Norethindrone Acetate

Norethindrone acetate is a prescription hormone medication called a progestin. It is FDA-approved to treat:

• Endometriosis (tissue similar to the uterine lining growing outside the uterus)
• Abnormal uterine bleeding caused by a hormonal imbalance
• Secondary amenorrhea (absence of menstrual periods not caused by pregnancy)

It is also commonly prescribed off-label to protect the uterine lining (endometrium) in women taking estrogen as part of hormone replacement therapy (HRT) for menopause.

How to take it

• Take the tablet by mouth, with or without food.
• Take it at the same time each day.

Your dose and how long you take it will depend on your condition. Do not change your dose or stop taking this medication without talking to us first.

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and go back to your regular schedule. Do not double up.

Why a progestin is needed with estrogen during HRT

If you have a uterus and take estrogen for menopausal symptoms (such as hot flashes), taking estrogen alone can cause the uterine lining to thicken too much. This increases the risk of endometrial hyperplasia (abnormal thickening) and, over time, uterine cancer. Adding a progestin like norethindrone acetate protects the lining and greatly reduces this risk.

What to expect with your periods

Norethindrone acetate will likely change your menstrual bleeding pattern. What happens depends on why you are taking it and how it is prescribed. These changes are a normal part of how the medication works — but it is important to know what is expected so you can tell the difference between a normal change and something that needs attention.

If you are taking it for abnormal uterine bleeding or missed periods (short course, 5–10 days)

• You will usually get a period (called "withdrawal bleeding") about 3 to 7 days after you finish the course of pills.
• This bleed is typically lighter and shorter than a normal period.
• If you do not get a period after finishing the course, let us know — we may want to check for other causes.
• We may prescribe repeated short courses to help regulate your cycle over time.

If you are taking it continuously for endometriosis (daily, for months)

• The goal of treatment is to stop or greatly reduce your periods. Many women stop having periods entirely while on this medication, which is expected and not harmful.
• During the first few weeks or months, you may have irregular spotting or breakthrough bleeding. This is common and usually improves over time.
• If breakthrough bleeding becomes heavy or persistent, we may temporarily stop the medication or adjust your dose.
• Your regular periods should return after you stop taking the medication, though it may take a few weeks to a few months.

If you are taking it as part of hormone replacement therapy (HRT) for menopause

Your bleeding pattern depends on whether you take the progestin continuously or cyclically:

• Continuous use (taking it every day along with estrogen): Many women will transition to have no periods at all. However, some irregular spotting or light bleeding is common during the first 3 to 6 months. This usually decreases over time. In studies, the majority of women had little to no bleeding after the first few months of continuous use.
• Cyclical use (taking it for 12–14 days each month): You will likely have a predictable, period-like withdrawal bleed each month after you finish the progestin days. This bleed is usually lighter than a natural period.

When to contact us about bleeding

• Bleeding that is very heavy (soaking through a pad or tampon every hour for several hours)
• Bleeding that starts after you have had no periods for several months on continuous HRT — especially if it occurs after the first year of treatment
• Bleeding that is accompanied by severe pain, dizziness, or feeling faint
• Any bleeding pattern that feels unusual or concerns you

Common side effects

Many side effects are mild and may improve as your body adjusts. Common side effects include:

• Breakthrough bleeding or spotting
• Changes in your period (lighter, heavier, or no period)
• Headache or migraine
• Nausea
• Bloating or weight changes
• Breast tenderness or swelling
• Mood changes, including feeling down or irritable
• Acne
• Trouble sleeping
• Skin darkening (melasma), especially on the face

Blood clots

Tell us if you have a personal or family history of blood clots, or other risk factors such as smoking, obesity, or prolonged immobility — this medication can increase the risk of clots, so we go over this with you before you start. Warning signs to act on are listed under "When to seek emergency care" below.

Who should not take norethindrone acetate

Do not take this medication if you:

• Are pregnant or think you may be pregnant
• Have unexplained vaginal bleeding that has not been evaluated
• Have or have had breast cancer
• Have a history of blood clots (deep vein thrombosis or pulmonary embolism)
• Have had a recent stroke or heart attack
• Have liver disease or liver tumors
• Are allergic to norethindrone or any ingredient in the tablet

Let us know if you have or have ever had:

• Depression or mood disorders
• Epilepsy or seizures
• Migraines
• Heart, kidney, or liver problems
• Diabetes or high cholesterol
• A history of blood clots or clotting disorders
• A family history of blood clots

Also tell us about all medications, vitamins, and supplements you take, as some drugs may interact with norethindrone acetate.

Other things to know

• This medication may cause fluid retention. Report sudden weight gain or swelling to us.
• If you need any lab tests or biopsies, let the lab know you are taking this medication, as it can affect certain test results.
• If you are taking this medication as part of HRT, we will periodically reassess whether you still need it.
• Store at room temperature (68°F to 77°F). Keep out of reach of children.
• Attend all follow-up appointments so we can monitor how you are responding to treatment.