How does vitamin D2 work?

Vitamin D2 is classified as a fat-soluble vitamin (absorbs best with fat). It works in the body by helping you absorb much needed calcium and phosphate. Vitamin D2 can also be found in mushrooms or yeast.

What drugs should not be taken with vitamin D2?

There are a few medications that may interact with vitamin D2, including thiazide diuretics (hydrochlorothiazide, metolazone). Thiazide diuretics and vitamin D2 together may cause too much calcium in the body (hypercalcemia). Hypercalcemia symptoms include dehydration, an irregular heartbeat, confusion, muscle spasms, bone and joint pain. It is always best to tell your healthcare provider about all of the prescription medications, over-the-counter medications, vitamins, supplements, or herbs you are taking, before starting any new medications. Supplements and herbs can have significant health effects, as well as cause interactions with medication.

Vitamin D2 (Ergocalciferol) - Oral: Uses, Effects

What Is Vitamin D2?

Vitamin D2 (ergocalciferol) is available as a prescription and over-the-counter medication. It is a vitamin D analog and fat-soluble vitamin (it needs fat to absorb well) that helps your body absorb phosphorus and calcium.

Foods that contain vitamin D2 include mushrooms and yeast.

Drug Facts

Generic Name: Vitamin D2

Brand Name(s): Ergocalciferol

Drug Availability: Prescription, OTC

Therapeutic Classification: Vitamin D Supplements

Available Generically: Yes

Controlled Substance: No

Administration Route: Oral

Active Ingredient: Ergocalciferol

Dosage Form(s): Capsule

What Is Vitamin D2 Used For?

Overall vitamin D is important for good health. It plays a key role in the immune system, muscle movement, and the nervous system. Vitamin D2, specifically, is often prescribed to treat:

Vitamin D deficiency (e.g., in people with conditions that can block fat absorption: celiac, Crohn’s disease, or ulcerative colitis or those who have undergone gastric bypass surgery)
Refractory rickets
Hypophosphatemia (low levels of phosphate)
Hypoparathyroidism (low levels of parathyroid hormone)

How to Take Vitamin D2

Ergocalciferol is available as a capsule meant to be taken by mouth. How often you take ergocalciferol depends on what condition you are using it to treat and how your body reacts to the medication. This medication can be taken with or without food.

Storage

Keep your medications tightly closed and out of the reach of children and pets, ideally locked in a cabinet or closet. Store at room temperature (68 to 77 degrees Fahrenheit). Do not store your medication in the bathroom.

Avoid pouring unused and expired drugs down the drain or in the toilet. Ask your pharmacist or healthcare provider about the best ways to dispose of this medicine. Visit the FDA's website to know where and how to discard all unused and expired drugs. You can also find disposal boxes in your area. Ask your pharmacist or healthcare provider if you have any questions about the best ways to dispose of your medications.

If you travel with vitamin D2, get familiar with your final destination's regulations. Make a copy of your vitamin D2 prescription, and keep your medication in its original container from the pharmacy with your name on the label. Ask your pharmacist or healthcare provider if you have any questions about traveling with your medicine.

How Long Does Vitamin D2 Take to Work?

The time it takes vitamin D2 to work may be different for everyone. Depending on the level of your deficiency, it could take up to a few months for it to work. Check with your healthcare provider or pharmacist if you have any questions.

What Are the Side Effects of Vitamin D2?

Like most medications, ergocalciferol can cause mild or serious side effects.

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or healthcare provider. You may report side effects to the Food and Drug Administration (FDA) at fda.gov/medwatch or 800-FDA-1088.

Common Side Effects

Common side effects of vitamin D2 may include but may not be limited to:

Nausea
Constipation

If any of these side effects don’t go away or become more severe, talk to your healthcare provider or pharmacist.

Severe Side Effects

Example text: Contact your healthcare provider immediately if you develop signs of a severe reaction. Call 911 if your symptoms feel life-threatening.

Severe side effects of vitamin D2 may include but may not be limited to:

Allergic reaction (e.g., hives, trouble breathing, swelling of the lips, tongue, or throat)
Chest pain
Shortness of breath
Weight loss
Muscle or bone pain

Long-Term Side Effects

Long-term side effects of too much vitamin D include:

High blood calcium levels (hypercalcemia)
Kidney stones

Report Side Effects

Vitamin D2 may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the FDA's MedWatch Adverse Event Reporting Program online or by phone (800-332-1088).

