cholecalciferol (generic name)
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SafetyDISCLAIMER: Many complementary techniques are practiced by healthcare professionals with formal training, in accordance with the standards of national organizations. However, this is not universally the case, and adverse effects are possible. Due to limited research, in some cases only limited safety information is available.
Avoid or use caution with known hypersensitivity to vitamin D or any of its analogues and derivatives.
Side Effects and Warnings
Vitamin D is generally well tolerated in recommended "Adequate Intake (AI)" doses. One study found a greater likelihood of daytime sleepiness for patients given vitamin D analogues.
Vitamin D toxicity can result from regular excess intake of this vitamin, and may lead to hypercalcemia and excess bone loss. Individuals at particular risk include those with hyperparathyroidism, kidney disease, sarcoidosis, tuberculosis, or histoplasmosis. Chronic hypercalcemia may lead to serious or even life-threatening complications, and should be managed by a physician. Early symptoms of hypercalcemia may include nausea, vomiting, and anorexia (appetite/weight loss), followed by polyuria (excess urination), polydipsia (excess thirst), weakness, fatigue, somnolence, headache, dry mouth, metallic taste, vertigo, tinnitus (ear ringing), and ataxia (unsteadiness). Kidney function may become impaired, and metastatic calcifications (calcium deposition in organs throughout the body) may occur, particularly affecting the kidneys. Treatment involves stopping the intake of vitamin D or calcium, and lowering the calcium levels under strict medical supervision, with frequent monitoring of calcium levels. Acidification of urine and corticosteroids may be necessary.
Pregnancy and Breastfeeding
The recommended adequate intake for pregnant women is the same as for non-pregnant adults. Some authors have suggested that requirements during pregnancy may be greater than these amounts, particularly in sun-deprived individuals, although this has not been clearly established. Due to risks of vitamin D toxicity, any consideration of higher daily doses of vitamin D should be discussed with a physician.
Vitamin D is typically low in maternal milk, and to prevent deficiency and rickets in exclusively breastfed infants, supplementation may be necessary, starting within the first two months of life.
Interactions with Drugs
Decreased vitamin D effects may occur with the use of certain anti-seizure drugs, as they may induce hepatic microsomal enzymes and accelerate the conversion of vitamin D to inactive metabolites.
Based on mechanism of action, use of vitamin D and calcium together may alter inflammatory response.
Intestinal absorption of vitamin D may be impaired with the use of these agents. Patients on cholestyramine or colestipol should be advised to allow as much time as possible between the ingestion of these drugs and vitamin D.
Use of corticosteroids can cause osteoporosis and calcium depletion with long-term administration. This calcium depletion creates a greater need for both supplemental calcium and vitamin D (which is necessary for calcium absorption).
Intestinal absorption of vitamin D may be impaired with the use of mineral oil.
Rifampin increases vitamin D metabolism and reduces vitamin D blood levels. The need for vitamin D supplementation with rifampin has not been thoroughly studied, although additional supplementation may be necessary.
Stimulant laxatives can reduce dietary vitamin D absorption. Stimulant laxatives should be limited to short-term use if possible.
Concurrent administration of thiazide diuretics and vitamin D to hypoparathyroid patients may cause hypercalcemia, which may be transient or may require discontinuation of vitamin D. Examples of thiazide diuretics include chlorothiazide (Diuril®), chlorthalidone (Hygroton®, Thalitone®), hydrochlorothiazide (HCTZ®, Esidrix®, HydroDIURIL®, Ortec®, Microzide®), indapamide (Lozol®), and metolazone (Zaroxolyn®).
Interactions with Herbs and Dietary Supplements
Based on mechanism of action, the use of vitamin D and calcium together may alter inflammatory response.
Vitamin D should be used with caution in patients taking herbs with similar properties on the heart as digoxin, because hypercalcemia (which may result with excess vitamin D use) may precipitate abnormal heart rhythms.
Vitamin D is necessary for calcium absorption. Vitamin D is often included in calcium supplement products.