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Vitamin D

Brand names: Ergocalciferol (D2, Drisdol), Cholecalciferol (D3)

Vitamin D helps the body absorb calcium for strong bones. Supplements treat and prevent low vitamin D.

Brand namesErgocalciferol (D2, Drisdol), Cholecalciferol (D3)
Type of medicineVitamin
Prescription?Over the counter; high-dose capsules by prescription
ImportantThis page is general information, not a prescription. Don't start, stop, or change a medicine without talking to your provider or pharmacist.

Overview

Many people get less from sunlight in winter. A blood test can check levels.

What it's used for

  • Vitamin D deficiency
  • Bone health and osteoporosis (with calcium)
  • Breastfed babies (daily drops)

How to take it

  • Take it with a meal that has some fat for better absorption.
  • High-dose prescription capsules are often taken once a week; follow your label exactly.

Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.

Side effects

Common side effects

  • Usually none at normal doses
Call your provider todayNausea, vomiting, constipation, confusion, extreme thirst, or peeing a lot (too much vitamin D raising calcium)

Warnings

  • Too much can build up and raise calcium. Don't take extra high doses without testing.
  • Ask a provider if you have kidney disease, sarcoidosis, or high calcium.

Other medicines, foods, and alcohol

  • Thiazide water pills plus vitamin D and calcium can raise calcium.
  • Some seizure medicines and steroids lower vitamin D.

Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.

Pregnancy and breastfeeding

Usual amounts are part of prenatal vitamins. Ask before taking high doses.

Missed doses, overdose, and storage

If you miss a dose

Take it as soon as you remember, unless it's almost time for your next dose. Then skip the missed dose. Don't take two doses at once.

If someone takes too much

Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.

Storing it

Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.

Conditions it's used for

Sources

Last updated 2026-11-13.