Drug interactions
Fosphenytoin + Praziquantel
Severity: Major
Fosphenytoin and Praziquantel: 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 lowers praziquantel concentrations substantially and can lead to treatment failure. Antiparasitic efficacy may be lost.
What this interaction means in plain words
Fosphenytoin and Praziquantel 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.
Fosphenytoin belongs to Central Nervous System; Praziquantel belongs to Anti Parasitic.
Why it happens
Phenytoin induces CYP3A4 and other enzymes, accelerating praziquantel metabolism.
What to do
Avoid if possible by using a non-inducing anticonvulsant during treatment; otherwise monitor response and consider dose adjustment or retreatment.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Fosphenytoin and Praziquantel, 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.
References
Other interactions of Praziquantel
- Enzalutamide + Praziquantel Contraindicated
- Praziquantel + Rifampin Contraindicated
- Amobarbital + Praziquantel Major
- Apalutamide + Praziquantel Major
- Butabarbital + Praziquantel Major
- Butalbital + Praziquantel Major
Other interactions of Fosphenytoin
- Dronedarone + Fosphenytoin Contraindicated
- Fosphenytoin + Ledipasvir-sofosbuvir Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
- Fosphenytoin + Lurasidone Contraindicated
- Fosphenytoin + Ranolazine Contraindicated
- Fosphenytoin + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
Frequently asked questions
Can I take Fosphenytoin with Praziquantel?
MediHelp rates the interaction as major. Fosphenytoin and Praziquantel 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 lowers praziquantel concentrations substantially and can lead to treatment failure. Antiparasitic efficacy may be lost.
How serious is the interaction between Fosphenytoin and Praziquantel?
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 if possible by using a non-inducing anticonvulsant during treatment; otherwise monitor response and consider dose adjustment or retreatment.
What other medicines interact with Praziquantel?
MediHelp also lists interactions of Praziquantel with, for example, Enzalutamide, Rifampin, Amobarbital. The full list is on the Praziquantel 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.
