Vitamin D and Related Compounds (Oral, Parenteral)

All humans young and old require Vitamin D in their diet, and this is easily obtained through some of the foods we eat, as well as through exposure to natural sunlight.


Despite its name, vitamin D is not actually considered a true vitamin, because vitamins are substances which cannot be manufactured by the body, and must be consumed from outside sources in order to achieve benefits from them. Vitamin D, however, can be made by the body, when exposed to sunlight, and is later converted into a usable form by the body. It is, therefore, more properly categorized as a 'pro-hormone', although for purposes of this discussion, it will retain its traditional naming convention.

Vitamins are compounds which are necessary for good health and continued human growth, and should, therefore, be a part of everyone's daily diet. Vitamin D is a compound which promotes the formation and maintenance of strong bones and strong teeth, so it's one of the most vitally important vitamins which people should include as part of their daily requirements.

People who don't get adequate vitamin D in their diets can develop a medical condition called rickets, where either strong teeth, strong bones, or both are lacking. Rickets is more prevalent in children than in adults, but adults are more subject to a condition called osteomalacia, where a whole slew of problems can develop, stemming from bone weakness. When either youngsters or adults develop these kinds of problems, doctors will commonly prescribe vitamin D as at least one form of treatment.

There are also other conditions which heighten the need for additional vitamin D in your diet, including pancreatic disease, stomach removal, hyperactive parathyroid glands, intestinal diseases, kidney disease, liver disease, and alcoholism. Some people who do not absorb sufficient vitamin D through their skin when exposed to sunshine also require extra amounts of vitamin D, and these can include people who are dark-skinned, infants who spend little time outdoors, and shut-ins who spend most of their time inside.

Some claims have been made for the effectiveness of vitamin D in treating arthritis, psoriasis, nerve problems, and the prevention of nearsightedness, although these claims have not been substantially supported by scientific evidence.

The foods which vitamin D occurs naturally in are fish and fish liver oils, as well as milk which has been fortified with vitamin D. The compound is not affected by anything in the baking or cooking process, so if it is present in the food to begin with, it will still be there after meal preparation. Another important source of vitamin D is from naturally occurring sunshine, since it is actually manufactured right in your skin as you are exposed to sunlight.

You should be able to obtain all the vitamin D you need simply by eating a balanced diet which includes regular fish and milk, and spending at least two hours each week out in the sunshine. It should be kept in mind that vitamins by themselves are inadequate for providing all the nutrients your body needs for energy requirements, and that vitamins have to be supplemented by carbohydrates, proteins, minerals, and fats. In fact, all those other nutrients are necessary because vitamins by themselves don't work very well without those other nutrients being present in the body. Vitamin D for instance, cannot be absorbed into the body without having the right kinds of fats to help with absorption.

Since it is so critical that all people intake the proper amount of vitamins and other nutrients, governments around the world have established daily requirements as a guideline so that people can be sure of how much of any given nutrient they should be ingesting. This information is commonly contained on the labels of most foods so that consumers can be aware of what percentage of their daily needs are being met by the product.

On the other hand, it is not advisable to ingest excessive vitamin D or any other nutrient for that matter. Taking in an excessive amount of Vitamin D over a prolonged time frame can cause harmful effects on the body and should therefore be avoided. To be sure that you are not over-ingesting vitamin D, remember to add up the amounts of vitamin D included in any foods you eat for a given day, as well as any vitamin D supplements you are taking.

Conditions Treated

  • Vitamin deficiency
  • bone disease
  • increasing intestinal absorption of phosphate, calcium, and magnesium

Type of Medicine

  • Fat-soluble secosteroids

Side Effects

Dietary supplements such as vitamin D can produce some very desirable results in humans, but there are also certain side effects which should be looked for when taking any of them. There is no way to predict which types of side effects will occur with which kinds of supplements, because everyone's body interacts with these supplements in a slightly different manner, so there could be no side effects whatsoever in one person, and some fairly serious side effects in another.

