Drug interactions
Cholecalciferol + Phenytoin
Severity: Moderate
Cholecalciferol 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
Long-term phenytoin therapy increases vitamin D catabolism and can lower vitamin D status. This may contribute to osteomalacia, reduced bone density and low calcium in chronically treated patients.
What this interaction means in plain words
Cholecalciferol 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.
Cholecalciferol belongs to Musculoskeletal; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces hepatic CYP enzymes, accelerating metabolism of vitamin D and its metabolites to inactive forms.
What to do
Monitor 25-hydroxyvitamin D, calcium and bone health in long-term users. Give vitamin D supplementation and increase the dose if levels remain low.
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 Cholecalciferol
- Cholecalciferol + Digoxin Major
- Aluminum hydroxide + Cholecalciferol Moderate
- Calcium acetate + Cholecalciferol Moderate
- Calcium Carbonate + Cholecalciferol Moderate
- Calcium chloride + Cholecalciferol Moderate
- Calcium citrate + Cholecalciferol 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 Cholecalciferol with Phenytoin?
MediHelp rates the interaction as moderate. Cholecalciferol 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. Long-term phenytoin therapy increases vitamin D catabolism and can lower vitamin D status. This may contribute to osteomalacia, reduced bone density and low calcium in chronically treated patients.
How serious is the interaction between Cholecalciferol 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 25-hydroxyvitamin D, calcium and bone health in long-term users. Give vitamin D supplementation and increase the dose if levels remain low.
What other medicines interact with Cholecalciferol?
MediHelp also lists interactions of Cholecalciferol with, for example, Digoxin, Aluminum hydroxide, Calcium acetate. The full list is on the Cholecalciferol page.
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