Cholecalciferol

Vitamins. Regulator of calcium-phosphorus metabolism

ATC code: A11CC05(Colecalciferol (vitamin D3))

Brand names – drugs: Drisdol

Brand names – supplements: Solgar Vitamin D3, NOW Foods Vitamin D-3, Thorne Vitamin DSupplements are not tested in clinical trials and are not registered as medications.

Updated 19 Aug 2026 · Methodology

Indications

Postmenopausal osteoporosis

First line

First-line and a required component of combination therapy for postmenopausal osteoporosis, always together with calcium and antiresorptive or anabolic agents (bisphosphonates, denosumab, teriparatide). and meta-analyses show that combined calcium 1,000–1,200 mg and vitamin D 800–1,000 IU daily reduces hip fracture risk by 16% in at-risk populations. Vitamin D monotherapy in patients with normal bone density does not reduce fracture risk.

Vitamin D monotherapy is not indicated for fracture prevention in pre- or postmenopausal women without osteoporosis.

Sources

ICD-10: M81.0 · ICD-11: FB83.11

Rickets in children

First line

Cornerstone treatment and prevention of rickets in children. Prophylactic dose for term newborns is 400 IU daily from the first days of life, 800–1,000 IU daily for preterm infants. Therapeutic dose for established rickets is 2,000–5,000 IU daily for 30–45 days followed by prophylactic dosing. Efficacy is supported by decades of paediatric practice and is reflected in the and Russian Paediatric Society guidelines.

In children with concomitant gastrointestinal disease (coeliac disease, cystic fibrosis, short bowel syndrome) doses are individualised with 25(OH)D monitoring.

Sources

ICD-10: E55.0 · ICD-11: 5B57.0

Vitamin D deficiency

First line

First-line therapy for correcting vitamin D deficiency and insufficiency in adults. Standard loading regimens are 50,000 IU weekly for 8 weeks or 6,000 IU daily, followed by maintenance 1,500–2,000 IU daily. Target 25(OH)D is at least 30 ng/mL per the Endocrine Society and Russian clinical guidelines. Doses are 2–3 times higher in obesity, malabsorption syndromes, and in patients on anticonvulsants.

In chronic kidney disease colecalciferol is preferred over active metabolites (alfacalcidol, calcitriol) for initial therapy. In sarcoidosis and other granulomatous diseases, only with monitoring of serum calcium.

Sources

ICD-10: E55.9 · ICD-11: 5B57

Falls prevention in older adults

Individual decision

In adults over 65 with confirmed vitamin D deficiency, 800–1,000 IU daily reduces the risk of falls in several meta-analyses. The 2018 update found the effect insufficient in patients without deficiency and withdrew the prior recommendation. The decision is individualised based on 25(OH)D level, physical activity, and other fall risk factors.

Doses above 4,000 IU daily without clinical indications are not recommended – dedicated RCTs showed a paradoxical increase in fall risk.

Sources

ICD-10: R29.6 · ICD-11: MB47.C

Autoimmune disease prevention

Individual decision

The VITAL trial (BMJ 2022) showed a 22% reduction in autoimmune disease incidence in adults 50+ after 5 years of vitamin D 2,000 IU daily. The finding comes from a single cohort, has not been reproduced in other RCTs, and the effect accrues over years. International rheumatology societies do not recommend vitamin D as primary prevention of autoimmune disease.

Sources

NEJM: Vitamin D Supplements and Prevention of Autoimmune Disease (VITAL ancillary) (2022)

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

Prophylaxis of acute respiratory infections

Not recommended

The 2021 Cochrane review (46 RCTs, more than 75,000 participants) showed a modest effect on acute respiratory infections – about 2% absolute reduction, more pronounced in patients with baseline deficiency. , , and CDC do not include vitamin D in respiratory infection prophylaxis protocols. Routine prescribing in patients without deficiency is not justified.

Vaccination and hand hygiene remain the cornerstones of respiratory infection prevention.

