Drug interactions
Calcifediol + Isoniazid
Severity: Moderate
Calcifediol and Isoniazid: 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
Isoniazid interferes with vitamin D hydroxylation and can reduce activation of vitamin D metabolites, potentially lowering calcitriol formation. This may alter calcium and PTH control in patients taking calcifediol.
What this interaction means in plain words
Calcifediol and Isoniazid 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.
Calcifediol belongs to Musculoskeletal; Isoniazid belongs to Anti Bacterial.
Why it happens
Isoniazid inhibits hepatic and renal vitamin D hydroxylating and metabolizing enzymes, altering conversion of calcifediol.
What to do
Monitor serum 25-hydroxyvitamin D, PTH and calcium when starting or stopping isoniazid, and adjust the calcifediol dose accordingly.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Calcifediol and Isoniazid, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
Other interactions of Isoniazid
Other interactions of Calcifediol
- Amlodipine-hydrochlorothiazide-valsartan + Calcifediol Moderate
- Amlodipine-olmesartan-hydrochlorothiazide + Calcifediol Moderate
- Amobarbital + Calcifediol Moderate
- Atenolol-chlorthalidone + Calcifediol Moderate
- Azilsartan-chlorthalidone + Calcifediol Moderate
- Calcifediol + Candesartan-hydrochlorothiazide Moderate
Frequently asked questions
Can I take Calcifediol with Isoniazid?
MediHelp rates the interaction as moderate. Calcifediol and Isoniazid 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. Isoniazid interferes with vitamin D hydroxylation and can reduce activation of vitamin D metabolites, potentially lowering calcitriol formation. This may alter calcium and PTH control in patients taking calcifediol.
How serious is the interaction between Calcifediol and Isoniazid?
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 serum 25-hydroxyvitamin D, PTH and calcium when starting or stopping isoniazid, and adjust the calcifediol dose accordingly.
What other medicines interact with Isoniazid?
MediHelp also lists interactions of Isoniazid with, for example, Bacillus calmette-guerin substrain tice, Benzhydrocodone / acetaminophen, Carbamazepine. The full list is on the Isoniazid page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
