What is Vitamin D3: Uses, Warnings & Interactions

Medically reviewed by Marissa Walsh, Pharm.D., BCPS-AQ ID
Licensed Pharmacist
Updated Sep 2, 2025  •  Published Dec 30, 2020
Fact Checked

Vitamin D3 is a fat-soluble vitamin called cholecalciferol. Its most important function is keeping calcium levels in the body and bones at healthy levels. Without vitamin D, the body has problems absorbing calcium from foods, keeping it in the body, and depositing it in the bones. People normally get enough vitamin D3 from foods and sunlight. Vitamin D3 supplements can help restore or maintain healthy vitamin D levels if that's not enough.

Check our best Vitamin D3 prices

Vitamin D3 overview

BRAND NAMES:

  • ADK 20, Calcigen D3, D2000, Ddrops, Decalcitrol, Decara, D-Force, ImmunD3, Liqui-D3, Maxi D3. Osteo-Vit3, Replesta, Sunshine D, Vita-Desic

Generic Names:

  • Vitamin D3, cholecalciferol

Uses:

  • Used to supplement the diet, treat vitamin D deficiency, prevent osteoporosis, or improve bone health.

Therapeutic Classes:

  • Dietary supplement, vitamin, nutriceutical

Forms:

  • Capsule/softgel, tablet, chewable, melts/oral strip, gummy, liquid/drops, skin patch

How it’s taken:

  • By mouth

What is Vitamin D3 used for?

Vitamin D3 is a dietary supplement primarily used to maintain healthy vitamin D levels or promote bone health. Healthcare providers use vitamin D3 to treat vitamin D deficiency or to supplement the diet of people with medical conditions associated with low vitamin D. Nursing mothers are advised to give their babies vitamin D3 to prevent bone growth problems or rickets.

Key takeaways

  • Vitamin D3 helps the body absorb calcium, which is critical for bone health. It also supports the immune system, muscles, and cardiovascular health. 

  • The main sources of vitamin D3 include sunlight and certain foods, like fatty fish, egg yolks, and other fortified foods. Therefore, taking any supplementation with fat-containing foods helps with absorption. Think avocado, nuts, and olive oil. 

  • Doses of vitamin D3 supplementation will depend on the goal–bone health versus correcting a deficiency, for example. Generally, 1 mcg is equivalent to 40 international units (IUs). 

  • The best time to take vitamin D3 supplementation is in the morning or midday. Taking vitamin D3 at night may interfere with sleep in some individuals. 

  • Blood levels, measured as 25-hydroxyvitamin D, can be obtained to determine if supplementation doses are sufficient. A range of 20-40 ng/mL is generally considered sufficient. Levels less than 20 ng/mL are considered deficient, while levels exceeding 60-80 ng/mL may cause toxicity concerns, including kidney damage or heart arrhythmias.

What form(s) does Vitamin D3 come in

  • Capsule/softgel

    • 400 IU

    • 600 IU

    • 1,000 IU 

    • 2,000 IU

    • 5,000 IU

    • 10,000 IU

    • 50,000 IU

  • Tablet

    • 400 IU

    • 800 IU

    • 1,000 IU

    • 2,000 IU

    • 3,000 IU

    • 5,000 IU

    • 10,000 IU

    • 50,000 IU

  • Chewable (tablets, wafers, chews)

    • 400 IU

    • 1,000 IU 

    • 2,000 IU

    • 5,000 IU

    • 10,000 IU

    • 14,000 IU

    • 50,000 IU

  • Gummy

    • 1,000 IU

    • 2,000 IU

    • 2,500 IU

    • 3,000 IU

    • 4,000 IU

    • 5,000 IU

    • 10,000 IU

  • Melts/oral strip/dissolvables

    • 1,000 IU

    • 2,000 IU

    • 5,000 IU

    • 10,000 IU

    • 25,000 IU

    • 40,000 IU

  • Liquid/drops

    • 400 IU

    • 600 IU

    • 640 IU

    • 1,000 IU

    • 2,000 IU

    • 2,500 IU

    • 5,000 IU

    • 10,000 IU

  • Patch

    • 5,000 IU

    • 5,300 IU

    • 5,500 IU

    • 10,000 IU

    • 16,000 IU

This is not an all-inclusive list. Given the number of generic products available, additional strengths may be available at your local pharmacy, typically ranging from 400 IU to 50,000 IU.

What are common Vitamin D3 doses?

