Written by Rosanna Sutherby, PharmD | Reviewed by Stacia Woodcock, PharmD

Published on September 16, 2024print_outlinedemail_outlined

Key takeaways:

• Vitamin D is crucial for maintaining bone health and other essential functions. If you have low vitamin D levels, you may need a supplement such as vitamin D2 (ergocalciferol) or vitamin D3 (cholecalciferol).
• Vitamin D supplements can interact with other medications. Examples of vitamin D interactions include atorvastatin (Lipitor), cholestyramine (Prevalite) and phenytoin (Dilantin, Phenytek). Other Vitamin D drug interactions include orlistat (Xenical, Alli), digoxin (Lanoxin), and hydrochlorothiazide (Microzide).
• In most cases, you won’t need to stop taking one of your medications because of a vitamin D interaction. But tell your prescriber your full medication regimen before starting vitamin D. This will help them check for interactions.

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Table of contents

Statins

Bile acid sequestrants

Antibiotics

Seizure medications

Orlistat

Digoxin

Diuretics

FAQs

Bottom line

References

GoodRx Health

Vitamin D plays a significant role in maintaining healthy bones. It also helps regulate your muscular, nervous, and immune systems.

Your body makes vitamin D when you’re exposed to sunlight. You also get vitamin D from foods such as fatty fish, mushrooms, and vitamin D-fortified milk or cereal. Most people get enough vitamin D, but your healthcare team may check your levels if you’re at high risk for vitamin D deficiency. If your vitamin D levels are low, they may recommend a vitamin D supplement. Examples include vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). These supplements are available over the counter (OTC). But some forms and doses of vitamin D are available only by prescription.

Not getting enough vitamin D can lead to vitamin D deficiency. This can cause several health issues, including osteoporosis (weakened bones). So vitamin D supplements may be important to your overall health. But some medications interact with vitamin D. This increases your risk of side effects.

EXPERT PICKS: WHAT TO READ NEXT

• What’s the correct vitamin D supplement dose? Not everyone needs a vitamin D supplement. But if you do, taking the right dose is important.
• What causes Vitamin D deficiency and how do you treat it? There are several causes for vitamin D deficiency, and a few treatment options too.
• Can you get vitamin D through foods? Yes, and here are some of the best sources.

Here, we’ll cover seven vitamin D drug interactions and how to prevent or manage them.

1. Some statins, such as atorvastatin

Statins are a group of medications that lower cholesterol levels. Some statins are metabolized (broken down) by an enzyme (protein) in your liver called cytochrome P450 3A4 (CYP3A4).

Vitamin D can make CYP3A4 more active. Because of this, vitamin D may decrease blood levels of certain statins that are metabolized by this enzyme. This can make your statin less effective. Examples of statins that may be affected include:

• Atorvastatin (Lipitor)
• Lovastatin (Altoprev)
• Simvastatin (Zocor)

It’s important to note that although an interaction is possible, this doesn’t mean you can’t take vitamin D and a statin together. And it’s not clear how significant this reaction is, even if it does occur. Tell your prescriber if you’re taking one of these statins along with vitamin D supplements. They may want to monitor your cholesterol levels more closely. If needed, they may recommend switching to a statin that isn’t metabolized by CYP3A4, such as rosuvastatin (Crestor).

2. Bile acid sequestrants, such as cholestyramine

Another group of cholesterol medications is called bile acid sequestrants. These can also interact with vitamin D. One example of a bile acid sequestrant is cholestyramine (Prevalite).

These medications bind to fat-soluble vitamins like vitamin D in the intestines. This may reduce the amount of vitamin D your body can absorb. So if you’re taking a bile acid sequestrant with vitamin D, tell your prescriber. They may recommend separating your vitamin D supplement from your bile acid sequestrant. For example, some experts recommend taking vitamin D at least 1 hour before or 4 hours after your cholestyramine dose.

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Alternatively, your prescriber may recommend taking vitamin D once weekly. This dose is available by prescription only. With a once-weekly dosage, you’ll have to space your vitamin D medication from your bile acid sequestrant only 1 day a week (instead of daily).

3. Some antibiotics, such as rifampin and isoniazid

Rifampin (Rimactane) and isoniazid are antibiotics that treat tuberculosis. Rifampin increases CYP3A4 activity, while isoniazid blocks CYP3A4.

Vitamin D can make CYP3A4 more active. But CYP3A4 also helps convert vitamin D to a form that the body can use. So rifampin and isoniazid, which may be used alone or together, can affect how vitamin D supplements are metabolized.

If you take medication to treat tuberculosis, tell your healthcare team if you also take vitamin D supplements. They can monitor your vitamin D levels and recommend vitamin D dosage adjustments if needed.

4. Some seizure medications, such as phenytoin

Some seizure medications, including phenobarbital, phenytoin (Dilantin, Phenytek), and carbamazepine (Tegretol), can decrease vitamin D levels. They do this by speeding up the breakdown of vitamin D in the body. This is why vitamin D supplements may be recommended for people who take certain seizure medications.

