8 Medications You Shouldn’t Combine With Vitamin D

Vitamin D is an essential vitamin that plays a role in inflammation and metabolism (creating energy).

The two main forms of vitamin D are ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Vitamin D is necessary to treat and lower the risk of conditions related to low vitamin D levels, like rickets and osteoporosis.

You can get vitamin D from your diet, direct sun exposure, or as a supplement. It may interact with other medications and supplements you may be taking, so talk with your healthcare provider before starting vitamin D if you take other medications.

HMG-CoA reductase inhibitors, better known as statins, are medications taken to lower cholesterol levels. Examples of statins include Lipitor (atorvastatin), lovastatin, and Zocor (simvastatin).

Vitamin D may lower how well a statin is absorbed in your blood and travels through your body. A few small studies have shown that vitamin D supplements can lower the amount of statin medication found in your body. However, the risk of this affecting your blood fat (such as lipids and cholesterol) levels is low.

Statins may interact with vitamin D in several ways. Vitamin D is created in the body with the help of a certain type of cholesterol. Taking a medication that lowers cholesterol, such as statins, may impact the natural creation of vitamin D.

Statins and vitamin D are also metabolized (broken down) by the same liver enzyme, cytochrome P450 3A4 (CYP3A4). If you take both vitamin D and a statin, they will compete for the enzyme. This leads to higher levels of one drug (usually vitamin D) in the body and lower levels of the other. More research is needed to understand how these potential interactions affect vitamin D and statins.

It is generally safe to take vitamin D and a statin medication together. Tell your healthcare provider if you are taking a statin with vitamin D. They will watch your cholesterol levels closely or change your cholesterol medication if needed.

Orlistat is a medication taken to help with weight loss. It can be taken as a prescription (Xenical) or purchased over the counter (Alli).

Orlistat breaks down fat from your diet, blocking it from being absorbed in the stomach and intestines and eliminating it through your stool. The medication can also block vitamin D absorption in your stomach and intestines, lowering the overall amount of vitamin D in your body from diet and supplementation.

Talk with your healthcare provider if you are taking orlistat and vitamin D. They will likely monitor your vitamin D levels and recommend that you separate taking both medications by at least two hours.

Thiazide diuretics, also called water pills, treat heart and blood vessel conditions and help you eliminate extra fluid. Examples of thiazide diuretics include hydrochlorothiazide and chlorothiazide.

The drug interaction between vitamin D and thiazide diuretics is related to how vitamin D affects calcium levels. Vitamin D helps your body absorb calcium in the stomach and move the mineral to other areas for use. Both calcium and vitamin D are necessary for numerous body functions, including bone health and muscle contractions.

Thiazide diuretics increase calcium levels in the blood by lowering the amount of calcium lost through urine. Taking thiazides with vitamin D can also cause higher calcium levels (hypercalcemia). The risk for hypercalcemia is higher in older adults or people with kidney disease.

The risk of interaction is higher with larger doses of vitamin D. If you are concerned about a drug interaction between a thiazide diuretic and vitamin D, talk with your healthcare provider.

Corticosteroids are often prescribed to decrease inflammation and treat health conditions like ulcerative colitis or asthma. Examples of corticosteroids include prednisone, hydrocortisone, and dexamethasone.

Research may indicate that steroids can decrease calcium absorption, affecting how well vitamin D is absorbed and used in the body. Some studies have reported that low vitamin D levels are more common in people taking steroids.

Other studies have not found a direct relationship between vitamin D levels and corticosteroid use. They report that the lower vitamin D levels may be related to a person’s diet, sun exposure, and the effect of steroids on bone health.

Bile acid sequestrants are medications prescribed to lower cholesterol and blood sugar levels. Examples include cholestyramine, colesevelam, and colestipol.

Bile acid sequestrants bind bile acid (an acid that helps break down fat) in the intestines and prevent it from entering the blood. This forces the liver to take cholesterol from the blood to make more bile acid, lowering cholesterol levels.