In practically all cases, however, taking an excessive amount of dietary supplements over a prolonged period of time is very likely to cause some highly undesirable side effects, which may become very serious. You should check with your doctor immediately if you develop any of the following symptoms: high blood pressure when you had no history of it, irregular heartbeat, high fevers, and severe stomach pain or discomfort.

In the early stages of dietary supplement overdose, you may observe any of the following symptoms or any combination of them: irregular heartbeat, itchy skin, loss of appetite, nausea or vomiting, metallic aftertaste in your mouth, bone pain, constipation or diarrhea, excessive drowsiness or fatigue, persistent headaches, more or less constant thirst, much more frequent urination, primarily at night, and unusual weakness.

In the later stages of a dietary supplementoverdose, you may experience any of the following symptoms, or any combination of them: weight loss, runny nose, protein in the urine, nausea and vomiting, mood swings, changes in behavior or mental attitudes, skin itchiness, increased sensitivity to light, eye irritation, bone pain, calcium deposits in tissues away from bone, cloudy or milky urine, unusual drowsiness or fatigue, loss of appetite, loss of sexual interest, and redness of the eyes, eyelids or eye lining.


Vitamin D should be used strictly as a dietary supplement, and should not be taken in amounts greater than those recommended for daily consumption. Because it is stored in the body, vitamin D accumulates over time, and when excessive amounts build up, it can lead to poisoning and in the most extreme cases, even death.

When taking the liquid, oral form of vitamin D, it should be consumed orally whether or not it is packaged in a dropper bottle, and can also be placed on the top of cereals, or mixed with juices and other foods.

When taking vitamin D as a dietary supplement, your doctor may want you to observe special dietary restrictions, for instance ingesting extra calcium. If your doctor makes any such recommendations, be sure to follow these very closely, so as to avoid any negative results. Dosages of vitamin D will vary from patient to patient, so the amount you might be taking could well be different from an amount a friend or relative has been prescribed. Make sure to stick with the amount that your doctor recommends for you personally, because that is the dosage which is deemed best for your specific circumstances and medical conditions. Dosages will be contingent upon how strong the supplement is, as well as how many individual dosages you take each day.

When alfacalcidol is used to treat bone disease for kidney dialysis patients, the following dosages are typical:

  • oral dosage from capsules - an initial dosage of 1 µg per day is indicated, with no more than 3 µg per day to be prescribed by your doctor.
  • oral dosage from drops - 1 µg per day, up to a limit of 3 µg per day, with the possibility of dosage increases from your doctor.
  • oral dosage from solution - a starting dosage of 1 µg per day is typical, up to a maximum 3 µg per day.
  • for dosage from injection - 1 µg per day is normal, with the possibility of increased dosages recommended by your doctor, normally not to exceed 12 µg in any given week.

For alfacalcidol treatment of diseases where the body is unable to make proper usage of calcium, the following dosages are indicated:

  • oral dosage from capsules - an initial dosage of .25 µg per day as indicated, not to exceed 1 µg per day.
  • oral dosage from drops - the same .25 µg per day is indicated initially, and on a doctor's recommendation this can be increased to 1 µg per day.
  • oral dosage from solution - a starting dosage of .25 µg per day is normal, with no more than 1 µg per day recommended as increases by your doctor.

When calcifediol is used to treat diseases of the bones which kidney dialysis patients may contract:

  • oral dosage in the form of capsules - for all children over the age of 10, teenagers, and adults, an initial dosage of 300 to 350 µg per week should be taken in equally divided dosages daily or on alternate days, with any changes decided by your doctor. For children from 2 to 10 years of age, only 50 µg is recommended, and for children two years and below, between 20 and 50 µg is recommended.

When calcifediol is used for the treatment of diseases where calcium is improperly absorbed and used by the body:

  • oral dosage in either solution form or capsules - all adults, teenagers, and children should have a recommended amount of .25 µg per day, subject to doctor revision.
  • for dosage by injection - an initial dosage of .5 µg should be injected three times a week directly into a vein.

When dihydrotachysterol is used for the treatment of diseases where calcium is not properly absorbed by the body:

  • oral dosage from tablets, solution, or capsules - adults and teenagers should be given an initial dosage of 100 µg, up to a total of 2.5 mg daily, and children should be prescribed between 1 and 5 mg per day, at doctor's discretion.