  • Recommended daily intake:

    • For adults and children 1 year of age and older: 15 mcg/day (600 IU/day) 

    • For children 0–12 months: 10 mcg/day (400 IU/day)

  • For osteoporosis prevention in adults 50 years of age or older: 800–1,000 IU daily

  • For vitamin D deficiency: 

    • In adults: 6,000 IU daily or 50,000 IU weekly for eight weeks

    • In children: 2,000 IU daily or 50,000 IU weekly for six weeks

Common Vitamin D3 prescriptions

  • Vitamin D3
    100 capsules bottle

  • Vitamin D3
    100 tablets bottle

  • Vitamin D3
    110 tablets chewable bottle

  • Vitamin D3
    12 capsules bottle

  • Vitamin D3
    150 capsules bottle

  • Vitamin D3
    180 tablets bottle

  • Vitamin D3
    200 tablets bottle

  • Vitamin D3
    250 capsules bottle

  • Vitamin D3
    30 capsules bottle

  • Vitamin D3
    350 capsules bottle

  • Vitamin D3
    52ml of 10mcg/ml bottle

  • Vitamin D3
    59ml of 125mcg/0.5ml bottle

  • Vitamin D3
    72 capsules bottle

  • Vitamin D3
    90 tablets bottle

  • Vitamin D3
    10 mcg(400 unit) tablet

  • Vitamin D3
    25 mcg(1000 ut) tablet

How to take Vitamin D3

  • Your doctor will tell you how much medicine to use. Use only directed.

  • If you take vitamin D3 without a prescription, only take the recommended dose printed on the label.

  • How to take vitamin D3 tablets or capsules:

    • Follow the instructions on the label.

    • Vitamin D3 can be taken with or without food. Taking with high-fat meals may improve absorption.

    • Swallow the capsule or tablet whole.

  • How to take vitamin D3 chewables or gummies:

    • Follow the instructions on the label.

    • Chew or crush the tablet or chew the gummy before swallowing. Do not swallow whole.

  • How to take vitamin D3 dissolvables, strips, or melts:

    • Follow the instructions on the label.

    • Allow the film or tablet to completely dissolve in the mouth before swallowing. Do not swallow whole.

  • How to use vitamin D3 liquid: 

    • Use the dropper that comes with the package to measure the dose.

    • Drop the liquid directly into the mouth or mix it with food or other liquids (water or juice).

    • If you’re giving the drops to children younger than 2 years of age, place one drop of the liquid on the pacifier, mother's nipple, or bottle nipple and allow the baby to suck for at least 30 seconds.

  • How to use vitamin D3 patches:

    • Follow the instructions on the label. These instructions will differ between products.

    • Do not exceed the recommended dosage.

    • Place the patch on clean, hairless skin.

  • Consult the package labeling for storage instructions. Most vitamin D3 products should be stored in a closed container at room temperature.

What to do if you miss a dose of Vitamin D3

  • If a dose is missed, take it when remembered.

  • Do not exceed the recommended daily dosage to make up for a missed dose.

Vitamin D3 contraindications

  • This medicine is generally considered safe for most people. Talk to your doctor if you have concerns.

  • Do not take a vitamin D3 product if you are allergic to any of the ingredients in the product.

Vitamin D3 warnings

  • Check with your doctor before taking vitamin D3 supplements if you are pregnant or breastfeeding.

    • Vitamin D3 is normally safe to take while pregnant or breastfeeding, but if vitamin D deficiency is an issue, a pregnant or breastfeeding woman may require supplementation.

    • Infants exclusively breastfed may require vitamin D supplementation to prevent bone growth problems or rickets.

  • If a doctor prescribes vitamin D3, the doctor may need to see you and perform blood tests regularly to monitor the effects of supplementation. Keep all appointments.

  • Taking excessive amounts of vitamin D supplements can, over time, cause vitamin D poisoning, a rare but potentially serious condition. Extremely large doses increase the risk of falls and fractures. Do not exceed the recommended daily allowance unless advised by a doctor.

Vitamin D3 interactions

  • If you take other medications, talk to a doctor before taking vitamin D3 supplements.

  • Tell any doctor prescribing new medications that you are taking vitamin D3.

  • The absorption of oral vitamin D3 is partly blocked in people taking drugs that block fat absorption or bile in the digestive system, including:

    • The cholesterol-lowering drugs cholestyramine or colestipol

    • The weight loss drug orlistat

Vitamin D3 side effects

Serious side effects

Serious side effects due to taking vitamin D3 are either the result of allergic reactions or chronic overdosing (vitamin D poisoning). Talk to a doctor if you notice any signs or symptoms of a possible serious side effect, including:

  • Vitamin D poisoning: weakness, fatigue, loss of appetite, bone pain, nausea, abdominal pain, vomiting, excessive thirst, excessive urination, confusion, sluggishness, mood changes

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing

Vitamin D3 News & Research

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10 foods high in vitamin D

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Medically reviewed by Marissa Walsh, Pharm.D., BCPS-AQ ID
Licensed Pharmacist

Marissa Walsh, Pharm.D., BCPS-AQ ID, graduated with her Doctor of Pharmacy degree from the University of Rhode Island in 2009, then went on to complete a PGY1 Pharmacy Practice Residency at Charleston Area Medical Center in Charleston, West Virginia, and a PGY2 Infectious Diseases Pharmacy Residency at Maine Medical Center in Portland, Maine. Dr. Walsh has worked as a clinical pharmacy specialist in Infectious Diseases in Portland, Maine, and Miami, Florida, prior to setting into her current role in Buffalo, New York, where she continues to work as an Infectious Diseases Pharmacist in a hematology/oncology population.

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