[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Vitamins](https://durgical.com/en/pharmacology/classes/vitamins/) › Colecalciferol

# Colecalciferol

## Vitamins?

Vitamins

Vitamin D3, the form the skin makes in sunlight. Liver and kidney turn it into the hormone that lets the gut absorb calcium.

Updated Nov 1, 2026

Also called: cholecalciferol, vitamin D3

## Quick facts

**Group**
[Vitamins](https://durgical.com/en/pharmacology/classes/vitamins/)

**Target**
Vitamin D receptor (VDR), a nuclear receptor

**Used for**
Prevention and treatment

**Key effects**
Usually none at normal amounts · With excess

**Monitor**
Signs of hypercalcaemia

**ATC**
A11CC05

No doses: the clinician sets them by the current guideline.

On this page

- The basics Mechanism of action
- Indications
- Adverse effects
- Pharmacokinetics
- Memory aid

- Safety Contraindications
- Key interactions
- What is monitored
- Pregnancy and breastfeeding
- Nursing care

- Study Test yourself

- Connections Connections

## Mechanism of action

◎**Vitamin D receptor (VDR), a nuclear receptor**Colecalciferol

ⓘ The figure shows calcitriol, the active hormone made from colecalciferol in the liver and kidney, bound to the ligand-binding domain of the human vitamin D receptor.

**Target in 3D:** Vitamin D receptor (VDR), a nuclear receptor. PDB structure 1DB1 (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/1DB1) · Drag to rotate · pinch to zoom

Colecalciferol is a prohormone. The liver adds a hydroxyl group (25-hydroxyvitamin D, the form measured in blood) and the kidney adds a second one, making calcitriol. Calcitriol binds the vitamin D receptor and switches on genes that increase calcium and phosphate absorption in the gut, help mineralise bone and restrain parathyroid hormone.

- Skin (sunlight) or diet supplies vitamin D3
- Liver: 25-hydroxylation; kidney: 1α-hydroxylation to calcitriol
- Calcitriol binds the vitamin D receptor
- More calcium and phosphate absorbed; bone mineralises

## Indications

- Prevention and treatment of vitamin D deficiency, including rickets and osteomalacia [Rickets and osteomalacia →](https://durgical.com/en/conditions/rickets-and-osteomalacia/)
- Vitamin D deficiency in people with, or at risk of, osteoporosis [Osteoporosis →](https://durgical.com/en/conditions/osteoporosis/)

## Adverse effects

### Common

- Usually none at normal amounts
- With excess: nausea, vomiting, weakness, loss of appetite, constipation

### Serious (rare, important)

- High blood calcium (hypercalcaemia): weakness, nausea, vomiting, constipation, thirst, frequent urination, confusion
- Kidney stones and kidney damage
- Calcium deposits in the heart, blood vessels and lungs

## Contraindications

- Hypercalcaemia
- Vitamin D toxicity (hypervitaminosis D)

## Key interactions

**Mineral oil**
Reduces absorption of vitamin D and other fat-soluble vitamins

**Thiazide diuretics**
Can cause hypercalcaemia, especially in hypoparathyroidism

**Other vitamin D products, fortified foods and calcium supplements**
Total intake adds up; risk of toxicity

## What is monitored

- Blood calcium when high amounts are used or kidney function is reduced
- Signs of hypercalcaemia

## Pregnancy and breastfeeding

Needed in pregnancy; amounts above the recommended intake are avoided unless prescribed, because excess vitamin D harmed the fetus in animal studies.

## Nursing care

- Ask about all sources of vitamin D: fortified foods, multivitamins and prescriptions.
- Teach the signs of too much vitamin D: thirst, frequent urination, nausea, constipation, weakness, confusion.
- Identify people at risk of deficiency: little sun exposure, darker skin, malabsorption, older age.

## Pharmacokinetics

**Absorption**
Fat-soluble; absorbed from the gut with dietary fat; mineral oil reduces absorption

**Metabolism**
Activated in two steps, first in the liver, then in the kidney

**Onset and duration**
Delayed, because the active hormone must first be made

## Memory aid

«Sun → skin → liver (25) → kidney (1) → gut»: vitamin D3 needs two stops before it can pull calcium in.

## Test yourself

Think of the answer, then tap the question to see it.

## Where is colecalciferol activated?

First in the liver (25-hydroxylation), then in the kidney (1α-hydroxylation) to calcitriol.

## Which bone diseases follow vitamin D deficiency in children and adults?

Rickets in children, osteomalacia in adults.

## What lab abnormality explains the symptoms of vitamin D toxicity?

Hypercalcaemia.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/colecalciferol/)

[More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology)

## Connections

## Related drugs 3

- [Ergocalciferol](https://durgical.com/en/pharmacology/ergocalciferol/)
- [Calcitriol](https://durgical.com/en/pharmacology/calcitriol/)
- [Calcium carbonate](https://durgical.com/en/pharmacology/calcium-carbonate/)

## Related conditions 2

- [Rickets and osteomalacia](https://durgical.com/en/conditions/rickets-and-osteomalacia/)
- [Osteoporosis](https://durgical.com/en/conditions/osteoporosis/)

[← Back to the class: Vitamins](https://durgical.com/en/pharmacology/classes/vitamins/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Vitamin D: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/002405.htm) (MedlinePlus (U.S. National Library of Medicine), 2026); [DailyMed - ERGOCALCIFEROL capsule](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=87e80b1f-e376-45ba-825b-a6fda4b82325) (DailyMed (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=A11CC05) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); [RCSB PDB - 1DB1: CRYSTAL STRUCTURE OF THE NUCLEAR RECEPTOR FOR VITAMIN D COMPLEXED TO VITAMIN D](https://www.rcsb.org/structure/1DB1) (RCSB Protein Data Bank, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/pharmacology/colecalciferol/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/colecalciferol/