Some commonly used brand names are:

In the U.S.—

In Canada—

• Antihypocalcemic
• Antihypoparathyroid
• Nutritional supplement, vitamin

Vitamins (VYE-ta-mins) are compounds that you must have for growth and health. They are needed in small amounts only and are available in the foods that you eat. Vitamin D is necessary for strong bones and teeth.

Lack of vitamin D may lead to a condition called rickets, especially in children, in which bones and teeth are weak. In adults it may cause a condition called osteomalacia, in which calcium is lost from bones so that they become weak. Your doctor may treat these problems by prescribing vitamin D for you. Vitamin D is also sometimes used to treat other diseases in which calcium is not used properly by the body.

Ergocalciferol is the form of vitamin D used in vitamin supplements.

Some conditions may increase your need for vitamin D. These include:

• Alcoholism
• Intestine diseases
• Kidney disease
• Liver disease
• Overactivity of the parathyroid glands with kidney failure
• Pancreas disease
• Surgical removal of stomach

In addition, individuals and breast-fed infants who lack exposure to sunlight, as well as dark-skinned individuals, may be more likely to have a vitamin D deficiency. Increased need for vitamin D should be determined by your health care professional.

Alfacalcidol, calcifediol, calcitriol, and dihydrotachysterol are forms of vitamin D used to treat hypocalcemia (not enough calcium in the blood). Alfacalcidol, calcifediol, and calcitriol are also used to treat certain types of bone disease that may occur with kidney disease in patients who are undergoing kidney dialysis.

Claims that vitamin D is effective for treatment of arthritis and prevention of nearsightedness or nerve problems have not been proven. Some psoriasis patients may benefit from vitamin D supplements; however, controlled studies have not been performed.

Injectable vitamin D is given by or under the supervision of a health care professional. Some strengths of ergocalciferol and all strengths of alfacalcidol, calcifediol, calcitriol, and dihydrotachysterol are available only with your doctor's prescription. Other strengths of ergocalciferol are available without a prescription. However, it may be a good idea to check with your health care professional before taking vitamin D on your own. Taking large amounts over long periods may cause serious unwanted effects.

Vitamin D and related compounds are available in the following dosage forms:

Oral
• Alfacalcidol
  • Capsules (Canada)
  • Oral solution (Canada)
  • Oral drops (Canada)
• Calcifediol
  • Capsules (U.S.)
• Calcitriol
  • Capsules (U.S. and Canada)
  • Oral solution (Canada)
• Dihydrotachysterol
  • Capsules (U.S. and Canada)
  • Oral solution (U.S.)
  • Tablets (U.S.)
• Doxercalciferol
  • Capsules (U.S.)
• Ergocalciferol
  • Capsules (U.S. and Canada)
  • Oral solution (U.S. and Canada)
  • Tablets (U.S. and Canada)

Parenteral
• Alfacalcidol
  • Injection (Canada)
• Calcitriol
  • Injection (U.S. and Canada)
• Ergocalciferol
  • Injection (U.S. and Canada)
• Paricalcitol
  • Injection (U.S.)

Vitamins alone will not take the place of a good diet and will not provide energy. Your body also needs other substances found in food such as protein, minerals, carbohydrates, and fat. Vitamins themselves often cannot work without the presence of other foods. For example, fat is needed so that vitamin D can be absorbed into the body.

The daily amount of vitamin D needed is defined in several different ways.

For U.S.—
• Recommended Dietary Allowances (RDAs) are the amount of vitamins and minerals needed to provide for adequate nutrition in most healthy persons. RDAs for a given nutrient may vary depending on a person's age, sex, and physical condition (e.g., pregnancy).
• Daily Values (DVs) are used on food and dietary supplement labels to indicate the percent of the recommended daily amount of each nutrient that a serving provides. DV replaces the previous designation of United States Recommended Daily Allowances (USRDAs).

For Canada—
• Recommended Nutrient Intakes (RNIs) are used to determine the amounts of vitamins, minerals, and protein needed to provide adequate nutrition and lessen the risk of chronic disease.

In the past, the RDA and RNI for vitamin D have been expressed in Units (U). This term has been replaced by micrograms (mcg) of vitamin D.

Normal daily recommended intakes in mcg and Units are generally defined as follows:

Remember:

• The total amount of each vitamin that you get every day includes what you get from the foods that you eat and what you may take as a supplement.
• Your total amount should not be greater than the RDA or RNI, unless ordered by your doctor. Taking too much vitamin D over a period of time may cause harmful effects.

