Drug interactions
Fosphenytoin + Ivermectin
Severity: Minor
Fosphenytoin and Ivermectin: 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
Fosphenytoin, through its active metabolite phenytoin, induces CYP3A4 and P-glycoprotein and may lower ivermectin concentrations. Reduced exposure could lessen antiparasitic efficacy, though clinical data are lacking.
What this interaction means in plain words
Fosphenytoin and Ivermectin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Fosphenytoin belongs to Central Nervous System; Ivermectin belongs to Anti Parasitic.
Why it happens
Phenytoin induces CYP3A4 and P-glycoprotein, increasing ivermectin clearance and reducing absorption.
What to do
No empiric dose change is needed. Check for treatment response and re-treat if parasitological or clinical cure is not achieved.
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 Ivermectin
- Erdafitinib + Ivermectin Moderate
- Ivermectin + Lasmiditan Moderate
- Ivermectin + Quinidine Moderate
- Ivermectin + Rifampin Moderate
- Ivermectin + Sotorasib Moderate
- Ivermectin + Tepotinib Moderate
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 Ivermectin?
MediHelp rates the interaction as minor. Fosphenytoin and Ivermectin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Fosphenytoin, through its active metabolite phenytoin, induces CYP3A4 and P-glycoprotein and may lower ivermectin concentrations. Reduced exposure could lessen antiparasitic efficacy, though clinical data are lacking.
How serious is the interaction between Fosphenytoin and Ivermectin?
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 empiric dose change is needed. Check for treatment response and re-treat if parasitological or clinical cure is not achieved.
What other medicines interact with Ivermectin?
MediHelp also lists interactions of Ivermectin with, for example, Erdafitinib, Lasmiditan, Quinidine. The full list is on the Ivermectin page.
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