(800) 332-1088

Dosage: How Much Vitamin D2 Should I Take?

The dose medicines in this class will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of these medicines. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

To treat bone disease in kidney patients undergoing kidney dialysis:
- For oral dosage form (capsules):
  - Adults and teenagers—At first, 1 microgram (mcg) a day. Your doctor may change your dose if needed. However, most people will take not more than 3 mcg a day.
- For oral dosage form (drops):
  - Adults and teenagers—At first, 1 microgram (mcg) a day. Your doctor may change your dose if needed. However, most people will take not more than 3 mcg a day.
- For oral dosage form (solution):
  - Adults and teenagers—At first, 1 mcg a day. Your doctor may change your dose if needed. However, most people will take not more than 3 mcg a day.
- For parenteral dosage form (injection):
  - Adults and teenagers—At first, 1 mcg a day. Your doctor may change your dose if needed. However, most people will take not more than 12 mcg a week.
To treat diseases in which calcium is not used properly by the body:
- For oral dosage form (capsules):
  - Adults and teenagers—At first, 0.25 microgram (mcg) a day. Your doctor may change your dose if needed. However, most people will take not more than 1 mcg a day.
- For oral dosage form (drops):
  - Adults and teenagers—At first, 0.25 microgram (mcg) a day. Your doctor may change your dose if needed. However, most people will take not more than 1 mcg a day.
- For oral dosage form (solution):
  - Adults and teenagers—At first, 0.25 mcg a day. Your doctor may change your dose if needed. However, most people will take not more than 1 mcg a day.

To treat diseases in which calcium is not used properly by the body or to treat bone disease in kidney patients undergoing kidney dialysis:
- For oral dosage form (capsules):
  - Adults, teenagers, and children over 10 years of age—At first, 300 to 350 micrograms (mcg) a week, taken in divided doses either once a day or every other day. Your doctor may change your dose if needed.
  - Children 2 to 10 years of age—50 mcg a day.
  - Children up to 2 years of age—20 to 50 mcg a day.
To treat diseases in which calcium is not used properly by the body or to treat bone disease in kidney patients undergoing kidney dialysis:
- For oral dosage forms (capsules and solution):
  - Adults, teenagers, and children—At first, 0.25 micrograms (mcg) a day. Your doctor may change your dose if needed.
- For parenteral dosage forms (injection):
  - Adults and teenagers—At first, 0.5 mcg injected into a vein three times a week. Your doctor may change your dose if needed.
  - Children—Use and dose must be determined by your doctor.

To treat diseases in which calcium is not used properly by the body:
- For oral dosage forms (capsules, solution, or tablets):
  - Adults and teenagers—At first, 100 micrograms (mcg) to 2.5 milligrams (mg) a day. Your doctor may change your dose if needed.
  - Children—At first, 1 to 5 mg a day. Your doctor may change your dose if needed.

To treat an overactive parathyroid gland in patients with kidney failure:
- For oral dosage form (capsules):
  - Adults—10 micrograms (mcg) three times weekly at dialysis. The doctor may change your dose if needed.
  - Children—Use and dose must be determined by your doctor.

The amount of vitamin D to meet normal daily recommended intakes will be different for different individuals. The following information includes only the average amounts of vitamin D.
To prevent deficiency, the amount taken by mouth is based on normal daily recommended intakes:
- For oral dosage form (capsules):
  - Adults and teenagers—5 to 10 micrograms (mcg) (200 to 400 Units) per day.
  - Pregnant and breast-feeding females—10 mcg (400 Units) per day.
  - Children 4 to 10 years of age—10 mcg (400 Units) per day.
  - Children birth to 3 years of age—7.5 to 10 mcg (300 to 400 Units) per day.
  - Adults and teenagers—2.5 to 5 mcg (100 to 200 Units) per day.
  - Pregnant and breast-feeding females—5 to 7.5 mcg (200 to 300 Units) per day.
  - Children 7 to 10 years of age—2.5 to 5 mcg (100 to 200 Units) per day.
  - Children 4 to 6 years of age—5 mcg (200 Units) per day.
  - Children birth to 3 years of age—5 to 10 mcg (200 to 400 Units) per day.
To treat deficiency:
- Adults, teenagers, and children—Treatment dose is determined by prescriber for each individual based on severity of deficiency.
To treat diseases in which calcium and phosphate are not used properly by the body:
- Adults and teenagers—At first, 1000 to 500,000 Units a day. The doctor may change your dose if needed.
- Children—At first, 1000 to 200,000 Units a day. The doctor may change your dose if needed.

