Understanding Safety: What medications should not be taken with vitamin D?

October 11, 2025 •

3 min read

According to a 2025 article, approximately one-third of Americans take a vitamin D supplement, highlighting its widespread use. However, what many people don't realize is that this popular supplement can interact with several common medications, potentially leading to serious health risks. Understanding what medications should not be taken with vitamin D is crucial for ensuring your treatment remains both safe and effective.

Quick Summary

Vitamin D supplements can interact with various medications, altering drug effectiveness or causing adverse effects like high blood calcium. Specific drugs, including certain diuretics, statins, antiseizure medications, and cardiac glycosides, require careful monitoring or dose adjustments to manage these interactions safely.

Key Points

Thiazide Diuretics: These blood pressure medications increase calcium retention, so combining them with vitamin D can cause dangerously high blood calcium levels (hypercalcemia).
Cardiac Glycosides: High vitamin D doses increase calcium absorption, which heightens the risk of toxicity from heart rhythm medications like digoxin.
Anticonvulsants: Certain seizure medications, such as phenytoin, can speed up the breakdown of vitamin D in the body, potentially leading to vitamin D deficiency and weaker bones over time.
Cholesterol Drugs: Bile acid sequestrants, like cholestyramine, prevent the gut from absorbing fat-soluble vitamins, including vitamin D, and should be taken separately.
Corticosteroids: Long-term use of anti-inflammatory steroids, such as prednisone, can interfere with vitamin D's function and calcium absorption, increasing the risk of bone loss.
Weight-Loss Drugs: The lipase inhibitor orlistat works by blocking fat absorption, which also hinders the absorption of fat-soluble vitamin D and requires timed supplementation.
Consult a Professional: Always talk to a doctor or pharmacist about all supplements and medications you take to check for potential interactions and monitor health markers.

Medications That Increase Blood Calcium Levels

Taking vitamin D with certain medications can lead to hypercalcemia (high blood calcium), which can cause symptoms like nausea, confusion, kidney stones, and heart rhythm issues.

Thiazide Diuretics

Thiazide diuretics, used for high blood pressure, decrease calcium excretion. Combining them with vitamin D can dangerously increase calcium levels. Examples include hydrochlorothiazide and chlorthalidone. Blood calcium should be monitored in patients taking both.

Cardiac Glycosides

Digoxin, used for heart conditions, can cause toxicity if calcium levels are high. Vitamin D can increase calcium absorption, raising this risk. Those taking digoxin need close calcium level monitoring.

Calcipotriene

This topical psoriasis medication is a synthetic vitamin D and should not be used with oral vitamin D supplements due to the risk of hypercalcemia.

Medications That Interfere with Vitamin D Absorption

Some medications can hinder vitamin D absorption or use.

Bile Acid Sequestrants

Cholesterol drugs like cholestyramine can bind to and reduce the absorption of fat-soluble vitamin D. Taking vitamin D at a different time, one to four hours apart, is recommended.

Lipase Inhibitors

Orlistat, a weight-loss drug, blocks fat absorption and thus reduces vitamin D absorption. A multivitamin with fat-soluble vitamins, taken at a different time than orlistat, is often advised.

Mineral Oil

Long-term use of mineral oil can interfere with the absorption of fat-soluble vitamins, including vitamin D. Timing vitamin D supplementation separately is important.

Corticosteroids

Systemic corticosteroids like prednisone can impair calcium absorption and vitamin D metabolism, increasing bone loss risk. Supplementation may be recommended under medical supervision.

Medications That Accelerate Vitamin D Metabolism

Certain drugs increase the breakdown of vitamin D in the body.

Anticonvulsants

Antiseizure medications such as phenytoin and phenobarbital can lower vitamin D levels, potentially affecting bone density. Higher doses of vitamin D may be needed for patients on these drugs.

Interactions with Cholesterol-Lowering Drugs

While the interaction between statins and vitamin D is not fully clear, some statins may compete with vitamin D for metabolism. Close monitoring of cholesterol levels is advised if taking both.

Comparison of Key Vitamin D Interactions


Drug Class	Example Medications	Mechanism of Interaction	Potential Risk
Thiazide Diuretics	Hydrochlorothiazide, Chlorthalidone	Reduces calcium excretion, adds to vitamin D's effect of increasing calcium absorption.	Hypercalcemia (high blood calcium).
Cardiac Glycosides	Digoxin (Lanoxin)	High vitamin D doses increase calcium, raising risk of toxicity.	Digoxin toxicity, irregular heartbeats.
Anticonvulsants	Phenytoin, Phenobarbital	Increases breakdown of vitamin D in the liver, leading to lower levels.	Vitamin D deficiency, bone density loss.
Bile Acid Sequestrants	Cholestyramine (Prevalite)	Binds to vitamin D in the gut, preventing absorption.	Reduced vitamin D absorption and effectiveness.
Lipase Inhibitors	Orlistat (Xenical, Alli)	Blocks absorption of dietary fat, hindering vitamin D absorption.	Reduced absorption of vitamin D.
Systemic Corticosteroids	Prednisone, Hydrocortisone	Impairs calcium absorption and vitamin D metabolism.	Weakened bones, osteoporosis risk.
Statins	Atorvastatin, Lovastatin	Potential competition for the same liver enzyme, affecting metabolism.	Reduced statin effectiveness (needs further research).

Conclusion

Discussing all medications and supplements with your healthcare provider is crucial for safety. Vitamin D can interact with drugs like diuretics, cardiac glycosides, and anticonvulsants. Never stop prescribed medication without consulting a doctor. Staying informed about potential interactions helps ensure safe use of both medications and supplements. For more information, the National Institutes of Health Office of Dietary Supplements provides fact sheets. National Institutes of Health Office of Dietary Supplements.

Potential Symptoms of Hypercalcemia

Symptoms of high calcium levels can include nausea, fatigue, confusion, muscle weakness, frequent urination, kidney stones, and irregular heart rhythms. Seek medical attention if you experience these symptoms while taking vitamin D and other medications.

Frequently Asked Questions

If you are on a thiazide diuretic (e.g., hydrochlorothiazide), combining it with vitamin D raises your risk of hypercalcemia. Other classes of blood pressure medication, like ACE inhibitors, are generally considered safer to take with vitamin D.

Some research suggests that certain statins and high-dose vitamin D supplements could compete for a common metabolic pathway, potentially affecting the statin's effectiveness. Always inform your doctor if you take both, so they can monitor your cholesterol levels closely.

Hypercalcemia is a condition of having too much calcium in the blood. When combined with cardiac glycosides like digoxin, the increased calcium levels can trigger serious heart rhythm problems, and with diuretics, it can cause symptoms like nausea, confusion, and kidney stones.

If you take a medication like orlistat or cholestyramine that impairs absorption, your doctor may advise you to take your vitamin D supplement at a different time of day, often separated by several hours.

Since certain antiseizure drugs cause the body to break down vitamin D more quickly, they can lead to deficiency and weakened bones. Your healthcare provider may recommend a higher dose of vitamin D and monitor your levels.

Yes, specific calcium supplements, especially when combined with medications like thiazide diuretics, can lead to excessively high calcium levels. Furthermore, the topical psoriasis treatment calcipotriene is a synthetic vitamin D and should not be combined with oral vitamin D.

No, you should never stop taking a prescribed medication without first consulting your doctor. They can provide guidance on how to safely manage any necessary vitamin D supplementation, potentially by adjusting dosages or monitoring blood levels.