Ergocalciferol (Vitamin D2)
Common brand names:
Calciferol
Uses
Vitamin D (ergocalciferol-D2, cholecalciferol-D3, alfacalcidol) is a fat-soluble vitamin that helps your body absorb calcium and phosphorus. Having the right amount of vitamin D, calcium, and phosphorus is important for building and keeping strong bones. Vitamin D is used to treat and prevent bone disorders (such as rickets, osteomalacia). Vitamin D is made by the body when skin is exposed to sunlight. Sunscreen, protective clothing, limited exposure to sunlight, dark skin, and age may prevent getting enough vitamin D from the sun.
Vitamin D with calcium is used to treat or prevent bone loss (osteoporosis). Vitamin D is also used with other medications to treat low levels of calcium or phosphate caused by certain disorders (such as hypoparathyroidism, pseudohypoparathyroidism, familial hypophosphatemia). It may be used in kidney disease to keep calcium levels normal and allow normal bone growth. Vitamin D drops (or other supplements) are given to breastfed infants because breast milk usually has low levels of vitamin D.
How to Use This Medication
Take vitamin D by mouth as directed. Vitamin D is best absorbed when taken after a meal but may be taken with or without food. Alfacalcidol is usually taken with food. Follow all directions on the product package. If you have any questions, ask your doctor or pharmacist.
If your doctor has prescribed this medication, take as directed by your doctor. Your dosage is based on your medical condition, amount of sun exposure, diet, age, and response to treatment.
If you are using the liquid form of this medication, carefully measure the dose using a special measuring device/spoon. Do not use a household spoon because you may not get the correct dose.
If you are taking the chewable tablet or wafers, chew the medication thoroughly before swallowing. Do not swallow whole wafers.
If you are taking the rapidly-dissolving tablets, dry your hands before handling the medication. Place each dose on the tongue, allow it to dissolve completely, and then swallow it with saliva or water. You do not need to take this medication with water.
Certain medications (bile acid sequestrants such as cholestyramine/colestipol, mineral oil, orlistat) can decrease the absorption of vitamin D. Take your doses of these medications as far as possible from your doses of vitamin D (at least 2 hours apart, longer if possible). It may be easiest to take vitamin D at bedtime if you are also taking these other medications. Ask your doctor or pharmacist how long you should wait between doses and for help finding a dosing schedule that will work with all your medications.
Take this medication regularly to get the most benefit from it. To help you remember, take it at the same time each day if you are taking it once a day. If you are taking this medication only once a week, remember to take it on the same day each week. It may help to mark your calendar with a reminder.
If your doctor has recommended that you follow a special diet (such as a diet high in calcium), it is very important to follow the diet to get the most benefit from this medication and to prevent serious side effects. Do not take other supplements/vitamins unless ordered by your doctor.
If you think you may have a serious medical problem, get medical help right away.
Copyright © 2025 TraceGains, Inc. All rights reserved.
RxAnswers™ is a copyrighted combined product from TraceGains and First DataBank, Inc.
Drug information is selected from data included with permission and copyrighted by First DataBank, Inc. This is a summary and does not contain all possible information about this product. For complete information about this product or your specific health needs, ask your healthcare professional. Always seek the advice of your healthcare professional if you have any questions about this product or your medical condition. This information is not intended as individual medical advice and does not substitute for the knowledge and judgment of your healthcare professional. This information does not contain any assurances that this product is safe, effective or appropriate for you.
This information is intended only for residents of the United States. Products sold under the same brand names in other countries may contain different ingredients.
Learn more about First DataBank
There are some limitations on the information provided in “Nutrient Interactions.” Do NOT rely solely on the information in this article. Please read the disclaimer.
Learn more about TraceGains, the company.
TraceGains and/or its suppliers make no warranties or representations as to the accuracy or completeness of this content herein or that of any organization referred or linked to within this content and will not be liable for any damages arising out of your access to or use of any information found herein or that of any organization referred to within this content.
Information expires December 2025.