If you are taking this dietary supplement without a prescription, carefully read and follow any precautions on the label. For vitamin D and related compounds, the following should be considered:

Allergies—Tell your health care professional if you have ever had any unusual or allergic reaction to alfacalcidol, calcifediol, calcitriol, dihydrotachysterol, doxercalciferol, ergocalciferol, or paricalcitol. Also, tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—It is especially important that you are receiving enough vitamin D when you become pregnant and that you continue to receive the right amounts of vitamins throughout your pregnancy. The healthy growth and development of the fetus depend on a steady supply of nutrients from the mother.

You may need vitamin D supplements if you are a strict vegetarian (vegan-vegetarian) and/or have little exposure to sunlight and do not drink vitamin D-fortified milk.

Taking too much alfacalcidol, calcifediol, calcitriol, dihydrotachysterol, or ergocalciferol can also be harmful to the fetus. Taking more than your health care professional has recommended can cause your baby to be more sensitive than usual to its effects, can cause problems with a gland called the parathyroid, and can cause a defect in the baby's heart.

Doxercalciferol or paricalcitol have not been studied in pregnant women. However, studies in animals have shown that paricalcitol causes problems in newborns. Before taking this medicine, make sure your doctor knows if you are pregnant or if you may become pregnant.

Breast-feeding—It is especially important that you receive the right amounts of vitamins so that your baby will also get the vitamins needed to grow properly. Infants who are totally breast-fed and have little exposure to the sun may require vitamin D supplementation. However, taking large amounts of a dietary supplement while breast-feeding may be harmful to the mother and/or baby and should be avoided.

Only small amounts of alfacalcidol, calcifediol, calcitriol, or dihydrotachysterol pass into breast milk and these amounts have not been reported to cause problems in nursing babies.

It is not known whether doxercalciferol or paricalcitol passes into breast milk. Be sure you have discussed the risks and benefits of the supplement with your doctor.

Children—Problems in children have not been reported with intake of normal daily recommended amounts. Some studies have shown that infants who are totally breast-fed, especially with dark-skinned mothers, and have little exposure to sunlight may be at risk of vitamin D deficiency. Your health care professional may prescribe a vitamin/mineral supplement that contains vitamin D. Some infants may be sensitive to even small amounts of alfacalcidol, calcifediol, calcitriol, dihydrotachysterol, or ergocalciferol. Also, children may show slowed growth when receiving large doses of alfacalcidol, calcifediol, calcitriol, dihydrotachysterol, or ergocalciferol for a long time.

Studies on doxercalciferol or paricalcitol have been done only in adult patients, and there is no specific information comparing the use of doxercalciferol or paricalcitol in children with use in other age groups.

Older adults—Problems in older adults have not been reported with intake of normal daily recommended amounts. Studies have shown that older adults may have lower blood levels of vitamin D than younger adults, especially those who have little exposure to sunlight. Your health care professional may recommend that you take a vitamin supplement that contains vitamin D.

Other medicines—Medicines or other dietary supplements

Although certain medicines or dietary supplements should not be used together at all, in other cases they may be used together even if an interaction might occur. In these cases, your health care professional may want to change the dose, or other precautions may be necessary. When you are taking vitamin D and related compounds, it is especially important that your health care professional know if you are taking any of the following:

• Antacids containing magnesium—Use of these products with any vitamin D–related compound may result in high blood levels of magnesium, especially in patients with kidney disease

• Calcium-containing preparations or
• Thiazide diuretics (water pills)—Use of these preparations with vitamin D may cause high blood levels of calcium and increase the chance of side effects

• Vitamin D and related compounds, other—Use of vitamin D with a related compound may cause high blood levels of vitamin D and increase the chance of side effects.

• Heart or blood vessel disease—Alfacalcidol, calcifediol, calcitriol, or dihydrotachysterol may cause hypercalcemia (high blood levels of calcium), which may make these conditions worse

• Kidney disease—High blood levels of alfacalcidol, calcifediol, calcitriol, dihydrotachysterol, or ergocalciferol may result, which may increase the chance of side effects

• Sarcoidosis—May increase sensitivity to alfacalcidol, calcifediol, calcitriol, dihydrotachysterol, or ergocalciferol and increase the chance of side effects

For use as a dietary supplement:

• Do not take more than the recommended daily amount . Vitamin D is stored in the body, and taking too much over a period of time can cause poisoning and even death.

