Drug interactions
Dapsone + Fosphenytoin
Severity: Minor
Dapsone and Fosphenytoin: 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, via phenytoin, induces CYP3A4 and may lower dapsone concentrations. Reduced efficacy is possible with sustained use.
What this interaction means in plain words
Dapsone and Fosphenytoin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Dapsone belongs to Anti Bacterial; Fosphenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4 and other hepatic enzymes, accelerating dapsone metabolism.
What to do
Monitor for loss of dapsone effect and adjust the dose if needed. Watch for dapsone-related hematologic effects if the anticonvulsant is stopped.
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 Dapsone
- Bcg vaccine live + Dapsone Major
- Dapsone + Primaquine Major
- Apalutamide + Dapsone Moderate
- Belzutifan + Dapsone Moderate
- Bosentan + Dapsone Moderate
- Bupivacaine implant + Dapsone 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 Dapsone with Fosphenytoin?
MediHelp rates the interaction as minor. Dapsone and Fosphenytoin 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, via phenytoin, induces CYP3A4 and may lower dapsone concentrations. Reduced efficacy is possible with sustained use.
How serious is the interaction between Dapsone and Fosphenytoin?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for loss of dapsone effect and adjust the dose if needed. Watch for dapsone-related hematologic effects if the anticonvulsant is stopped.
What other medicines interact with Dapsone?
MediHelp also lists interactions of Dapsone with, for example, Bcg vaccine live, Primaquine, Apalutamide. The full list is on the Dapsone page.
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