Drug interactions
Ethinyl estradiol-levonorgestrel + Ritonavir
Severity: Major
Ethinyl estradiol-levonorgestrel and Ritonavir: major interaction.
Last updated Sources: US FDA label
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 alters hormone exposure from combined contraceptives. It inhibits CYP3A4 but also induces other enzymes and glucuronidation, so ethinyl estradiol levels often fall and contraceptive efficacy may be reduced. Changes in progestin exposure and a possible increase in adverse effects are also described.
What this interaction means in plain words
Ethinyl estradiol-levonorgestrel and Ritonavir can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Ethinyl estradiol-levonorgestrel belongs to Endocrine; Ritonavir belongs to Anti Virals.
Why it happens
Mixed CYP3A4 inhibition and induction of glucuronidation and other enzymes by ritonavir changes the metabolism of both hormones.
What to do
Use an alternative or additional non-hormonal contraceptive method during ritonavir-containing therapy. Consider a different contraceptive if long-term protease inhibitor use is planned.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Ethinyl estradiol-levonorgestrel
- Ethinyl estradiol-levonorgestrel + Fezolinetant Contraindicated
- Ethinyl estradiol-levonorgestrel + Ombitasvir / paritaprevir / ritonavir and dasabuvir Contraindicated
- Ethinyl estradiol-levonorgestrel + Tranexamic acid Contraindicated
- Aminocaproic acid + Ethinyl estradiol-levonorgestrel Major
- Amobarbital + Ethinyl estradiol-levonorgestrel Major
- Anastrozole + Ethinyl estradiol-levonorgestrel 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 Ethinyl estradiol-levonorgestrel with Ritonavir?
MediHelp rates the interaction as major. Ethinyl estradiol-levonorgestrel and Ritonavir can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Ritonavir alters hormone exposure from combined contraceptives. It inhibits CYP3A4 but also induces other enzymes and glucuronidation, so ethinyl estradiol levels often fall and contraceptive efficacy may be reduced. Changes in progestin exposure and a possible increase in adverse effects are also described.
How serious is the interaction between Ethinyl estradiol-levonorgestrel and Ritonavir?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use an alternative or additional non-hormonal contraceptive method during ritonavir-containing therapy. Consider a different contraceptive if long-term protease inhibitor use is planned.
What other medicines interact with Ethinyl estradiol-levonorgestrel?
MediHelp also lists interactions of Ethinyl estradiol-levonorgestrel with, for example, Fezolinetant, Ombitasvir / paritaprevir / ritonavir and dasabuvir, Tranexamic acid. The full list is on the Ethinyl estradiol-levonorgestrel page.
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