Calciferol is another name for vitamin D. It is used to treat and prevent vitamin D deficiency, to support bone health, and alongside calcium in osteoporosis. In South Africa, Calciferol products are often high-strength 50,000 IU preparations that are pharmacy-scheduled and taken weekly or monthly — not daily.
What is Calciferol?
Calciferol is vitamin D. The term covers two related forms:
| Form | Also called | Source |
|---|---|---|
| Ergocalciferol | Vitamin D2 | Plant and fungal sources; older supplements |
| Cholecalciferol | Vitamin D3 | Made in skin from sunlight; animal sources |
Both raise vitamin D levels. D3 is generally regarded as more effective at raising and maintaining them, though D2 is still used and works.
Products registered under this name in South Africa include Calciferol tablets and Calciferol Oily drops at 50,000 IU, which are Schedule 3 — obtained through a pharmacist. That strength is important. 50,000 IU is a high-dose preparation intended to be taken weekly, monthly, or as a short loading course — not daily. A typical daily maintenance supplement is a few hundred to a couple of thousand IU. Taking a 50,000 IU product daily by mistake is a genuine route to vitamin D toxicity.
Read your pack and the instructions you were given, and if the frequency is unclear, ask the pharmacist before taking it.
Vitamin D is unusual among vitamins in that the body makes it. Sunlight on skin converts a cholesterol derivative into vitamin D, which the liver and then the kidneys convert into its active form. It then acts more like a hormone than a vitamin, its main jobs being to:
- Increase calcium and phosphate absorption from the gut — its central role.
- Support bone mineralisation. Without enough vitamin D, calcium cannot be used properly, however much is eaten.
- Support muscle function, including balance and fall prevention in older people.
- Contribute to immune function.
What is Calciferol commonly used for?
- Treating vitamin D deficiency, usually confirmed by a blood test.
- Preventing deficiency in people at higher risk.
- Supporting bone health, and as part of managing osteoporosis, almost always with calcium.
- Rickets in children and osteomalacia in adults — softening of bone caused by severe deficiency.
- Alongside osteoporosis medicines such as alendronic acid, which work poorly without adequate vitamin D and calcium. Some products combine the two.
- In malabsorption conditions, where fat-soluble vitamins are poorly absorbed.
- In chronic kidney disease, though specially activated forms are often needed there instead.
Vitamin D is not a general tonic. Correcting a deficiency produces real benefit; taking more once levels are adequate does not add further benefit, and beyond a point causes harm.
South Africa has abundant sunshine, which makes deficiency easy to assume away — but it remains common, particularly in people with darker skin (melanin reduces vitamin D synthesis), those who cover up, indoor workers, older adults, and people who are housebound.
Who commonly looks for Calciferol and why
- People told they have low vitamin D on a blood test.
- People with osteoporosis or osteopenia, usually prescribed it with calcium.
- Older adults, who make less vitamin D in skin and are at greater risk of falls and fractures.
- People with darker skin, who need more sun exposure for the same synthesis.
- People who are housebound, work indoors, or cover most of their skin.
- Pregnant and breastfeeding women, on professional advice.
- Breastfed infants, who are often given supplementation — always on medical advice.
- People with malabsorption, including coeliac disease, inflammatory bowel disease, or after bariatric surgery.
- People on long-term corticosteroids such as prednisone, which affect bone.
- People with muscle aches or fatigue, hoping vitamin D explains it — a group better served by a blood test than by assumption.
What to check on the label before taking Calciferol
- The strength in IU, and how often to take it. With high-strength products this is the critical pairing. 50,000 IU weekly and 50,000 IU daily are vastly different exposures.
- Whether it is D2 (ergocalciferol) or D3 (cholecalciferol).
- Whether calcium is included, or whether you need it separately.
- Whether it is a combination product — some contain an osteoporosis medicine such as alendronic acid, which has its own strict dosing instructions.
- Whether you take anything else containing vitamin D, including a multivitamin, a calcium-and-D combination or a fortified product. Totals add up quietly.
- The form — tablet, capsule or oily drops — and how drops should be measured.
- Expiry date and storage.
Vitamin D is fat-soluble, so it is better absorbed with a meal containing some fat, and it is stored in the body rather than excreted like the water-soluble vitamins. That storage is exactly why excess accumulates.
Safety, interactions and when to seek professional advice
At appropriate doses vitamin D is well tolerated. The risk is excess, and because it is stored rather than flushed out, it builds up over time.
Too much vitamin D causes hypercalcaemia — raised blood calcium. Symptoms include nausea, vomiting, poor appetite, constipation, marked thirst, frequent urination, weakness, confusion and, over time, kidney stones or kidney damage. Seek medical advice if these appear while supplementing.
This almost always results from taking high-dose products too frequently, or from stacking several supplements that each contain vitamin D — not from sunlight, which is self-limiting.
Speak to a doctor or pharmacist before starting if you:
- Have high blood calcium, or a condition causing it such as sarcoidosis, tuberculosis or an overactive parathyroid gland.
- Have kidney disease or a history of kidney stones.
- Take digoxin, where raised calcium can be dangerous.
- Take a thiazide diuretic, which reduces calcium excretion.
- Take anti-epileptic medicines, rifampicin or corticosteroids, which affect vitamin D metabolism.
- Take orlistat, cholestyramine or long-term liquid paraffin, which reduce absorption of fat-soluble vitamins.
- Are pregnant or breastfeeding.
- Are giving it to an infant or child, where dosing is weight-based and high-strength adult products are not appropriate.
- Already take another vitamin D-containing supplement.
Do not take high-strength preparations more often than directed, and do not increase the dose on the assumption that more will help faster.
See a doctor rather than self-treating if you have persistent bone or muscle pain, muscle weakness, repeated fractures, or fatigue you think relates to vitamin D. A blood test establishes whether you are actually deficient and how much you need — and several conditions that mimic deficiency are treated quite differently.
Related supplement guides
Frequently asked questions
What is Calciferol used for? Treating and preventing vitamin D deficiency, supporting bone health, and managing osteoporosis, rickets and osteomalacia. Calciferol is vitamin D.
What are Calciferol tablets used for? The same purposes. In South Africa they are often 50,000 IU high-strength tablets taken weekly or monthly rather than daily — check your instructions.
Is calciferol the same as vitamin D? Yes. Ergocalciferol is vitamin D2 and cholecalciferol is vitamin D3.
What is the difference between D2 and D3? Both work. D3 is generally considered more effective at raising and maintaining vitamin D levels.
Can I take 50,000 IU every day? No, unless a doctor has specifically instructed it. High-strength products are normally weekly or monthly, and daily use can cause toxicity.
Do I need calcium as well? Often yes, particularly for bone health — vitamin D helps you absorb calcium, but cannot replace it. Check whether your product already includes it.
Can you take too much vitamin D? Yes. It is stored in the body, and excess causes raised blood calcium, with nausea, thirst, confusion and possible kidney damage.
Should I take it with food? Yes. Vitamin D is fat-soluble and absorbs better with a meal containing some fat.