Drug interactions
Phenytoin + Thalidomide
Severity: Major
Phenytoin and Thalidomide: major 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 induces hepatic enzymes and can reduce hormonal contraceptive levels, leading to contraceptive failure. This is a particular concern with thalidomide because of its serious teratogenicity.
What this interaction means in plain words
Phenytoin and Thalidomide 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 belongs to Central Nervous System; Thalidomide belongs to Miscellaneous.
Why it happens
Induction of CYP3A4 by phenytoin increases clearance of contraceptive hormones.
What to do
Avoid relying on hormonal contraception alone; use an IUD or other non-hormonal highly effective method plus a barrier method while on phenytoin.
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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Other interactions of Thalidomide
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 Phenytoin with Thalidomide?
MediHelp rates the interaction as major. Phenytoin and Thalidomide 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 induces hepatic enzymes and can reduce hormonal contraceptive levels, leading to contraceptive failure. This is a particular concern with thalidomide because of its serious teratogenicity.
How serious is the interaction between Phenytoin and Thalidomide?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid relying on hormonal contraception alone; use an IUD or other non-hormonal highly effective method plus a barrier method while on phenytoin.
What other medicines interact with Thalidomide?
MediHelp also lists interactions of Thalidomide with, for example, Bortezomib, Carbamazepine, Griseofulvin. The full list is on the Thalidomide page.
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