Sources

Cochrane: Vitamin D supplementation for prevention of acute respiratory tract infections (2021)

ICD-10: J06.9 · ICD-11: CA07.0

Anti-aging and longevity

Not recommended

Cholecalciferol (vitamin D3) is a fat-soluble vitamin. It is prescribed for prevention and treatment of vitamin D deficiency and for osteoporosis in combination with calcium (AEMPS Ficha Técnica). In anti-aging communities, vitamin D3 is taken in high doses to slow aging and extend life. The large VITAL trial (NEJM 2019, over 25,000 participants) showed no reduction in cardiovascular events or all-cause mortality on 2000 IU/day vitamin D3 versus placebo. In people with normal 25(OH)D, no clinical studies of prophylactic anti-aging use exist. Overdose causes hypercalcemia with risk of kidney dysfunction and arrhythmias. If cholecalciferol is being taken in high doses without confirmed deficiency, consider seeking a second opinion.

Sources

How to read tiers A–F

AStrong evidence – first or second line in international guidelines
BRecommended in selected cases
CStudy data contradict each other
DBenefit not proven, no documented harm
FDocumented harm, or risk without benefit

Mechanism of action

Colecalciferol (vitamin D3) is hydroxylated in the liver to 25-hydroxyvitamin D and then in the kidney to the active form 1,25-dihydroxyvitamin D (calcitriol). Calcitriol binds the nuclear vitamin D receptor and regulates intestinal calcium and phosphate absorption, renal calcium reabsorption, and bone mineralisation. It also modulates immune function, cell proliferation, and cytokine synthesis.

Safety

Contraindications

Hypercalcaemia of any aetiology
Hypervitaminosis D
Calcium-based renal stones
Active pulmonary tuberculosis
Sarcoidosis and other granulomatous diseases (only with calcium monitoring)
Severe hypercalciuria

Serious adverse effects

Hypercalcaemia with uncontrolled high-dose use
Nephrocalcinosis and renal function decline with prolonged overdose

Common adverse effects

Dry mouth
Dyspepsia at high doses

Uncommon adverse effects

Hypercalciuria
Weakness and fatigue with overdose

Pregnancy: can you take Cholecalciferol?

AEMPS summary of product characteristics (section 4.6, cholecalciferol 50,000 IU): the recommended daily intake of vitamin D in pregnancy is 400 IU; women with deficiency may need up to 2,000 IU a day. Data in pregnant women are very limited, and animal studies showed reproductive toxicity. Prolonged overdose is avoided: sustained hypercalcaemia can lead to mental and physical retardation, supravalvular aortic stenosis and retinopathy in the child. High-dose products are not recommended in pregnancy; lower-dose alternatives are used instead.

Breastfeeding: can you take Cholecalciferol?

Transfers into breast milk in small amounts. On 400–600 IU daily in the mother, the infant receives less than 10% of daily needs – breastfeeding alone does not provide a prophylactic dose, so infants are supplemented directly.

Calculate RID

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Practical notes

Timing and administration

Take with or immediately after a meal, preferably one containing fat – vitamin D is fat-soluble and absorption improves with dietary fat. Formulation matters: oil-based drops and capsules are absorbed better than aqueous emulsions in malabsorption syndromes. Time of day is not clinically important.

Monitoring

Check 25(OH)D 3 months after starting therapy. Target level 30–60 ng/mL (75–150 nmol/L). After the target is reached, retest annually. Levels above 100 ng/mL require dose reduction due to hypercalcaemia risk. Monitor serum calcium and creatinine during long-term high-dose therapy.

Food and drinks

Vitamin D interacts with several drug classes. Orlistat and cholestyramine reduce absorption – separate doses by at least 2 hours. Thiazide diuretics increase the risk of hypercalcaemia. Anticonvulsants (phenytoin, phenobarbital) accelerate vitamin D catabolism – the dose is doubled. Glucocorticoids reduce the effect – doses are adjusted by 25(OH)D level.