When doxercalciferol is used for the treatment of a hyperactive parathyroid in patients who have experienced kidney failure:

  • oral dosage from capsules - adults should be administered 10 µg at each dosage, three times per week at the same time as dialysis. Usage by children should be left up to doctor's discretion.

When ergocalciferol is used to prevent vitamin D deficiency:

  • oral dosage from capsules - adults and teenagers are recommended to take 5 to 10 µg per day, children between 4 and 10 should take 10 µg per day, children up to 3 years of age should take 7.5 to 10 µg per day, and pregnant or breastfeeding females should take 10 µg per day.

When ergocalciferol is used for the treatment of vitamin D deficiency:

  • adults, teenagers, and children - the amount prescribed will be entirely dependent on doctor's recommendation for the severity of deficiency experienced by an individual.

When ergocalciferol is used for the treatment of diseases in which phosphate and calcium are improperly absorbed and used by the body:

  • adults and teenagers - an initial dosage of 1,000 up to 500,000 units per day may be prescribed by your doctor.
  • children - an initial dosage of 1,000 to 200,000 units per day may be prescribed by your doctor, subject to change.

When paricalcitol is used to treat a hyperactive parathyroid for kidney failure patients:

  • oral dosage from capsules - adults should be prescribed between 1 and 2 µg once per day or 2 to 4 µg three times weekly, although this should not exceed an every other day rotation. Child usage and dosage must be decided at the discretion of the family doctor.
  • dosage by injection - adults should have .04 to .1 µg during dialysis, not to exceed an every other day basis. Usage and dosage by children must be determined at the discretion of the family doctor.

When you miss a recommended dosage of a prescribed dietary supplement, it's best to contact your doctor for specific instructions relating to your circumstances. Generally speaking, however, if you should miss taking a dietary supplement for a day or two, there is no real danger involved because your body does not reach a deficient state for several days. If you are taking vitamins for some reason besides their value as dietary supplements, and you should miss one or more dosages, you should react as follows:

  • If taking one dose every other day - if you remember about taking your missed dosage on the same day, take it then. If you don't remember a missed dosage until the next day, do not double up, but just wait and take your normally scheduled dosage on that next day.
  • If taking one dose daily - as soon as possible, you should take the dosage which you have missed, and resume your normal dosage schedule immediately afterward. If you don't remember the dosage until the next day, then skip the one which you forgot, and resume a normal schedule on the next day.
  • If taking multiple doses daily - if you remember missing a dosage on the same day, take it as soon as possible after missing the regularly scheduled time. If your missed dosage happens to come up on the time for the next regularly scheduled dosage, just skip the missed one and take the regularly scheduled dosage, and then resume your normal schedule.


Some pairings of medication should not be taken concurrently under any circumstances, while other pairings may be consumed at the same time under a doctor's supervision, and in recommended amounts. In these situations, it's fairly common for a physician to lower normally prescribed medication amounts to avoid negative interactions between the two medications.

There are a number of medications which should be carefully monitored when you are taking dietary supplements because there's a potential for interaction between the two. The list below is fairly comprehensive in identifying many of the medications which should be avoided when you're taking dietary supplements. Make sure your doctor is aware that you are taking any of these medications, so that safe amounts can be administered while you are concurrently ingesting dietary supplements.

  • Rufinamide
  • Saquinavir
  • Clarithromycin
  • Ethotoin
  • Ezogabine
  • Telithromycin
  • Phenytoin
  • Tiagabine
  • Boceprevir
  • Brivaracetam
  • Carbamazepine
  • Idelalisib
  • Lacosamide
  • Lorazepam
  • Nelfinavir
  • Oxcarbazepine
  • Clonazepam
  • Clorazepate
  • Cobicistat
  • Perampanel
  • Phenobarbital
  • Conivaptan
  • Diazepam
  • Eslicarbazepine Acetate
  • Posaconazole
  • Pregabalin
  • Clobazam
  • Ethosuximide
  • Felbamate
  • Primidone
  • Indinavir
  • Ritonavir
  • Lamotrigine
  • Stiripentol
  • Methsuximide
  • Midazolam
  • Nefazodone
  • Tellaprevir
  • Topiramate
  • Fosphenytoin
  • Gabapentin
  • Valproic Acid
  • Vigabatrin
  • Itraconazole
  • Ketoconazole
  • Voriconazole
  • Levetiracetam
  • Lopinavir
  • Zonisamide