To treat an overactive parathyroid gland in patients with kidney failure:
- For oral dosage form (capsules):
  - Adults—1 to 2 micrograms (mcg) one time per day or 2 to 4 mcg three times a week (not more often than every other day). The doctor may change your dose if needed.
  - Children—Use and dose must be determined by your doctor.
- For parenteral dosage form (injection):
  - Adults—0.04 to 0.1 micrograms (mcg) per kg no more than every other day during dialysis. The doctor may change your dose if needed.
  - Children—Use and dose must be determined by your doctor.

Modifications

The following modifications (changes) should be kept in mind when using vitamin D2:

Severe allergic reaction: Avoid using vitamin D2 if you have a known allergy to it or its ingredients. Ask your pharmacist or healthcare provider for a complete list of the ingredients if you're unsure.

Pregnancy: The safety of more than 400 USP units of vitamin D per day during pregnancy hasn't been established. Discuss with your healthcare provider if you plan to become pregnant or are pregnant, and weigh the benefits and risks of taking vitamin D during your pregnancy.

Breastfeeding: Use caution while using ergocalciferol during breastfeeding. In a person given large doses of vitamin D, it transferred to breast milk and caused hypercalcemia in the breastfeeding child. Monitoring an infant's serum calcium concentration may be needed. Talk with your healthcare provider if you plan to breastfeed, to weigh the benefits and risks of taking vitamin D2 while nursing and the different ways to feed your baby.

Adults over 65: Clinical studies haven't included a large enough number of people in this age group to see whether they respond differently from younger adults. Older adults with several medical conditions or who are taking several medications should use caution with vitamin D2. Older adults might also be more sensitive to vitamin D2's side effects.

Children: For breastfed infants, breast milk will not provide infants with enough vitamin D. Breastfed infants need 10 micrograms (mcg) or 400 IU of vitamin D daily.

Other modifications: The more melanin a person's skin contains (the darker it is), the more difficulty it has in processing vitamin D from sun exposure. Talk with your healthcare provider about your vitamin D needs.

Administration modifications: Getting enough calcium from your diet may be necessary for getting the most from vitamin D therapy.

Missed Dose

If you accidentally forgot your vitamin D2 dose, take it as soon as you remember. If it's already close to your next scheduled dose, then skip the missed dose and take the following dose at your next scheduled dosing time. Don't try to double up to make up for the missed dose.

Find ways to help yourself remember to keep your appointments and take your medication. If you miss too many doses, vitamin D2 might be less effective at treating or preventing your condition.

Overdose: What Happens If I Take Too Much Vitamin D2?

If you take too much vitamin D2, you may begin to experience symptoms including:

Nausea
Loss of appetite
Urinating more or less than usual
Thirst
Body aches
Confusion
Irregular heartbeat
High blood calcium levels (hypercalcemia)
Kidney stones

The effects of taking vitamin D2 can last for two or more months after you stop treatment.

What Happens If I Overdose on vitamin D2?

If you think you or someone else may have overdosed on vitamin D2, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking vitamin D2, call 911 immediately.

911

Precautions

For individuals taking vitamin D without a prescription:

Vitamin D is stored in the body; therefore, when you take more than the body needs, it will build up in the body. This may lead to poisoning. Problems are more likely to occur in:
- Adults taking 20,000 to 80,000 Units a day and more for several weeks or months.
- Children taking 2,000 to 4,000 Units a day for several months.

If you are taking this medicine for a reason other than as a dietary supplement, your doctor should check your progress at regular visits to make sure that it does not cause unwanted effects.

Do not take any nonprescription (over-the-counter [OTC]) medicine 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 chance of side effects.

Do not take antacids or other medicines containing magnesium while you are taking any of these medicines. Taking these medicines together may cause unwanted effects.