Special situations

In obesity (BMI above 30), effective doses are 2–3 times higher than standard because adipose tissue sequesters vitamin D. During pregnancy and lactation, prophylactic dose is 600–800 IU daily; in confirmed deficiency up to 4,000 IU daily with 25(OH)D monitoring. Infants receive prophylaxis from the first days of life regardless of feeding type.

Common myths

Myth: “all adults should take vitamin D continuously”. Fact: the recommendation applies to at-risk groups (northern latitudes, older adults, dark skin, anticonvulsants, obesity). Healthy people with normal 25(OH)D do not derive proven benefit.

Myth: “vitamin D treats everything from depression to cancer”. Fact: RCTs have not confirmed effects on cognition, depression, or cancer outcomes (VITAL, Cochrane). Only deficiency correction, rickets, and osteoporosis as adjunctive therapy are high-tier indications.

Myth: “D3 and D2 are equivalent”. Fact: D3 (colecalciferol) is more effective than D2 (ergocalciferol) per meta-analyses – it raises 25(OH)D faster and more stably.

Drug–drug interactions

3 pairs found. Sorted from critical to minor.

MajorHydrochlorothiazideThiazide diuretics

Mechanism

Thiazides reduce urinary calcium excretion: that property is exploited in calcium stone disease, but it means calcium is retained. If vitamin D simultaneously increases what comes in through the gut, the balance shifts towards hypercalcaemia. Risk rises with age, with summer dehydration and with reduced renal function.

Symptoms

Weakness, nausea, constipation, polyuria and thirst, confusion in the older patient. Moderate hypercalcaemia is easily mistaken for the diuretic's own effect or for dehydration.

Management

This is not a forbidden combination: many patients with hypertension need vitamin D. What changes is the follow-up. Measure serum calcium before starting vitamin D and at 4–8 weeks, then periodically. Avoid high vitamin D doses without a documented deficiency and watch hydration in summer. If calcium rises, adjust the supplement first, not the antihypertensive.

Sources

Pair details →Hydrochlorothiazide →

ModerateCalcium (oral salts: carbonate, citrate, lactate, gluconate)Mineral supplements. Calcium

Mechanism

Here the combination is intended: vitamin D increases intestinal calcium absorption, which is why the two are prescribed together in osteoporosis. The problem comes from excess, not deficit. With sustained high doses of both, the enhanced absorption can lead to hypercalcaemia, particularly in someone already on a thiazide diuretic or with reduced renal function.

Symptoms

Intense thirst, passing large volumes of urine, constipation, nausea, weakness, confusion. On labs, high serum calcium and, over time, kidney stones and vascular calcification.

Management

The combination at guideline doses is correct and should not be avoided. What needs watching is the unintended sum: supplement calcium plus a bone complex plus dietary calcium, with vitamin D from another bottle. Read labels to avoid duplication, and on long-term treatment monitor serum calcium and renal function. Self-directed monthly megadoses of vitamin D add nothing and increase this risk.

Sources

NIH Office of Dietary Supplements: Calcium – Health Professional Fact Sheet (2025)

Pair details →Calcium (oral salts: carbonate, citrate, lactate, gluconate) →

MinorCalcium carbonateMineral supplements. Calcium

Mechanism

Vitamin D increases intestinal calcium absorption by activating calbindin in enterocytes. The synergistic effect benefits osteoporosis and calcium deficiency.

Symptoms

On a balanced dose, no symptoms. At excessive doses of vitamin D (over 4000 IU/day chronically) and calcium (over 1500 mg/day), hypercalcaemia risk: thirst, polyuria, nausea, weakness, arrhythmia.

Management

Standard combination in osteoporosis prevention and treatment: colecalciferol 800–2000 IU/day plus calcium 1000–1200 mg/day (counting dietary calcium). Check calcium and creatinine every 6 months in patients with chronic kidney disease or prior nephrolithiasis.

