Medications to avoid combining with vitamin D include statins and thiazide diuretics. These interactions can affect calcium and cholesterol levels in your body.12
1. Statins
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.2
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.321
2. Orlistat
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.4 The medication can also block vitamin D absorption, lowering the overall amount in your body.1
Your doctor may recommend separating the medications by at least two hours.4
3. Thiazide Diuretics
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.1
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.41
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.2
