Drug interactions
Norethisterone + Ritonavir
Severity: Moderate
Norethisterone and Ritonavir: 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
Ritonavir inhibits CYP3A4 but also induces other metabolic pathways, so norethisterone and ethinylestradiol exposure may be altered unpredictably. Contraceptive reliability may be reduced and adverse effects may increase.
What this interaction means in plain words
Norethisterone and Ritonavir 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.
Norethisterone belongs to Endocrine; Ritonavir belongs to Anti Virals.
Why it happens
Ritonavir inhibits CYP3A4 and induces glucuronidation and some CYP enzymes, producing variable effects on norethisterone clearance.
What to do
Use an additional or alternative non-hormonal contraceptive method and monitor for adverse effects or breakthrough bleeding.
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 Ritonavir
- Alfuzosin + Ritonavir Contraindicated
- Amiodarone + Ritonavir Contraindicated
- Avanafil + Ritonavir Contraindicated
- Colchicine + Ritonavir Contraindicated
- Dronedarone + Ritonavir Contraindicated
- Eletriptan + Ritonavir Contraindicated
Frequently asked questions
Can I take Norethisterone with Ritonavir?
MediHelp rates the interaction as moderate. Norethisterone and Ritonavir 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. Ritonavir inhibits CYP3A4 but also induces other metabolic pathways, so norethisterone and ethinylestradiol exposure may be altered unpredictably. Contraceptive reliability may be reduced and adverse effects may increase.
How serious is the interaction between Norethisterone and Ritonavir?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use an additional or alternative non-hormonal contraceptive method and monitor for adverse effects or breakthrough bleeding.
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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