Drug interactions
Ethinyl estradiol-norgestimate + Nirmatrelvir / ritonavir
Severity: Moderate
Ethinyl estradiol-norgestimate and Nirmatrelvir / 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-boosted nirmatrelvir may lower ethinyl estradiol exposure and thus contraceptive efficacy. The short course limits the risk, but unintended pregnancy is possible.
What this interaction means in plain words
Ethinyl estradiol-norgestimate and Nirmatrelvir / 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.
Why it happens
Ritonavir may induce enzymes that metabolize ethinyl estradiol, including CYP1A2, CYP2C9 and glucuronidation.
What to do
Use an additional non-hormonal contraceptive method for the rest of the cycle after the course.
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 Ethinyl estradiol-norgestimate and Nirmatrelvir / ritonavir, 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 7 days on the web. No card needed.
Other interactions of Ethinyl estradiol-norgestimate
- Ethinyl estradiol-norgestimate + Fezolinetant Contraindicated
- Ethinyl estradiol-norgestimate + Ombitasvir / paritaprevir / ritonavir and dasabuvir Contraindicated
- Ethinyl estradiol-norgestimate + Tranexamic acid Contraindicated
- Aminocaproic acid + Ethinyl estradiol-norgestimate Major
- Amobarbital + Ethinyl estradiol-norgestimate Major
- Anastrozole + Ethinyl estradiol-norgestimate Major
Frequently asked questions
Can I take Ethinyl estradiol-norgestimate with Nirmatrelvir / ritonavir?
MediHelp rates the interaction as moderate. Ethinyl estradiol-norgestimate and Nirmatrelvir / 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-boosted nirmatrelvir may lower ethinyl estradiol exposure and thus contraceptive efficacy. The short course limits the risk, but unintended pregnancy is possible.
How serious is the interaction between Ethinyl estradiol-norgestimate and Nirmatrelvir / 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 non-hormonal contraceptive method for the rest of the cycle after the course.
What other medicines interact with Ethinyl estradiol-norgestimate?
MediHelp also lists interactions of Ethinyl estradiol-norgestimate with, for example, Fezolinetant, Ombitasvir / paritaprevir / ritonavir and dasabuvir, Tranexamic acid. The full list is on the Ethinyl estradiol-norgestimate 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.