The drug can also bind other drugs, including vitamin D, in the stomach and intestines, lowering the amount of vitamin D in the body. Data on this interaction is limited.

If you are taking a bile acid sequestrant and vitamin D, you should separate when you take each medication. For example, you can take vitamin D at least four hours before a bile acid sequestrant.

Lanoxin (digoxin) is a medication prescribed to treat heart conditions like atrial fibrillation and heart failure.

Taking high doses of vitamin D can increase your risk for hypercalcemia, where there is too much calcium in the blood. High calcium levels can increase your risk for abnormal heart rhythms (arrhythmias) if you also take digoxin.

If you avoid taking vitamin D above the tolerable upper level of 4,000 International Units (IU) daily, the interaction risk is low. If you take digoxin and vitamin D, your healthcare provider will likely monitor your digoxin, vitamin D, and calcium levels.

Cardizem (diltiazem) is a medication prescribed to treat certain heart and blood vessel conditions.

The interaction between vitamin D and diltiazem is related to how both drugs affect calcium levels. High doses of vitamin D can increase your risk for hypercalcemia. High calcium levels can increase your risk for arrhythmias if you are also taking diltiazem.

The interaction risk between diltiazem and vitamin D is low if taking vitamin D below the tolerable daily upper level of 4,000 IU. If taking diltiazem and vitamin D, let your healthcare provider know. They will closely monitor your calcium and vitamin D levels.

Mineral oil is an over-the-counter (OTC) laxative used to treat constipation. Mineral oil blocks water absorption in your colon, which softens your stool and makes it easier to have a bowel movement.

Vitamin D is a fat-soluble vitamin, meaning it is absorbed in your body with fats and oils from your diet. Mineral oil may interact with vitamin D by keeping the vitamin in the intestines, decreasing its ability to be absorbed and used in other areas.

The severity of an interaction between vitamin D and mineral oil is low, especially since mineral oil should only be taken as needed. Let your healthcare provider know you take vitamin D before you begin taking mineral oil. They will likely recommend separating your vitamin D dose from the mineral oil by a few hours.

Vitamin D does not appear to interact with many supplements. However, there are a few supplements you should closely monitor if taking with vitamin D:

• Calcium: At normal doses, taking vitamin D with calcium helps with calcium absorption in the intestines and throughout the body. However, high doses of vitamin D can lead to high calcium levels in certain people. Adding additional calcium supplementation may lead to even higher blood calcium levels, which can be harmful.
• Magnesium: Vitamin D may increase magnesium absorption in the body because the same protein that moves calcium through the intestines can also pick up and move magnesium. Some studies have found that taking vitamin D may improve magnesium levels in people with low magnesium and vitamin D levels. This effect is not likely in people with normal magnesium levels.

Most drug interactions related to vitamin D supplementation lead to decreased absorption and lower levels of the interacting medication in the body.

Some interactions can also lead to hypercalcemia. Symptoms of hypercalcemia include nausea, vomiting, increased thirst, frequent urination, muscle weakness, bone pain, and confusion. If you begin experiencing any of these symptoms, see a healthcare provider.

If taking medications for arrhythmias or other heart conditions, monitor for any signs or symptoms of worsening arrhythmias. Symptoms include fast or slow heart rate, feeling like your heart is skipping a beat, dizziness, lightheadedness, shortness of breath, chest pain, or sweating. See a healthcare provider immediately if you experience any of these symptoms.

Vitamin D is an essential vitamin required for a number of processes in your body, like inflammation and metabolism. It also treats and lowers the risk of conditions related to low vitamin D levels, like rickets and osteoporosis.

Vitamin D can be obtained from your diet, direct sun exposure, or taken as a supplement. It may interact with other medications and supplements you are taking, such as statins, thiazide diuretics, and magnesium.

Talk with your healthcare provider before starting vitamin D, especially if you take other medications. They can help you determine whether any medications seriously interact with the vitamin.