Cholecalciferol — NZ Medication Guide

What is Cholecalciferol?

Cholecalciferol (generic name: cholecalciferol (vitamin D3)) is a medication used primarily for vitamin D deficiency treatment and prevention, bone health, and fall/fracture prevention. Cholecalciferol supplements are widely available OTC in New Zealand pharmacies without a prescription. High-dose prescription formulations (e.g., Stoss therapy with 1.25mg capsules) are funded by Pharmac for confirmed deficiency.

What is Cholecalciferol Used For?

Cholecalciferol is prescribed by healthcare professionals in New Zealand for the following indications:

• Vitamin D deficiency (proven by blood test)
• Prevention of vitamin D deficiency in high-risk groups (elderly, dark skin, limited sun exposure)
• Osteomalacia (softening of bones due to vitamin D deficiency)
• Rickets in children
• Secondary hyperparathyroidism due to vitamin D deficiency
• Adjunct to calcium for osteoporosis prevention and treatment
• Fall prevention in elderly patients with low vitamin D

How Does Cholecalciferol Work?

Cholecalciferol (vitamin D3) is converted in the liver to 25-hydroxyvitamin D (calcidiol) and then in the kidneys to the active form 1,25-dihydroxyvitamin D (calcitriol). Active vitamin D promotes intestinal absorption of calcium and phosphate, supports bone mineralisation, regulates parathyroid hormone (PTH) secretion, and plays important roles in immune function, muscle strength, and cell growth. Deficiency causes reduced calcium absorption, elevated PTH, and impaired bone formation.

How to Take Cholecalciferol

For deficiency treatment: doses depend on severity and the prescriber’s guidance — commonly 1.25mg (50,000 IU) weekly for 6–8 weeks, then maintenance. For prevention: 25 micrograms (1,000 IU) daily is commonly recommended for at-risk groups. Vitamin D3 supplements are better absorbed when taken with a fatty meal as it is fat-soluble. Supplements are available over-the-counter in NZ pharmacies without a prescription.

Common Side Effects

• Generally very well tolerated at recommended doses
• Nausea or constipation with high doses
• Metallic taste with very high doses
• Hypercalcaemia symptoms with toxicity (excess dosing) — see serious effects

Serious Side Effects — Seek Medical Attention

• Hypercalcaemia (vitamin D toxicity with excessive doses) — nausea, weakness, confusion, excessive thirst, kidney stones
• Hypercalciuria — calcium deposits in kidneys
• Renal impairment with prolonged toxicity
• Toxicity typically only occurs with very high supplemental doses (over 10,000 IU daily for extended periods)

Drug Interactions

• Thiazide diuretics — increase risk of hypercalcaemia when combined with vitamin D
• Digoxin — hypercalcaemia from excess vitamin D increases digoxin toxicity risk
• Orlistat (weight loss medication) — reduces absorption of fat-soluble vitamins including vitamin D
• Cholestyramine — reduces vitamin D absorption
• Corticosteroids — chronic use impairs vitamin D metabolism

New Zealand Prescribing Information

Vitamin D deficiency is common in New Zealand, particularly in the South Island, among people with dark skin, the elderly, those who cover their skin for cultural or religious reasons, and those with limited sun exposure. BPAC NZ provides detailed guidance on vitamin D testing and supplementation. Routine testing is not recommended for the general population — supplementation without testing is appropriate for high-risk groups. Serum 25-hydroxyvitamin D levels below 50 nmol/L are considered deficient in NZ guidelines. The recommended dietary intake from supplements is 400–1,000 IU (10–25 micrograms) daily for adults at risk.

Frequently Asked Questions

How do I know if I need vitamin D supplements?

Vitamin D deficiency is common in NZ but routine testing is not recommended for everyone. High-risk groups who may benefit from supplementation without testing include: people with limited sun exposure, people with dark skin, those who cover their skin, the elderly, and people with malabsorption conditions. If you have symptoms such as bone pain, muscle weakness, or fatigue, a blood test (serum 25-hydroxyvitamin D) can confirm deficiency. Speak to your doctor or pharmacist about whether supplementation is appropriate for you.

Can I get too much vitamin D from supplements?

Vitamin D toxicity from sun exposure is not possible. However, excessive supplement doses over extended periods can cause hypercalcaemia (high blood calcium), leading to nausea, weakness, kidney stones, and confusion. Toxicity generally requires daily doses above 10,000 IU (250 micrograms) for extended periods. Standard supplementation of 1,000 IU (25 micrograms) daily is safe for most adults.

References & Further Information

The following New Zealand and international resources were used to inform this page:

• New Zealand Formulary — Cholecalciferol
• Pharmac — Funded Medicines Schedule
• BPAC NZ — Vitamin D: Testing and Treatment
• Ministry of Health NZ — Vitamin D Guidelines

Reviewed by a Registered Pharmacist — KiwiMeds New Zealand