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Norethisterone Synthetic Hormone


person taking pills

Norethisterone is a synthetic hormone made to mimic the hormone progesterone, which is produced naturally in the body. It is prescribed as a treatment for abnormal or unexpected bleeding from the uterus, symptoms of PMS, endometriosis, painful or heavy periods, or to postpone your period.


How does Norethisterone work?

The hormone progesterone is released during the second half of the menstrual cycle when an egg is released from the ovary. Progesterone prepares the body for pregnancy, maintaining the lining of the womb. When an egg has not been fertilized, progesterone production decreases, causing the lining of the womb to break away and your period to occur. If progesterone, or its synthetic equivalent, Norethisterone, is taken continuously, there is no drop in levels to trigger the shedding of the womb lining, and you will not have a period.


What are the side effects?

There are a number of side effects you may possibly experience when taking Norethisterone:

  • A rise in blood pressure
  • Jaundice (yellowing of skin or whites of the eyes)
  • Migraines
  • Itching
  • Abdominal pain
  • Dark brown urine
  • Nausea and vomiting
  • Allergic reaction (skin rash, swelling of face, lips, and tongue, difficulty swallowing or breathing)
  • Changes in eyesight, hearing, or speech

If you experience any of the above side effects, stop taking Norethisterone and contact your doctor. In the case of a severe allergic reaction, this is a medical emergency, and you MUST call an ambulance.

Other side effects you may experience:

  • Breakthrough bleeding
  • Breast pain and tenderness
  • Nausea
  • Tiredness or difficulty sleeping
  • Depression
  • Acne or worsening of existing skin conditions
  • Hair growth (especially on the top lip or chin)
  • Fluid retention, bloating, or weight gain
  • Changes in sex drive

If you experience any side effects, whether they are listed here or not, speak to your doctor.


Can you be allergic to Norethisterone?

As well as the active substance, Norethisterone, other ingredients in this medication are lactose, maize starch, and magnesium stearate. If you are allergic to any of these ingredients, do not take Norethisterone.


How should I take Norethisterone?

If you are prescribed Norethisterone, you would normally start taking it 3-4 days before you expect your period to begin. The prescription will consist of 3 tablets per day, which can take up to 20 days, depending on how long you wish to delay your period. Your period should arrive 2-4 days after you stop taking the medication. It is important to note that, as with the combined contraceptive pill, Norethisterone is unlikely to be considered suitable if you have a history of blood clots (thrombosis).

What precautions you should be taking

As with taking the combined oral contraceptive pill, the risk of developing blood clots in veins and arteries is slightly higher than in those women who don’t. If you have previously been advised that the combined pill is not suitable for you, neither will Norethisterone. Speak to your doctor about these possible risks and be aware that you are at greater risk if:

  • You smoke
  • You or any of your close family have had blood clots
  • Are overweight
  • Have a blood disorder
  • High blood pressure
  • Suffer from migraines
  • Recently had a baby
  • Have a disorder of blood fat metabolism
  • Diabetes (Norethisterone can produce changes in blood sugar levels)
  • You are off your feet for a long time (due to surgery, injury, or illness)
  • Suffer from certain medical conditions such as Systemic Lupus erythematosus, sickle cell, Crohn’s, or ulcerative colitis

Signs of a blood clot include:

  • Migraine (not experienced before or worse than normal)
  • Unusually frequent or severe headaches
  • Changes in eyesight, such as loss of or blurred vision
  • Sudden changes in hearing, speech, sense of smell, taste, or touch
  • Pain or swelling in your leg
  • Stabbing pain when breathing
  • Coughing for no apparent reason
  • Breathlessness
  • Pain ad tightness in the chest
  • Sudden weakness or numbness in one side or part of the body
  • Dizziness or fainting

If you notice any of these signs, stop taking Norethisterone and speak to your doctor or call NHS 111 for urgent advice.

When seeking a prescription for Norethisterone, also inform your doctor if you suffer from or have previously suffered from depression, epilepsy, kidney problems, have an intolerance to some types of sugar, are pregnant or breastfeeding, have breast cancer, or had it in the past.


How does Norethisterone interact with other medications?

Inform your doctor of any medication, treatments, or supplements you are taking or have recently taken, as they may negatively interact with Norethisterone. Some of these treatments are:

  • Other hormonal products
  • Medicines for epilepsy
  • Some antibiotics
  • St John’s Wort
  • Other medications which can cause fluid retention (e.g., ibuprofen)

Before taking any medication, read the patient information leaflet in full and if you have any concerns, speak to your doctor.


Find out more health information 

Knowing how to spot the signs and symptoms of illness is essential when it comes to diagnosis and treatment. Home Health provides testing kits and treatments for female health conditions and infections, including feminine care and hygiene products. Ensure both you and your pet are healthy and happy by staying informed of all the important health information on our website.