What's the difference between over the counter vitamin D and prescription vitamin D?

1 answer | Last updated: Sep 20, 2016
Shell51 oh/ia asked...

What's the difference between over the counter vitamin D and prescription vitamin D? For low vitamin D level.


Expert Answers

Pharmacist William Simonson, also known as "Dr. Si", is a board-certified geriatric pharmacist who is dedicated to improving medication use by seniors. He is a pharmacy educator and is active in publishing and presenting to health professional and consumer audiences and has been active in the area of geriatrics and long-term care pharmacy practice for more than 35 years.

Vitamin D is commonly available in two different forms; D-2 (ergocalciferol) and D-3 (cholecalciferol). Either one can be used to treat vitamin D deficiency although there is some evidence that vitamin D-3 is more potent and more effective than vitamin D-2 in reversing vitamin D deficiency.

When someone is deficient physicians will often prescribe 50,000 International Units of vitamin D-2 to be given weekly for 8-12 weeks. That dosage is only available by prescription. After that initial therapy which should increase the vitamin D level to greater than 30 ng/ml the dose is typically reduced to a daily dose ranging from 1,000 to 2,000 International Units per day which can be purchased without a prescription. The Institute of Medicine states that the daily vitamin D dose for adults should not exceed 4,000 International Units per day.