Using Primolut N (Norethisterone) for Breakthrough Bleeding While Traveling
Yes, Primolut N (norethisterone) can be used once daily to stop breakthrough bleeding, but you need to understand that it contains a progestogen that partially converts to ethinylestradiol (equivalent to 20-30 µg of estrogen from a 10-20 mg dose), which carries specific risks you should consider before use. 1
Effectiveness for Breakthrough Bleeding
Adding 5 mg norethisterone acetate (Primolut N) to progesterone-only contraceptives significantly reduces breakthrough bleeding frequency after 2,4, and 6 weeks of use, with the most pronounced effects on the endometrium making it highly effective for controlling abnormal bleeding. 2, 1
The typical dose that showed effectiveness in clinical studies was 5 mg norethisterone acetate, which demonstrated significant reduction in both bleeding frequency and quantity compared to other management strategies. 2
Safety Considerations You Must Know
Cardiovascular and Thrombotic Risks
Norethisterone at therapeutic doses (not contraceptive doses) may be associated with a moderately increased risk of venous thromboembolism due to its conversion to ethinylestradiol, and this risk appears dose-dependent. 1
If you have migraine with aura, you should avoid norethisterone because combinations of ethinylestradiol and progestogens are associated with increased ischemic stroke risk, particularly in women with migraine. 1
Avoid use if you have active thrombosis risk factors, history of blood clots, severe uncontrolled hypertension, or complicated valvular heart disease. 3
Other Important Contraindications
Do not use if you could be pregnant - rule this out first. 4
Avoid if you have ongoing liver dysfunction or hepatic disease. 3
Long-term use is associated with slightly increased breast cancer risk, though short-term use for breakthrough bleeding carries minimal concern. 1
Expected Timeline and Dosing
Most women experience significant improvement in breakthrough bleeding within 2 weeks of starting 5 mg norethisterone acetate daily, with continued improvement through 4-6 weeks. 2
The standard regimen studied was 5 mg daily, typically taken for 5 days when breakthrough bleeding occurs, though longer courses may be used depending on response. 5, 2
Common Side Effects to Expect
Menstrual irregularity is the most frequently reported side effect with norethisterone use. 6
Headache, breast tenderness, nausea, and dizziness may occur. 6
Less common effects include fatigue, edema, abdominal pain, and mood changes. 6
Critical Clinical Pearls
If you're already on progesterone-only contraception and experiencing breakthrough bleeding, adding norethisterone is more effective than doubling your contraceptive dose or switching to a different progesterone-only formulation. 2
The bleeding control effects are due to norethisterone's pronounced endometrial effects combined with its partial conversion to estrogen. 1
Once-daily dosing is appropriate and matches the studied regimen that demonstrated efficacy. 2
When NOT to Use This Approach
If bleeding is new-onset after prolonged amenorrhea, you need evaluation for pregnancy, sexually transmitted infections, or uterine pathology before treatment. 5
If you're over 75 years old with history of stroke or transient ischemic attack. 1
If you have known thrombophilia or are currently on anticoagulation therapy. 7