Drug interactions
Dapsone + Phenytoin
Severity: Moderate
Dapsone and Phenytoin: moderate 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 including CYP3A4 and may lower dapsone levels, possibly reducing efficacy. Enzyme induction may also increase formation of the hydroxylamine metabolite responsible for hemolysis and methemoglobinemia.
What this interaction means in plain words
Dapsone and Phenytoin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Dapsone belongs to Anti Bacterial; Phenytoin belongs to Central Nervous System.
Why it happens
Enzyme induction by phenytoin increases dapsone metabolism and may increase toxic hydroxylamine formation.
What to do
Monitor clinical response to dapsone and check hemoglobin and methemoglobin if symptoms occur. Adjust dapsone dose based on response and tolerance.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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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 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 Dapsone with Phenytoin?
MediHelp rates the interaction as moderate. Dapsone and Phenytoin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Phenytoin induces hepatic enzymes including CYP3A4 and may lower dapsone levels, possibly reducing efficacy. Enzyme induction may also increase formation of the hydroxylamine metabolite responsible for hemolysis and methemoglobinemia.
How serious is the interaction between Dapsone and Phenytoin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor clinical response to dapsone and check hemoglobin and methemoglobin if symptoms occur. Adjust dapsone dose based on response and tolerance.
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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