Some medications should be avoided anywhere in the vicinity of mealtimes since there could be potential interactions between foods ingested and those medications. Consuming alcohol or smoking tobacco can also cause harmful interactions with certain medications. If you have any doubt whatsoever about the types of foods you eat, or about smoking or drinking alcohol, while you are using certain medications, make sure to bring this to the attention of your family doctor for discussion.

Some dietary supplements should also be avoided when you have medical conditions such as heart or blood vessel disease, kidney disease, or sarcoidosis. If you have any of these medical conditions, be sure to consult with your doctor about which dietary supplements should be avoided, and which are safe for ingestion.

Aluminum is one of the minerals which has a noticeable interaction with vitamin D, and aluminum can be found in most over-the-counter antacids. This could be a problem for people with kidney disease, and to avoid any negative interactions, it's best to take vitamin D either two hours prior to taking your antacids, or four hours afterward.

Calcipotriene is a drug which is very similar to vitamin D, and if taken in tandem with vitamin D any side effects may be multiplied, so it's best to avoid taking vitamin D in conjunction with calcipotriene. Digoxin is a drug which increases and strengthens the heartbeat, and since vitamin D helps your body absorb calcium which can also affect your heart, when these two are taken together, it can lead to an irregular heartbeat. For this reason, you should consult your doctor about taking vitamin D if you are also taking digoxin.

Diltiazem has a similar effect on the heart, and will, therefore, have the same risk of interaction with vitamin D, so taking these two drugs simultaneously should be something you discuss with your physician. Verapamil can also affect the heart, so if you're taking vitamin D, there exists the potential for interaction between your dietary supplement and verapamil.

Some water pills (diuretics) interact with vitamin D because they serve to increase the amount of calcium in the body, and if large amounts of vitamin D are being consumed at the same time, it could trigger an excess of calcium to be stored in the body. When the body has excess calcium, it can cause serious side effects like kidney problems.

In the category of minor interactions with vitamin D, we have drugs such as cimetidine, which decreases the body's efficiency with changing vitamin D into its usable state. This can not only decrease the potency and effectiveness of vitamin D, it may even render it unusable.

Heparin is a blood thinner which inhibits the action of clotting in the body, and can also increase the risk of broken bones when used for an extended period of time. It is therefore advisable to closely monitor the dosage of heparin, as well as its long-term usage, unless steps are taken to counteract that usage by maintaining a diet rich in vitamin D and extra calcium.

The same is true for heparin's cousin, a medication called low molecular weight heparin, which can similarly increase the risk of broken bones when used over long periods of time. The same precautions should be used with low molecular weight heparins as with ordinary heparins, i.e. make sure to follow a diet rich in calcium and vitamin D, or closely monitor the dosage and duration of usage for low molecular weight heparins.


There are certain warnings and precautions which should be observed when taking vitamin D as a supplement, without the direct supervision or recommendation of your family physician. When talking with your doctor, make sure he/she is aware of any allergies which you may have to vitamins or other compounds, and if you've ever had allergic reactions to food preservatives, dyes, or animals. If you're purchasing supplements which include vitamin D, make sure to read the package ingredients to find out if there are any substances included which you're allergic to.

No problems related to the ingestion of vitamin D have been reported among youngsters, as long as the intake of vitamin D has not exceeded recommended amounts for their age group. Youngsters who are being breastfed exclusively, and receive very little exposure to sunlight, are often at risk for taking in too little vitamin D, especially for infants of dark skin. In these cases, your family doctor can prescribe a vitamin D supplement, which will be in carefully controlled amounts. Excess intake of vitamin D in infants over a prolonged period of time may lead to stunted growth and other developmental problems.