Sources

FDA: Synthroid (levothyroxine sodium) prescribing information (2017)

Pair details →Calcium carbonate →

Label mentions7 mentions

Verbatim lines from the interaction sections, in the language of the label

From this drug’s label

Moderatedigitálicosclass named in the label
«En los casos de tratamiento con medicamentos digitálicos y otros glucósidos cardíacos, la administración de vitamina D 3 puede aumentar el riesgo de toxicidad digitálica (arritmia). Se necesita una…»
AEMPS, section 4.5 · Open on CIMA
ModerateDigoxin
«Se requiere precaución en pacientes que reciben tratamiento para enfermedades cardiovasculares (ver sección 4.5) como glucósidos cardíacos, incluida la digoxina.»
AEMPS, section 4.4 · Open on CIMA
Moderatediuréticosclass named in the label
«En los casos de tratamiento con diuréticos tiazídicos, que disminuyen la eliminación urinaria de calcio, se recomienda el control de la concentración sérica de calcio.»
AEMPS, section 4.5 · Open on CIMA
Moderatetiazidasclass named in the label
«En los casos de tratamiento con diuréticos tiazídicos, que disminuyen la eliminación urinaria de calcio, se recomienda el control de la concentración sérica de calcio.»
AEMPS, section 4.5 · Open on CIMA
Orlistat
«El tratamiento simultáneo con una resina de intercambio iónico como colestiramina, hidrocloruro de colestipol, orlistat o laxantes como el aceite de parafina puede reducir la absorción…»
AEMPS, section 4.5 · Open on CIMA
Phenytoin
«El uso concomitante de anticonvulsivos (como fenitoína) o barbitúricos (y posiblemente otros medicamentos que inducen enzimas hepáticas) puede reducir el efecto de la vitamina D 3 por inactivación…»
AEMPS, section 4.5 · Open on CIMA
Rifampicin
«La rifampicina puede reducir la eficacia del colecalciferol debido a la inducción de enzimas hepáticas.»
AEMPS, section 4.5 · Open on CIMA

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Frequently asked

What is Cholecalciferol used for?

Cholecalciferol is evaluated for the following indications with varying evidence strength: Postmenopausal osteoporosis (evidence tier A), Rickets in children (evidence tier A), Vitamin D deficiency (evidence tier A). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Cholecalciferol?

Common side effects of Cholecalciferol (≥ 1 in 100): Dry mouth, Dyspepsia at high doses. See the Safety section for uncommon and serious reactions.

Is Cholecalciferol safe during pregnancy?

Is Cholecalciferol compatible with breastfeeding?

Who should not take Cholecalciferol?

Cholecalciferol is contraindicated in: Hypercalcaemia of any aetiology; Hypervitaminosis D; Calcium-based renal stones; Active pulmonary tuberculosis; Sarcoidosis and other granulomatous diseases (only with calcium monitoring). Full list in the Safety section.

“all adults should take vitamin D continuously”

the recommendation applies to at-risk groups (northern latitudes, older adults, dark skin, anticonvulsants, obesity). Healthy people with normal 25(OH)D do not derive proven benefit.

“vitamin D treats everything from depression to cancer”

RCTs have not confirmed effects on cognition, depression, or cancer outcomes (VITAL, Cochrane). Only deficiency correction, rickets, and osteoporosis as adjunctive therapy are high-tier indications.

“D3 and D2 are equivalent”

D3 (colecalciferol) is more effective than D2 (ergocalciferol) per meta-analyses – it raises 25(OH)D faster and more stably.

Official sources

Direct links to regulator labels. Open in a new tab.

Other drugs in this group

Choline (umbrella: bitartrate, phosphatidylcholine, lecithin), Cordyceps (Cordyceps sinensis, Cordyceps militaris), Cranberry (Vaccinium macrocarpon), Creatine monohydrate, Lecithin (soy or sunflower phosphatidylcholine), Panax ginseng (Korean/Chinese ginseng), Saw palmetto (Serenoa repens), Zeaxanthin