Vitamin D is essential to maintaining a healthy immune system and strong bones. It might also be useful in preventing many chronic diseases including cancer. Vitamin D regulates the amount of minerals such as calcium in the body. Because of this, there is a potential for interactions with some common drugs. If you are taking a prescription medication, talk to your doctor or pharmacist before taking vitamin D supplements.
If you are taking a diuretic, also called a water pill, your medication can increase your body's ability to absorb calcium. This can be a problem when combined with vitamin D, which also increases the absorption of calcium. If you absorb too much calcium, you may experience serious side effects including kidney problems. Some common diuretics include thiazide, chlorothiazide, hydrochlorothiazide, indapamide, metolazone and chlorthalidone.
Vitamin D can increase the body's absorption of aluminum, a common ingredient in many antacids. This can be a problem, particularly if you have kidney disease. To avoid the problem, take vitamin D at least two hours before or four hours after you take an antacid. Also, if you take certain antacids for a long-time, they may impair your body's ability to absorb vitamin D, according to the University of Maryland Medical Center.
Calcium affects the heart and because vitamin D increases calcium levels, it can cause problems with a number of common heart medications or drugs that affect the heart. Do not take vitamin D with a heart medication unless you have talked to your doctor first. Some heart medications affected by vitamin D are digoxin and calcium channel blockers like diltiazem, verapamil, nifedipine, nicardipine and amlodipine. Vitamin D can also reduce the effectiveness of some cholesterol lowering drugs known as statins, including atorvastatin and lovastatin, which are used to reduce a major risk factor for heart disease.
Vitamin D may speed up how fast the liver breaks down certain drugs, which may reduce their effectiveness, according to MedlinePlus. Many drugs fall into this category so be sure to ask your doctor or pharmacist about any medications you are taking before taking a vitamin D supplement. Some common drugs whose effectiveness may be reduced by vitamin D are clarithromycin, cyclosporine, estrogens, indinavir and triazolam. Also, the psoriasis drug calcipotriene is chemically similar to vitamin D and taking the two together may increase the risk of side effects. Some drugs may lower vitamin D levels, including anti-seizure medications, the cholesterol-lowering drugs known as bile acid sequestrants, the tuberculosis drug rifampin, mineral oil, laxatives, steroids and the weight loss drug orlistat.