But seizure medications can also speed up how quickly vitamin D supplements are broken down. So you may need a higher dose of your vitamin D supplement if you’re taking a seizure medication. Ask a healthcare professional what dosage of vitamin D is best for you.

5. Orlistat

Orlistat (Xenical) is a prescription medication used to help with weight loss. It’s also available OTC without a prescription (Alli).

Orlistat works by blocking your body from absorbing fat in food. And because vitamin D is a fat-soluble vitamin, orlistat can decrease absorption of this vitamin.

If you take orlistat, taking a vitamin D supplement may be recommended. In fact, it’s often recommended to take a multivitamin containing all fat-soluble vitamins (vitamin A, D, E, and K) while you’re taking orlistat. It’s best to take vitamin D at bedtime or at least 2 hours apart from an Orlistat dose.

6. Digoxin

Digoxin (Lanoxin) is a medication that treats conditions like heart failure and atrial fibrillation (an abnormal heart rhythm).

Taking digoxin with regular doses of vitamin D supplements doesn’t usually cause a vitamin D drug interaction. But high doses of vitamin D may increase your blood calcium levels. Having high calcium levels while taking digoxin increases your risk for digoxin toxicity. This can lead to nausea and vomiting, diarrhea, and heart rhythm problems. In some cases, digoxin toxicity is life-threatening.

If you take digoxin, ask your prescriber before taking vitamin D supplements. They may want to monitor your blood calcium levels more closely and possibly adjust your vitamin D dosage.

7. Thiazide diuretics, such as hydrochlorothiazide

Diuretics, sometimes called water pills, help your body get rid of excess fluid. Diuretics are prescribed for several conditions, including high blood pressure.

Hydrochlorothiazide (Microzide) belongs to a class of diuretics called thiazides. Thiazides help your body get rid of excess water, but they also decrease how much calcium your body gets rid of. As a result, calcium can build up in your bloodstream.

Vitamin D increases calcium absorption. So taking thiazides and vitamin D can make hypercalcemia (high calcium levels) more likely. Hypercalcemia can lead to health problems, such as kidney stones and abnormal heart rhythm.

If you’re over 65, have existing kidney problems, or have hyperparathyroidism, your risk of developing hypercalcemia is higher. If you take a diuretic, ask your prescriber before taking vitamin D supplements. They’ll know if vitamin D is safe to take with your medication.

Frequently asked questions about vitamin D interactions

Can you take vitamin D with blood pressure pills?

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Medications used to treat high blood pressure are generally safe to take with vitamin D supplements. Examples include:

• Angiotensin-converting enzyme (ACE) inhibitors, such as lisinopril (Zestril, Qbrelis)
• Angiotensin II receptor blockers (ARBs), such as losartan (Cozaar)
• Calcium channel blockers, such as amlodipine (Norvasc)
• Beta blockers, such as metoprolol (Toprol XL, Lopressor)

In fact, some research shows that taking vitamin D supplements may help lower blood pressure in people with high blood pressure and vitamin D deficiency.

But thiazides can increase your risk of hypercalcemia when taken with vitamin D supplements. Since hydrochlorothiazide is a first-choice medication for high blood pressure, it’s important to let your prescriber know if you take this medication.

Do steroids interact with vitamin D?

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The bottom line

Vitamin D helps you maintain strong bones and supports your overall health. The best way to get vitamin D is from sun exposure. You can also get it from foods. But if you have low vitamin D levels, a healthcare professional may recommend a vitamin D supplement. Examples include vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol).

Some medications can cause drug interactions when taken with vitamin D. This can increase your risk of side effects or prevent your body from absorbing vitamin D. Examples of medications that can interact with vitamin D include atorvastatin (Lipitor), orlistat (Xenical, Alli), and hydrochlorothiazide (Microzide). Other examples include rifampin (Rimactane), phenytoin (Dilantin, Phenytek), and digoxin (Lanoxin).

Give your healthcare team a list of all the medications you take before taking vitamin D. They can check for vitamin D interactions and determine if you need to make changes to your medication regimen.

Why trust our experts?

Written by:

Rosanna Sutherby, PharmD

Rosanna Sutherby, PharmD, has been a community pharmacist in North Carolina for over 23 years. Before beginning her work as a medical writer, she held positions as a pharmacy manager, staff pharmacist, and immunizer.

Edited by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

Reviewed by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

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References

Aihara, S., et al. (2019). Severe hypocalcemia and resulting seizure caused by vitamin D deficiency in an older patient receiving phenytoin: Eldecalcitol and maxacalcitol ointment as potential therapeutic options for hypocalcemia. Case Reports in Nephrology.

Chattopadhyay, N., et al. (2018). CYP3A4‐mediated effects of rifampicin on the pharmacokinetics of vilaprisan and its UGT1A1‐mediated effects on bilirubin glucuronidation in humans. British Journal of Clinical Pharmacology.

View All References (6)

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