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Vitamin Supplement

Colecalciferol (Vitamin D3)

Brand names: Fultium-D3, Desunin, InVita D3, Thorens

Colecalciferol (vitamin D3) is a fat-soluble vitamin and prohormone supplement used in older people to prevent and treat vitamin D deficiency and, with calcium, to reduce fracture and falls risk.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It is hydroxylated in the liver and kidney to calcitriol, the active form, which enhances intestinal calcium and phosphate absorption and supports bone mineralisation and neuromuscular function.

Prescribing in practice

  • Correct established deficiency with a treatment regimen before maintenance, and ensure adequate calcium intake; co-prescribe calcium where dietary intake is low, as in many frail older people.
  • Use with caution in conditions associated with hypercalcaemia, such as sarcoidosis, primary hyperparathyroidism and some malignancies.
  • Many fixed-dose products combine colecalciferol with calcium, so review for duplication when patients take separate supplements.

Monitoring

Check serum calcium where deficiency is being treated, in renal impairment, or if hypercalcaemia is suspected; routine monitoring of asymptomatic patients on maintenance doses is not generally required.

Counselling the patient

  • Take regularly as prescribed to maintain bone health and reduce falls and fracture risk.
  • Report symptoms of high calcium such as nausea, thirst, constipation or confusion.
  • Combining with adequate calcium and weight-bearing activity helps protect bone.

Evidence & guidelines

NICE and UK osteoporosis guidance support combined calcium and vitamin D supplementation for fracture prevention in older people at risk of deficiency.

Reference: NICE NG187; PHE vitamin D guidance 2016; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

Pathways