What Are Reasons I Shouldn’t Take Vitamin D2?

Avoid using it if you're allergic to vitamin D2 or its ingredients. Ask your pharmacist or healthcare provider for a complete list of the ingredients if you're unsure.

In specific individuals, the body may handle vitamin D2 differently. Let your healthcare provider know if you have the following:

Heart disease
Kidney disease
Electrolyte imbalance
High blood calcium levels (hypercalcemia)
Sarcoidosis (the collection of inflammatory cells throughout the body)

What Other Medications Interact With Vitamin D2?

Use caution when taking vitamin D2 with the following medications:

Thiazide diuretics (e.g., hydrochlorothiazide (some brand names include Microzide and Oretic as well as many other drugs where it's an ingredient), Zaroxolyn (metolazone))
Other vitamin D analogs
Lipase inhibitors (these deplete vitamin D)
Laxatives (these deplete vitamin D)

This list does not include all drugs that can interact with ergocalciferol.

Before taking vitamin D2, tell your healthcare provider about all of the prescription medications, over-the-counter medications, vitamins, supplements, herbs, or fortified foods (for example, orange juice with added calcium and vitamin D) that you are taking. This will help you avoid potential interactions.

Talk with your pharmacist or healthcare provider for more detailed information about medication interactions with vitamin D2.

What Medications Are Similar?

Two main types of vitamin D exist, vitamin D2 and vitamin D3. Both play a similar role in the body but have slightly different molecular structures. Vitamin D2 comes mainly from plants and yeast, while vitamin D3 primarily comes from animal sources (e.g., fatty fish, fish liver oil, and to a lesser extent, egg yolks, beef liver, and cheese).

Vitamin D3 (cholecalciferol) is available as an over-the-counter (OTC) medication. It is often used as a vitamin supplement for low vitamin D levels in the blood. The primary source of vitamin D is the sun, but some people may not have enough exposure and need to supplement with a vitamin. Foods that contain vitamin D3 include:

Salmon
Cod liver oil
Eggs
Cheese
Tuna
Trout

If you have questions about what vitamins, minerals, or other supplements may be best for you, speak with your provider.

Frequently Asked Questions

What is vitamin D2 used for?

In general, vitamin D plays an essential role in your overall health. Specifically, vitamin D2 can be prescribed to treat vitamin D deficiency, refractory rickets, low phosphate levels, or low levels of parathyroid hormone.
How does vitamin D2 work?

Vitamin D2 is classified as a fat-soluble vitamin (absorbs best with fat). It works in the body by helping you absorb much needed calcium and phosphate. Vitamin D2 can also be found in mushrooms or yeast.
What drugs should not be taken with vitamin D2?

There are a few medications that may interact with vitamin D2, including thiazide diuretics (hydrochlorothiazide, metolazone). Thiazide diuretics and vitamin D2 together may cause too much calcium in the body (hypercalcemia). Hypercalcemia symptoms include dehydration, an irregular heartbeat, confusion, muscle spasms, bone and joint pain. It is always best to tell your healthcare provider about all of the prescription medications, over-the-counter medications, vitamins, supplements, or herbs you are taking, before starting any new medications. Supplements and herbs can have significant health effects, as well as cause interactions with medication.

How Can I Stay Healthy While Taking Vitamin D2?

Vitamin D2 is a safe and effective medication when used correctly. This drug is often used to treat refractory rickets, low levels of phosphate, or low levels of parathyroid hormone.

While vitamin D2 has the potential for serious side effects, such as allergic reactions, chest pain, or muscle or bone pain, the most common side effects, such as nausea, tend to be mild.

It is essential to speak with your healthcare provider about your health questions and conditions and tell them about any prescription medications, over-the-counter medications, vitamins, supplements, herbs, or fortified foods that you are taking. This way, you and your healthcare provider can decide what medication and dose are safe and work best for you.

To learn more if vitamin D2 is the right medication for you, speak with your healthcare provider.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

3 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

MedlinePlus. Ergocalciferol.
DailyMed. Ergocalciferol.
U.S. National Library of Medicine. Vitamin D: fact sheet for health professionals.

By Kaylea Swearingen, PharmD
Kaylea Swearingen is a registered pharmacist and health and wellness writer.

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