For individuals taking vitamin D without a prescription :
If you are taking this drug for a reason other than as a dietary supplement, your family doctor must check your progress at regular appointments to make sure that it does not cause unwanted effects.
Do not take any nonprescription - over-the-counter "OTC " drug or dietary supplement that contains calcium, phosphorus, or vitamin D while you are taking any of these dietary supplements unless you have been told to do so by your health care professional. The extra calcium, phosphorus, or vitamin D may increase the risk of side effects.
Do not take antacids or other medication containing magnesium while you are taking any of these medication. Taking these medication together may cause unwanted effects .