Norethindrone (Jencycla, Movisse, Maeve)

1. Health Canada Product Monograph — Norethindrone

• Norethindrone 0.35 mg tablets are used for pregnancy prevention (birth control) in patients who cannot or prefer not to use estrogen-containing contraception.
• Works mainly by thickening cervical mucus to block sperm penetration; it inhibits ovulation in only about half of cycles, so consistent daily timing is essential to maintain contraceptive effect.

• Norethindrone should not be used during known or suspected pregnancy.
• If pregnancy occurs during use, evaluate for ectopic pregnancy, since progestin-only pills do not reliably suppress ovulation in every cycle.
• Epidemiologic studies have not found an increased risk of birth defects when progestin-only contraceptives are inadvertently used in early pregnancy.

• Progestin-only pills are considered compatible with breastfeeding and have not been shown to adversely affect milk supply, infant growth, or infant development.
• Can be started immediately postpartum, including in breastfeeding patients.

• Not indicated for use in postmenopausal patients.

• May be used in adolescents who have started menstruating and require contraception; not indicated before menarche.

• One tablet taken by mouth once daily, continuously, with no hormone-free interval; every pack contains 28 active tablets.
• Take at approximately the same time every day — the effect on cervical mucus declines within a few hours of the scheduled dose, so consistent timing matters more than with combined pills.
• If a dose is taken more than 3 hours late, or a dose is missed, take a tablet as soon as remembered, continue the rest of the pack on schedule, and use a backup (barrier) contraceptive method for the next 48 hours.
• Use a backup method for the first 48 hours after starting, unless starting within the first 5 days of the menstrual cycle.
• If vomiting or severe diarrhea occurs within a few hours of a dose, treat it the same as a missed dose and use backup contraception.

If overdose is suspected, seek emergency medical attention immediately or contact your regional Poison Control Centre without delay.

• Overdose may cause nausea, vomiting, or withdrawal-type vaginal bleeding.
• No specific antidote exists; treatment is supportive.

• Irregular or unscheduled bleeding and spotting, most common in the first several months of use.
• Headache.
• Breast tenderness.
• Nausea.
• Mood changes.
• Acne.
• Weight change.

Serious side effects require immediate discussion with the prescriber or emergency care.

• Consider ectopic pregnancy in anyone who becomes pregnant while using norethindrone or who develops new lower abdominal pain.
• Venous thromboembolism is a rare but reported risk; seek urgent care for leg swelling or pain, chest pain, sudden shortness of breath, severe headache, or vision changes.
• New or worsening depression.
• Liver problems, including jaundice.

• Use with caution in patients with a history of ectopic pregnancy.
• Use with caution in patients with active liver disease or a history of liver tumours.
• Counsel that missing the 3-hour dosing window is the most common cause of contraceptive failure with this specific product, more so than with drospirenone-only or combined pills.

• Known or suspected pregnancy.
• Current breast cancer.
• Active liver disease or liver tumour.
• Undiagnosed abnormal vaginal bleeding that has not yet been evaluated.

• Enzyme-inducing medications (carbamazepine, oxcarbazepine, eslicarbazepine, phenytoin, phenobarbital, primidone, rifampin, rifabutin, St. John's wort, topiramate) reduce norethindrone serum concentrations and contraceptive effectiveness; use backup contraception or select a non-oral method during concurrent use.
• GLP-1 receptor agonists with delayed gastric emptying (notably tirzepatide) may reduce absorption during dose escalation; use backup contraception for 4 weeks after initiation and after each dose increase, or select a non-oral method.

• No clinically significant food interactions have been identified.

• Taken once daily at the same time every day, continuously, with no scheduled break between packs.

• Store at room temperature (15°C to 30°C) in the original packaging.

• Norethindrone is a progestin-only (“mini”) pill taken every day at the same time, with no placebo week.
• Because the mucus-thickening effect wears off quickly, being more than 3 hours late counts as a missed dose — take it as soon as remembered and use backup contraception for 48 hours.
• Irregular bleeding is common, especially in the first few months, and usually improves with continued use.
• This pill does not protect against sexually transmitted infections — use condoms for that protection.
• Tell your pharmacist or prescriber about all other medications you take, since several common drugs can make this pill less effective.