If you have any questions about this, check with your health care professional.

For individuals taking the oral liquid form of this dietary supplement:

• This preparation should be taken by mouth even though it comes in a dropper bottle.
• This dietary supplement may be dropped directly into the mouth or mixed with cereal, fruit juice, or other food.

While you are taking alfacalcidol, calcifediol, calcitriol, dihydrotachysterol, doxercalciferol or paricalcitol , your health care professional may want you to follow a special diet or take a calcium supplement. Be sure to follow instructions carefully. If you are already taking a calcium supplement or any medicine containing calcium, make sure your health care professional knows.

Dosing—

The dose of these vitamin D and related compounds 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 health care professional tells you to do so.

The number of milliliters (mL) of solution that you take, or the number of capsules or tablets 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 taking the combination medicine.

For alfacalcidol
• 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.

For calcifediol
• 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 up to 2 years of age—20 to 50 mcg a day.
    • Children 2 to 10 years of age—50 mcg a day.

For calcitriol
• 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 and solution):
    • Adults, teenagers, and children—At first, 0.25 micrograms (mcg) a day. Your doctor may change your dose if needed.
  • For injection dosage form:
    • 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.

For dihydrotachysterol
• 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.

For doxercalciferol
• 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.

For ergocalciferol
• For oral dosage forms (capsules, tablets, oral solution):
  • 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 the U.S.
    • 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.
    For Canada
    • 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.

For paricalcitol
• To treat an overactive parathyroid gland in patients with kidney failure:
  • For injection dosage form:
    • 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.

Missed dose—

• For use as a dietary supplement: If you miss taking a dietary supplement for one or more days there is no cause for concern, since it takes some time for your body to become seriously low in vitamins. However, if your health care professional has recommended that you take this dietary supplement, try to remember to take it as directed every day.
• If you are taking this medicine for a reason other than as a dietary supplement and you miss a dose and your dosing schedule is:
  • One dose every other day: Take the missed dose as soon as possible if you remember it on the day it should be taken. However, if you do not remember the missed dose until the next day, take it at that time. Then skip a day and start your dosing schedule again. Do not double doses.
  • One dose a day: Take the missed dose as soon as possible. Then go back to your regular dosing schedule. However, if you do not remember the missed dose until the next day, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
  • More than one dose a day: Take the missed dose as soon as possible. Then go back to your regular dosing schedule. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

If you have any questions about this, check with your health care professional.

Storage—

To store this dietary supplement:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the dietary supplement to break down.
• Keep the oral liquid form of the dietary supplement from freezing.
• Do not keep outdated dietary supplements or those no longer needed. Be sure that any discarded dietary supplement is out of the reach of children.

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.
• Remember that the total amount of vitamin D you get every day includes what you get from foods that you eat and what you take as a supplement.

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.

Along with its needed effects, a dietary supplement may cause some unwanted effects. Alfacalcidol, calcifediol, calcitriol, dihydrotachysterol, and ergocalciferol do not usually cause any side effects when taken as directed. However, taking large amounts over a period of time may cause some unwanted effects that can be serious.

Check with your doctor immediately if any of the following effects occur:

• Late symptoms of severe overdose
  • High blood pressure;  high fever;  irregular heartbeat;  stomach pain (severe)  
  
  

Check with your health care professional as soon as possible if any of the following effects occur:

• Early symptoms of overdose
  • Bone pain;  constipation (especially in children or adolescents);  diarrhea;  drowsiness;  dryness of mouth;  headache (continuing);  increased thirst ;  increase in frequency of urination, especially at night, or in amount of urine;  irregular heartbeat ;  itching skin;  loss of appetite;  metallic taste;  muscle pain;  nausea or vomiting (especially in children or adolescents);  unusual tiredness or weakness 
  
  

• Late symptoms of overdose
  • Bone pain;  calcium deposits (hard lumps) in tissues outside of the bone;  cloudy urine;  drowsiness;  increased sensitivity of eyes to light or irritation of eyes;  itching of skin ;  loss of appetite;  loss of sex drive;  mood or mental changes;  muscle pain;  nausea or vomiting;  protein in the urine;  redness or discharge of the eye, eyelid, or lining of the eyelid;  runny nose;  weight loss 
  
  

Other side effects not listed above may also occur in some individuals. If you notice any other effects, check with your health care professional.