Medications to avoid combining with vitamin D include statins and thiazide diuretics. These interactions can affect calcium and cholesterol levels in your body.
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. However, the risk of this affecting your blood lipids (cholesterol) 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 affect 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 compete for the same enzyme, leading to higher levels of one drug (usually vitamin D) and lower levels of the other.
Orlistat is a medication used to promote weight loss. It can be taken as a prescription (Xenical) or purchased over the counter (Alli).
Orlistat breaks down dietary fat, preventing its absorption in the stomach and intestines and eliminating it through your stool. The medication can also block vitamin D absorption, lowering the overall amount in your body.
Your doctor may recommend separating the 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 contraction.
Thiazide diuretics increase calcium levels in the blood by lowering the amount you lose 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 this drug interaction, 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.
Steroids may decrease calcium absorption, affecting how well vitamin D is absorbed and used in the body. Some studies suggest low vitamin D levels are more common in people taking steroids, but other studies do not find this connection.
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 (which 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 to other drugs, including vitamin D, in the stomach and intestines, reducing the body’s vitamin D levels.
If you are taking a bile acid sequestrant and vitamin D, it’s best to take vitamin D at least four hours before the 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.
As long as you don’t exceed the tolerable upper level of for vitamin D, which is 4,000 International Units (IU) daily, the interaction risk is low.
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.
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, absorbed in your body with fats and oils from your diet. Mineral oil may keep the vitamin in the intestines, decreasing its ability to be absorbed and used in other areas.
The severity of the interaction between vitamin D and mineral oil is low, particularly since mineral oil should be used only as needed.
Healthcare providers typically recommend separating your vitamin D dose from the mineral oil by a few hours.
Vitamin D does not appear to interact with many supplements. A few supplements may need to be closely monitored if taken with vitamin D:
Calcium: At normal doses, taking vitamin D with calcium helps with calcium absorption. However, high doses of vitamin D can lead to high calcium levels in certain people, 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.
Most drug interactions related to vitamin D supplementation lead to decreased absorption and lower levels of the interacting medication.
Some interactions can also lead to hypercalcemia. Symptoms of hypercalcemia include nausea, vomiting, increased thirst, frequent urination, muscle weakness, bone pain, and confusion.
If taking medications for arrhythmias or other heart conditions, it’s important to monitor for any signs or symptoms of worsening arrhythmias.
Symptoms include a rapid or slow heart rate, a sensation of skipped beats, dizziness, lightheadedness, shortness of breath, chest pain, or sweating.
If you begin experiencing any of these symptoms, speak with a healthcare provider.