Drug interactions
Ethinyl estradiol-levonorgestrel + Phenytoin
Severity: Major
Ethinyl estradiol-levonorgestrel and Phenytoin: 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
Phenytoin is an enzyme inducer that substantially lowers contraceptive hormone levels and has been linked to contraceptive failure and breakthrough bleeding. Women exposed to phenytoin in pregnancy face fetal risk, so reliable contraception is important.
What this interaction means in plain words
Ethinyl estradiol-levonorgestrel and Phenytoin 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; Phenytoin belongs to Central Nervous System.
Why it happens
Induction of CYP3A4 and other hepatic enzymes increases the clearance of ethinyl estradiol and levonorgestrel.
What to do
Prefer non-hormonal contraception such as a copper IUD or a levonorgestrel IUD, or injectable medroxyprogesterone. Avoid relying on combined oral contraceptives.
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 Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Frequently asked questions
Can I take Ethinyl estradiol-levonorgestrel with Phenytoin?
MediHelp rates the interaction as major. Ethinyl estradiol-levonorgestrel and Phenytoin 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. Phenytoin is an enzyme inducer that substantially lowers contraceptive hormone levels and has been linked to contraceptive failure and breakthrough bleeding. Women exposed to phenytoin in pregnancy face fetal risk, so reliable contraception is important.
How serious is the interaction between Ethinyl estradiol-levonorgestrel and Phenytoin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Prefer non-hormonal contraception such as a copper IUD or a levonorgestrel IUD, or injectable medroxyprogesterone. Avoid relying on combined oral contraceptives.
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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