disorders.

These disorders include irregular periods, abundant periods, painful periods, absence of periods, endometriosis, and premenstrual syndrome.

It is also used to treat the symptoms of menopause as part of hormone replacement therapy.

Even in high doses, they have been used to treat some female cancers, such as breast cancer.


Take one tablet three times a day starting three days before your next period.

Norethisterone should be taken for less than 20 days.

The tablets can be taken with or without food. However, it is recommended to establish a routine of eating a tablet at breakfast, lunch, and dinner, as it ensures that the doses are distributed evenly throughout the day.

After stopping treatment, in 2-3 days, the menstrual cycle should usually resume.

Precautions and contraindications

Treatment with norethisterone can not be given if:

  • Cerebrovascular accident or myocardial attack, or any heart disease.
  • Infection, inflammation, or coagulation in any blood vessel or lungs.
  • Liver diseases (including tumors), Dubin-Johnson syndrome or Rotor syndrome, a history of jaundice or cholestatic jaundice of pregnancy, or severe generalized pruritus in the body during pregnancy.
  • Abnormal vaginal bleeding of unknown cause.
  • Pregnancy.
  • Cancer: vagina, ovaries, cervix, uterus, or estrogen-dependent tumors.
  • Family history of mammary nodules, fibrocystic diseases, or doubts due to abnormal mammography.
  • Sickle cell anemia.
  • Disorders of lipid metabolism.
  • Pregnancy history of herpes.
  • Otosclerosis.
  • Allergy to norethisterone or any of its components.
  • Renal disease.
  • High blood pressure and abnormal levels of cholesterol and triglycerides.
  • Diabetes.
  • Epilepsy.
  • Asthma.
  • Frequent migraines.
  • Depressive states
  • Lactose intolerance.

Side effects and risk factors

You may experience nausea, breast tenderness, fatigue, or headache.

Rarely, it can worsen some chronic diseases or interact with some medications.

However, you should go to the doctor immediately if you notice the following:

  • She was bleeding from disruption.
  • Changes in menstrual flow.
  • Absence of periods.
  • Changes in cervical secretions.
  • Change of vaginal secretions.
  • Changes in the breasts increase sensitivity and secretion.
  • Gastric or stomach discomfort, including nausea and vomiting.
  • Changes in body weight.
  • Fluid retention.
  • Spots accompany skin coloring on the face, arms, or legs, which may persist after stopping the tablets.
  • Rash with or without itching
  • Depression.

The most severe side effect known with norethisterone is the presence of abnormal blood clotting, which can have serious consequences such as blood clots transported by the bloodstream causing blockage of blood vessels in the lungs or the brain.

Risk factors for developing bleeding disorders increase with age and with tobacco.

The risk factors for a heart attack include cigarettes, high blood pressure, high cholesterol, obesity, diabetes, a history of toxemia preeclampsia in pregnancy, and over 40 years.

Reactions with other medications

Some medicines can interfere with the effectiveness of norethisterone:

  • Rifampicin is used for the treatment of tuberculosis.
  • Medications used to treat epilepsy include primidone, barbiturates, carbamazepine, and phenytoin.
  • Antibiotics such as ampicillin.
  • Antifungal agents such as griseofulvin.
  • If necessary, take an antacid while it should be taken at least 2 hours before administering norethisterone.


Symptoms of allergic reactions may include:

Asthma, difficulty breathing, swelling of the face, lips, or tongue can cause difficulty breathing or swallowing, hives, itching, and fainting.