Drug interactions
Levonorgestrel intrauterine + Phenytoin
Severity: Minor
Levonorgestrel intrauterine and Phenytoin: minor 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
Phenytoin lowers systemic levonorgestrel levels, but the intrauterine system acts mainly locally on the endometrium, so contraceptive efficacy is largely preserved. Systemic effects such as cycle control may be altered.
What this interaction means in plain words
Levonorgestrel intrauterine and Phenytoin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Phenytoin induces CYP3A4, increasing levonorgestrel metabolism.
What to do
No routine change is needed for the intrauterine system. Monitor bleeding pattern and consider additional contraception if concerns arise.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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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 Levonorgestrel intrauterine with Phenytoin?
MediHelp rates the interaction as minor. Levonorgestrel intrauterine and Phenytoin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Phenytoin lowers systemic levonorgestrel levels, but the intrauterine system acts mainly locally on the endometrium, so contraceptive efficacy is largely preserved. Systemic effects such as cycle control may be altered.
How serious is the interaction between Levonorgestrel intrauterine and Phenytoin?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine change is needed for the intrauterine system. Monitor bleeding pattern and consider additional contraception if concerns arise.
What other medicines interact with Phenytoin?
MediHelp also lists interactions of Phenytoin with, for example, Artemether / lumefantrine, Bictegravir, Cabotegravir. The full list is on the Phenytoin page.
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