Drug interactions
Ergocalciferol + Phenobarbital
Severity: Moderate
Ergocalciferol and Phenobarbital: 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 phenobarbital use increases vitamin D breakdown and can cause vitamin D deficiency, osteomalacia or reduced bone density. Standard supplement doses may be less effective.
What this interaction means in plain words
Ergocalciferol and Phenobarbital 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.
Why it happens
Phenobarbital induces hepatic CYP enzymes, accelerating the catabolism of vitamin D and its metabolites.
What to do
Monitor 25-hydroxyvitamin D, calcium and bone health in chronic users, and increase vitamin D dosing as needed.
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 Ergocalciferol
- Aluminum hydroxide + Ergocalciferol Moderate
- Calcium acetate + Ergocalciferol Moderate
- Calcium carbonate + Ergocalciferol Moderate
- Calcium chloride + Ergocalciferol Moderate
- Calcium citrate + Ergocalciferol Moderate
- Calcium gluconate + Ergocalciferol Moderate
Frequently asked questions
Can I take Ergocalciferol with Phenobarbital?
MediHelp rates the interaction as moderate. Ergocalciferol and Phenobarbital 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 phenobarbital use increases vitamin D breakdown and can cause vitamin D deficiency, osteomalacia or reduced bone density. Standard supplement doses may be less effective.
How serious is the interaction between Ergocalciferol and Phenobarbital?
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 chronic users, and increase vitamin D dosing as needed.
What other medicines interact with Ergocalciferol?
MediHelp also lists interactions of Ergocalciferol with, for example, Aluminum hydroxide, Calcium acetate, Calcium carbonate. The full list is on the Ergocalciferol page.
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