Norethisterone; Uses, Side Effects, Interactions, Pregnancy

Norethisterone; Uses, Side Effects, Interactions, Pregnancy

Norethindrone is a synthetic progestational substance with some anabolic, estrogenic, and androgenic properties. Norethindrone binds to the progesterone intracellular receptors in the reproductive system and the resultant activated complex interacts with specific DNA sites. This leads to an alteration in protein synthesis and results in an inhibition of LH release. Consequently, it inhibits ovulation and changes the normal cycle of cervical mucus and endometrium.

Norethindrone is a synthetic progestational hormone with actions similar to those of PROGESTERONE but functioning as a more potent inhibitor of ovulation. It has weak estrogenic and androgenic properties. The hormone has been used in treating amenorrhea, functional uterine bleeding, endometriosis, and for contraception.

Norethisterone, also known as norethindrone is a progestin medication which is used in birth control pills, menopausal hormone therapy, and for the treatment of gynecological disorders.

Mechanism of Action of Norethisterone

Progestins diffuse freely into target cells and bind to the progesterone receptor. Target cells include the female reproductive tract, the mammary gland, the hypothalamus, and the pituitary. Once bound to the receptor, progestins slow the frequency of release of gonadotropin-releasing hormone (GnRH) from the hypothalamus and blunt the pre-ovulatory LH surge.


Norethindrone shares the actions of progestins. Although the exact mechanism of action of progestin-only oral contraceptives is not known, norethindrone, when administered in usual contraceptive doses, appears to act principally by altering cervical mucus so that sperm migration into the uterus is inhibited. Progestational changes in the endometrium also occur which may inhibit implantation of the fertilized ovum in the uterus. In addition, continuous administration of low doses of norethindrone alters the rate of ovum transport by changing motility and secretion in fallopian tubes. Norethindrone prevents pregnancy even in the presence of ovulation. Norethindrone suppresses ovulation and causes ovarian and endometrial atrophy at high doses; the drug does not consistently suppress ovulation when administered in a continuous low-dose regimen. In low doses, norethindrone causes variable suppression of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Norethindrone has mild androgenic activity. At low doses, norethindrone also has some estrogenic activity.

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Indications of Norethisterone

  • Amenorrhea secondary
  • Dysfunctional Uterine Bleeding
  • Endometriosis
  • Endometriosis related pain
  • Estrogen deficiency
  • Postmenopausal osteoporosis
  • Vasomotor symptoms
  • Vulvovaginal atrophy
  • Use as a contraceptive,
  • Treat premenstrual syndrome,
  • Dysmenorrhea,
  • Menorrhagia,
  • Irregular menstruation,
  • Menopausal symptoms (in combination with estrogen), or to postpone a period.
  • It is also commonly used to help prevent uterine hemorrhage in complicated non-surgical or pre-surgical gynecologic cases and in treating nonresponsive cyclical mastalgia.
  • Oral contraceptives are indicated for the prevention of pregnancy in women who elect to use this product as a method of contraception
  • Indicated for the treatment of secondary amenorrhea, endometriosis, and abnormal uterine bleeding due to hormonal imbalance in the absence of organic pathologies, such as submucous fibroids or uterine cancer.

Contra-Indications of Norethisterone

  • Diabetes
  • Excessive fat in the blood
  • Porphyria
  • Overweight
  • Depression
  • Migraine Headache
  • Poor Vision
  • Optic Disk Edema
  • High blood pressure
  • Heart Attack
  • Lung embolism
  • Chronic Heart Failure
  • Stroke
  • Obstruction of a Blood Vessel by a Blood Clot
  • Blood Clot in Vein
  • Liver Problems
  • Kidney disease with reduction in kidney function
  • seizures
  • Visible water retention
  • Pregnancy
  • Increased cardiovascular event risk

Dosage of Norethisterone

  • Strengths: 0.35 mg; 5 mg

Abnormal Uterine Bleeding

  • 2.5 to 10 mg orally once a day
  • Duration of therapy: 5 to 10 days


  • 2.5 to 10 mg orally once a day
  • Duration of therapy: 5 to 10 days


  • 0.35 mg orally once a day


  • Initial dose: 5 mg orally once a day for 2 weeks
  • Maximum dose: 15 mg/day

Side Effects of Norethisterone

The most common

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More common

Less common

  • Abnormal dreams
  • change in sense of taste
  • congestion
  • discouragement, feeling sad, or empty
  • Acting on dangerous impulses
  • Aggressive or violent behavior
  • Thoughts about suicide or dying
  • New or worse depression
  • New or worse anxiety or panic attacks
  • Agitation, restlessness, anger, or irritability
  • Trouble sleeping
  • An increase in activity or talking more than normal

Drug Interactions of Norethisterone

Norethisterone may interact with following drugs, supplements & may decrease the efficacy of the drug

Pregnancy & Lactation of Norethisterone

FDA Pregnancy Category – X 


Birth control pills should not be taken by pregnant women. If you are taking birth control pills and discover that you are pregnant, stop the birth control pills and see your doctor. However, there is no conclusive evidence that the progestin contained in this medication will be harmful to the unborn child.

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If the use of birth control pills is started after breastfeeding has begun, there does not appear to be any effect on the quantity and quality of the milk. There is no evidence that progestin-only birth control pills such as this medication are harmful to the nursing infant. No side effects have been found on breastfeeding performance or on the health, growth, or development of the infant.




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