Norethindrone

1 medicine

Norethindrone is a progestin used in progestin-only contraceptive pills and to treat abnormal uterine bleeding and endometriosis. Any undiagnosed vaginal bleeding must be checked by a doctor before starting it, and it raises the risk of blood clots.

Aygestin

Norethindrone

5mg

Aygestin is a womens health medication containing Norethindrone, available as 5mg tablets.

from $0.86 / tablet View

Key facts

  • Norethindrone is a progestin, a synthetic form of the hormone progesterone. It is the active ingredient in progestin-only contraceptive pills and in tablets (such as Aygestin) used for abnormal bleeding and endometriosis.
  • As a contraceptive it is taken at the same time every day without a break; being even 3 hours late can reduce its effectiveness. For other uses it is typically taken once or twice daily as directed.
  • Any unexplained or undiagnosed vaginal bleeding must be evaluated by a doctor before starting norethindrone, since it can mask an underlying condition that needs its own treatment.
  • Seek urgent care for calf pain and swelling, sudden chest pain or breathlessness, or a severe headache with vision changes, which can signal a blood clot.

What norethindrone treats

Norethindrone is used as a progestin-only method of contraception, suitable for people who cannot take oestrogen. Higher doses treat abnormal uterine bleeding, secondary amenorrhoea (absent periods), and endometriosis, where it suppresses growth of the uterine lining and endometrial tissue outside the uterus. It is also added to oestrogen in menopausal hormone therapy to protect the uterine lining from overgrowth.

How norethindrone works

Norethindrone mimics natural progesterone. It thickens cervical mucus to block sperm, can suppress ovulation, and thins the uterine lining so it is less likely to support a pregnancy or to grow abnormally. In endometriosis, the same lining-suppressing effect reduces the tissue that causes pain and bleeding.

Before you take it

  • Do not take norethindrone if you have current or past breast cancer, undiagnosed vaginal bleeding, active liver disease, or a history of blood clots in the legs or lungs.
  • Tell your prescriber if you smoke, are over 35, or have migraine with aura, high blood pressure, or diabetes, since these raise clotting risk further.
  • It does not protect against sexually transmitted infections.
  • Rifampicin, certain anti-seizure medicines, and St John's wort can reduce its effectiveness; a backup contraceptive method may be needed.

Side effects

Common effects include irregular spotting, breast tenderness, headache, nausea, and mood changes, which often settle after the first few months.

Stop and seek urgent medical care for any of these:

  • Leg pain, swelling, or warmth (possible clot).
  • Sudden chest pain, breathlessness, or coughing blood.
  • Severe headache, sudden vision loss, or slurred speech.
  • Yellowing of the skin or eyes.

Safety essentials

  • Norethindrone increases the risk of venous blood clots (deep vein thrombosis and pulmonary embolism); the risk is lower than with combined oestrogen-progestin contraceptives but rises with smoking, obesity, immobility, and a personal or family clotting history.
  • Report any new or worsening abnormal vaginal bleeding while on treatment; it needs medical review rather than simply increasing the dose.
  • If a dose is missed by more than 3 hours (contraceptive use), follow the backup-contraception instructions in the product leaflet.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.