Vitamin Supplement Pregnancy: Should not be used during pregnancy unless the clinical condition of the woman requires treatment with colecalciferol, at a dose necessary to overcome the deficiency; women should follow the advice of their practitioner as requirements vary with severity and response. Vitamin D overdose in pregnancy causes physical and mental disability and congenital heart and eye conditions due to hypercalcaemia. Colecalciferol and its metabolites are excreted in breast milk; overdose in infants induced by nursing mothers has not been observed, but allowance for the maternal dose should be made when prescribing vitamin D to a breast-fed child.

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.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Treatment of vitamin D deficiency: 1000-4000 IU (1-4 x 1000 IU capsules) daily for 10 weeks, depending on the severity of the disease and the patient response, followed by maintenance therapy of 1000-2000 IU (1-2 capsules) daily. Prevention of vitamin D deficiency or treatment of vitamin D insufficiency: 1000-2000 IU (1-2 capsules) daily. As an adjunct to specific therapy for osteoporosis: 1000 IU (1 capsule) daily.

Route: Oral - the capsule should be swallowed whole with water, preferably with the main meal of the day

Frequency: Once daily

NO ELDERLY-SPECIFIC POSOLOGY is stated in this SPC. It does list populations at high risk of vitamin D deficiency who may require higher doses and monitoring of serum 25(OH)D, several of which are relevant to older people: institutionalised or hospitalised individuals; dark-skinned individuals; individuals with limited effective sun exposure due to protective clothing or consistent sunscreen use; patients being evaluated for osteoporosis; obese individuals; users of certain concomitant medications (e.g. anticonvulsants, glucocorticoids, anti-retrovirals); those recently treated for vitamin D deficiency and requiring maintenance therapy; patients with liver or renal disease; and patients with malabsorption, including inflammatory bowel disease and coeliac disease. MONITORING: follow-up serum 25(OH)D measurements should be made approximately three to four months after initiating maintenance therapy to confirm the target level has been achieved; medical supervision is required whilst on treatment to prevent hypercalcaemia. Allowance should be made for vitamin D from supplements, other vitamin D containing medicines and other sources, and the need for additional calcium supplementation should be considered for individual patients (calcium supplements under close medical supervision). ADOLESCENTS OVER 12 YEARS: treatment of vitamin D deficiency or insufficiency - 1 capsule (1000 IU) daily depending on severity and response, given only under medical supervision. NOT RECOMMENDED for infants and children under 12 years. This SPC is for a 1000 IU capsule product; it does not describe high-dose loading regimens or combination calcium/vitamin D products.

Dose adjustments

Renal

Contraindicated in severe renal impairment (section 4.3). Use with caution in patients with impaired renal function, monitoring the effect on calcium and phosphate levels and taking account of the risk of soft tissue calcification; in severe renal insufficiency colecalciferol is not metabolised normally and other forms of vitamin D should be used. Should not be taken by patients with a tendency to form calcium-containing renal calculi. It is recommended to reduce the dose or interrupt treatment if urinary calcium exceeds 7.5 mmol/24 hours (300 mg/24 hours).

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to colecalciferol or to any of the excipients
Hypercalcaemia and/or hypercalciuria
Nephrolithiasis (renal calculi)
Hypervitaminosis
Severe renal impairment

Side effects

Hypercalcaemia (uncommon)
Hypercalciuria (uncommon)
Pruritus (rare)
Rash (rare)
Urticaria (rare)

Interactions

Cardiac glycosides including digitalis - patients may be susceptible to high calcium levels; monitor ECG parameters and calcium levels; caution is required in patients being treated for cardiovascular disease
Thiazide diuretics (benzothiadiazine derivatives) - increase the risk of hypercalcaemia by decreasing urinary calcium excretion; monitor plasma and urine calcium during long-term treatment
Anticonvulsants (phenytoin, phenobarbital, primidone) - may diminish the effect of colecalciferol through hepatic enzyme induction
Rifampicin - may reduce effectiveness through hepatic enzyme induction; isoniazid may reduce effectiveness by inhibiting metabolic activation of colecalciferol
Drugs causing fat malabsorption (orlistat, liquid paraffin, cholestyramine) - may impair absorption of colecalciferol
Actinomycin and imidazole antifungal agents - interfere with vitamin D activity by inhibiting its conversion
Metabolites or analogues of vitamin D - careful monitoring of serum calcium is recommended if combined
Phosphate infusions should not be administered to lower hypercalcaemia of hypervitaminosis D because of the danger of metastatic calcification

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. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Pathways