Drug interactions
Furosemide + Phenytoin
Severity: Moderate
Furosemide 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
Oral phenytoin has been reported to lower the absorption and diuretic effect of oral furosemide. The result can be a weaker natriuretic response in patients who depend on the diuretic for edema control.
What this interaction means in plain words
Furosemide 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.
Furosemide belongs to Cardiovascular; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin appears to reduce gastrointestinal absorption of furosemide; the exact mechanism is not fully established.
What to do
Watch for reduced diuretic response and increase the furosemide dose or use an intravenous route if needed. Monitor weight and edema.
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 Furosemide
- Amifostine + Furosemide Major
- Amikacin + Furosemide Major
- Carbenoxolone + Furosemide Major
- Cephaloridine + Furosemide Major
- Cisplatin + Furosemide Major
- Digoxin + Furosemide Major
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 Furosemide with Phenytoin?
MediHelp rates the interaction as moderate. Furosemide 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. Oral phenytoin has been reported to lower the absorption and diuretic effect of oral furosemide. The result can be a weaker natriuretic response in patients who depend on the diuretic for edema control.
How serious is the interaction between Furosemide 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: Watch for reduced diuretic response and increase the furosemide dose or use an intravenous route if needed. Monitor weight and edema.
What other medicines interact with Furosemide?
MediHelp also lists interactions of Furosemide with, for example, Amifostine, Amikacin, Carbenoxolone. The full list is on the Furosemide page.
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