Drug interactions
Nelfinavir + Norethisterone
Severity: Moderate
Nelfinavir 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
Nelfinavir inhibits CYP3A4 but also lowers ethinylestradiol and norethisterone exposure in studies of oral contraceptives, so contraceptive efficacy may be affected.
What this interaction means in plain words
Nelfinavir 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.
Nelfinavir belongs to Anti Virals; Norethisterone belongs to Endocrine.
Why it happens
Nelfinavir has mixed effects, with CYP3A4 inhibition and induction of other hormone-metabolizing pathways such as glucuronidation, giving variable effects on norethisterone clearance.
What to do
Recommend an additional or alternative non-hormonal contraceptive method and monitor for 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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Nelfinavir and Norethisterone, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
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 Nelfinavir
- Alfuzosin + Nelfinavir Contraindicated
- Avanafil + Nelfinavir Contraindicated
- Dronedarone + Nelfinavir Contraindicated
- Eletriptan + Nelfinavir Contraindicated
- Ergotamine + Nelfinavir Contraindicated
- Flibanserin + Nelfinavir Contraindicated
Frequently asked questions
Can I take Nelfinavir with Norethisterone?
MediHelp rates the interaction as moderate. Nelfinavir 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. Nelfinavir inhibits CYP3A4 but also lowers ethinylestradiol and norethisterone exposure in studies of oral contraceptives, so contraceptive efficacy may be affected.
How serious is the interaction between Nelfinavir 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: Recommend an additional or alternative non-hormonal contraceptive method and monitor for 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.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
