Drug interactions
Mifepristone + Norethisterone
Severity: Moderate
Mifepristone and Norethisterone: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Mifepristone antagonizes progesterone receptors, which can counteract the progestin effect of norethisterone, and inhibits CYP3A4, which may alter norethisterone exposure. Contraceptive and endometrial protective effects may be unreliable.
What this interaction means in plain words
Mifepristone and Norethisterone can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Mifepristone belongs to Endocrine; Norethisterone belongs to Endocrine.
Why it happens
Progesterone receptor antagonism by mifepristone with CYP3A4 inhibition.
What to do
Do not depend on norethisterone for contraception during mifepristone treatment; use a non-hormonal method. Reassess the indication for the progestin.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Norethisterone
- Acitretin + Norethisterone Contraindicated
- Amobarbital + Norethisterone Major
- Apalutamide + Norethisterone Major
- Belzutifan + Norethisterone Major
- Bosentan + Norethisterone Major
- Brigatinib + Norethisterone Major
Other interactions of Mifepristone
- Apixaban + Mifepristone Contraindicated
- Argatroban + Mifepristone Contraindicated
- Cisapride + Mifepristone Contraindicated
- Cortisone + Mifepristone Contraindicated
- Cyclosporin + Mifepristone Contraindicated
- Dabigatran etexilate + Mifepristone Contraindicated
Frequently asked questions
Can I take Mifepristone with Norethisterone?
MediHelp rates the interaction as moderate. Mifepristone and Norethisterone can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Mifepristone antagonizes progesterone receptors, which can counteract the progestin effect of norethisterone, and inhibits CYP3A4, which may alter norethisterone exposure. Contraceptive and endometrial protective effects may be unreliable.
How serious is the interaction between Mifepristone and Norethisterone?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Do not depend on norethisterone for contraception during mifepristone treatment; use a non-hormonal method. Reassess the indication for the progestin.
What other medicines interact with Norethisterone?
MediHelp also lists interactions of Norethisterone with, for example, Acitretin, Amobarbital, Apalutamide. The full list is on the Norethisterone page.
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