Seniors typically have lower amounts of vitamin D in their bloodstream than do younger people, and for this reason, they should be more conscientious about including the proper amount of vitamin D in their daily diet. No problems have been reported for geriatric consumers of vitamin D, as long as the amounts taken are in line with recommended daily values.

Women who are pregnant or who are planning to become pregnant should make a special effort to take in the recommended amount of vitamin D for their particular age group and circumstances. It's also very important that the proper level of vitamin D is maintained entirely throughout the pregnancy and afterward, since the normal growth and development of an infant requires that proper levels of vitamin D be present in the mother's body for good bone formation.

Women who have very little exposure to sunlight, don't drink vitamin D-fortified milk, and do not eat fish, should make every effort to take in daily supplements including vitamin D, so that they have the proper levels in their body throughout pregnancy.

There's another aspect to vitamin D ingestion which should be observed just as conscientiously, and that's over-consumption. With too much vitamin D in mother's bloodstream, it's possible for an infant to be excessively sensitive to the effects of the vitamin, and for problems to be triggered with the parathyroid gland which, in turn, can cause potential defects in a baby's heart.

All vitamins and nutrients that a mother takes in during pregnancy will be passed on through breastfeeding, so this is the reason why proper levels of all vitamins should be carefully monitored. To be sure of having the proper amount of vitamin D in breastfed infants, it is best to follow the recommendations of your family doctor, and stick very close to those recommended amounts.


All dietary supplements, as well as other medications, should be kept well out of the reach of curious children. You should also avoid putting your supplements and medications in daily or weekly pill reminder cases because very few of these have any kind of safety features which prevent access by children.

Supplements and medication should be stored at room temperature in a tightly sealed container which cannot be accessed by children or pets and should be stored in a location away from direct light, heat, freezing temperatures, or excessive humidity. Any medicine or dietary supplements which have exceeded their expiration dates should be discarded, and if you're not sure about the proper disposal method, you should consult with your family doctor for advice.


Vitamin D is extremely important for overall good health, strong teeth, and strong bones, as well as ensuring that your immune system is up to snuff for fighting infections, and that your heart, lungs, brain, and muscles all work in coordination.

You can obtain vitamin D as a dietary supplement from external sources, but your body can also make its own vitamin D when you are exposed to sunlight for a sufficient amount of time. Although the vitamin D absorbed from sunlight must be modified before it can be effectively used by the body, once that modification occurs, the vitamin D can be used to manage calcium in your blood and bones and to help the cells throughout your entire body communicate as they should.

Ongoing research has confirmed that vitamin D is very important for the prevention and treatment of a great many serious long-term health issues. Vitamin D is the only vitamin which can be manufactured by the body, which makes it unique among all other vitamins, as it converts the vitamin D into a hormone which is often considered to be 'activated vitamin D' (medical name calcitriol).

One of the most important roles served by vitamin D is that of strengthening the bones of the body. Even if you do take in sufficient amounts of calcium and phosphorus, which are essential for the development and growth of bones, they can't be absorbed unless there is a sufficient quantity of vitamin D present in your body. That means it simply isn't enough to eat foods containing plenty of calcium and phosphorus because the body can't absorb them without the vitamin D.

Recent research has attributed even more health benefits to proper amounts of vitamin D in the body; for instance, the protection of the body's immune system, proper cardiovascular function, brain development, functionality of muscles, respiratory processes, and even anti-cancer effects.

When your body lacks sufficient quantities of vitamin D, it can lead to all sorts of medical problems such as asthma, type II diabetes, depression, high blood pressure, Alzheimer's disease, and various autoimmune diseases like multiple sclerosis, Crohn's disease, and type I diabetes.

From the above, it should be easy to see that the human body requires adequate amounts of vitamin D for proper growth, development, and ongoing good health. Without adequate amounts of vitamin D, the human body can undergo negative impacts which range from minor health issues, all the way up to degradation of the immune system, and even an increased susceptibility to cancer and other serious diseases.

Last Reviewed:
December 24, 2017
Last Updated:
April 27, 2018
Content Source: