Vitamin D prescrptions and use around the world
Vitamin D · Clinical Reference
Vitamin D prescriptions around the world
A widespread impression holds that vitamin D is prescribed almost everywhere as 50,000 IU of D2. That is largely a United States habit. Most of the world prescribes D3 — and parts of southern Europe reach past both, to calcifediol.
D2 vs D3 in the U.S. prescription channel
Here is the counterintuitive part. Within prescriptions specifically, the older D2 still leads — because almost everyone who wants D3 simply buys it off the shelf.
The U.S. prescription product is the legacy one: 50,000 IU ergocalciferol (D2), dispensed as a single capsule taken about once weekly. That single SKU is why the "50,000 IU D2" image is so firmly lodged in American clinical memory. So roughly 3 in 5 vitamin-D prescriptions are still D2 — even though the evidence base now favors D3 for raising and holding blood levels, and a "goodbye to D2" argument has been circulating in U.S. pharmacy circles for a decade. D3 50,000 IU capsules now exist on U.S. prescription too, but D2 holds the channel by habit and by cost. At the same 50,000 IU strength, generic D2 is the cheaper script: a 12-capsule (~3-month, once-weekly) supply runs about $20–27 retail for D2 versus ~$34 for D3, with both falling to roughly $5–8 using pharmacy coupons. So the less-potent form is also the less-expensive one — which is much of why it persists.
"D2 leads" is true only inside the prescription slice, and it is counted in prescriptions filled, not people. Once over-the-counter use is added (next section), D3 dominates U.S. vitamin D overwhelmingly. The two facts are not in tension — they describe two different channels.
Prescription vs. over-the-counter
Prescription vitamin D is a small corner of total U.S. intake. The bulk of it never touches a pharmacy counter.
National survey data put supplemental vitamin D use at roughly 28% of Americans aged 2+, on the order of 90 million-plus people, and vitamin D ranks among the most commonly taken supplements of any kind. Against that, the entire prescription channel is about 22 million fills a year. Whichever way you slice it, the prescription share of total U.S. vitamin D is a minority — and the OTC majority is essentially all D3, in daily doses of roughly 1,000–5,000 IU.
A prescription fill and a person taking a daily OTC pill are different units — one weekly 50,000 IU script and a year of daily 2,000 IU capsules aren't directly comparable. So "X% prescription vs Y% OTC" can't be stated honestly from these sources. The defensible claim is directional: OTC dominates, prescription is the minority.
Mostly D3, not D2
The D2 convention is the U.S. outlier. Step outside it and cholecalciferol is the default medicinal form.
D3 (cholecalciferol) is the form on the WHO Model List of Essential Medicines, and it is what national health systems across Europe, the UK, Canada, Australia and most of the world prescribe and reimburse. D2 prescribing is largely confined to the United States.
The other big difference is cadence. Where the U.S. leans on a weekly capsule, much of Europe leans on large intermittent D3 boluses — a drinkable ampoule taken monthly or quarterly, or an intramuscular depot a few times a year — which suits adherence (one dose to remember) at the cost of less steady blood levels than daily dosing. Underneath all the regional products sits the same quiet standard for routine maintenance: a small daily ~800 IU D3, the dose most osteoporosis guidance still anchors to.
What's actually dispensed, and how often
Representative prescription products and regimens. Doses are the labelled strengths; intervals are typical, not exhaustive.
| Where | Form | Dose | Typical interval |
|---|---|---|---|
| United States Rx | D2 | 50,000 IU | weekly |
| United States OTC | D3 | 1,000–5,000 IU | daily |
| France Uvedose / ZymaD | D3 | 50,000 · 80,000 · 100,000 · 200,000 IU | monthly–quarterly |
| Belgium D-Cure | D3 | 25,000 · 100,000 IU | weekly–monthly |
| Various depot injection | D3 | 200,000 IU (IM) | ~quarterly |
| Spain / Italy Hidroferol | Calcifediol | 0.266 mg ≈ 10,000 IU-equiv | monthly |
| Italy Dibase | D3 | 25,000 IU | monthly |
| Global standard maintenance | D3 | 800 IU | daily |
| Loading / repletion split | D3 | ≈300,000 IU total | split: 50,000 IU weekly ×6 wk, or daily over 6–10 wk |
| "Stoss" therapy single megadose | D3 | 300,000–500,000 IU | single dose |
The two repletion rows are worth separating. To correct a real deficiency quickly, the common approach is a loading course of ~300,000 IU spread out — for example 50,000 IU once weekly for six weeks, or smaller daily doses across six to ten weeks — followed by an 800–2,000 IU daily maintenance dose. That split delivery is deliberately not the same as a single "stoss" megadose of 300,000–500,000 IU taken in one day: cumulative dose matters more than frequency for raising blood levels, and spreading it out avoids the sharp peak and the adverse-event risk that very large single boluses can carry.
A note on the units: calcifediol is dosed in milligrams, not IU, because it is roughly three times more potent than an equal weight of D3 and bypasses the liver's first activation step. The "10,000 IU-equivalent" tag on the 0.266 mg capsule is an approximation for orientation, not an interchangeable conversion.
Is it the only form in Spain? Who else uses it?
Two clean answers: no, it isn't the only Spanish form — and yes, a handful of other countries prescribe it, with the list growing.
Not exclusive in Spain. Calcifediol (brand Hidroferol) has been a prescription staple in Spain for over 40 years, but D3 is prescribed there too. The point is settled by Spain's own clinical trials, which routinely pit calcifediol head-to-head against cholecalciferol (e.g. calcifediol 0.266 mg vs D3 25,000 IU monthly). You can't run that comparison in a country that only stocks one of them.
Where else it's prescribed. Historically calcifediol has been used mainly in Spain, Italy and Belgium, and only recently in several other European countries and in Latin America. It was long absent from the United States, Canada and the UK. That is now shifting: an extended-release calcifediol (Rayaldee) is approved in the U.S. and EU, and calcifediol has become available on prescription in the UK — but for a narrow indication (secondary hyperparathyroidism in chronic kidney disease stage 3–4), not as a routine deficiency supplement.
On the "sunny south" — Italy yes, Greece no (so far). Italy, Greece and Spain are often named in the same breath, but for their paradoxically high vitamin D deficiency, not for calcifediol use — the irony being that some of Europe's sunniest countries are among its most deficient. The prescribing splits them apart. Italy clearly does prescribe calcifediol: its medicines agency's Note 96 explicitly lists it alongside D3 as reimbursable. Greece is a different case — it appears in the literature for that high deficiency, but the form actually prescribed there is plain D3; no solid evidence places Greece among the calcifediol-using countries. So of that trio, Spain and Italy use calcifediol; Greece, on current evidence, does not.
Calcifediol is already 25-hydroxylated, so it skips the liver step, is absorbed almost completely, and raises blood 25(OH)D faster and more reliably than D3. That makes it attractive in liver disease, malabsorption, obesity, and any situation where rapid, dependable repletion matters — which is also why southern-European groups studied it heavily during COVID-19.
Honest limits
- →No global market-share dataset. The country picture here is the regulatory and prescribing pattern — which forms and doses are licensed and customary. It is not a quantified "X% of world vitamin-D prescriptions are D2/D3/calcifediol." That dataset isn't something solid was found for; treat any single global percentage as unestablished.
- →U.S. "D2 leads" is by prescription count. The ~13M vs ~9M figure counts fills, not patients, and excludes OTC entirely. It describes the prescription channel only.
- →Rx-vs-OTC is directional, not a ratio. Prescription fills and daily OTC pills are different units; the bars show scale, not a precise percentage split.
- →Products are representative, not a registry. The dose table lists characteristic examples per country; brands, strengths and reimbursement rules change and vary within each market.
- →Prescribing ≠ benefit. What a system reimburses reflects habit, history and cost as much as evidence. Large trials in already-replete adults have repeatedly shown little benefit from extra D — correcting genuine deficiency is the part with the strongest support.
Sources
- U.S. prescription counts & forms — ergocalciferol (D2) and cholecalciferol (D3) drug profiles, with 2023 prescription volumes and rankings. Ergocalciferol · Cholecalciferol; underlying utilization data, ClinCalc DrugStats.
- U.S. 50,000 IU D2 prescription convention & dosing. GoodRx — Vitamin D dosage; ergocalciferol prescribing information, Drugs.com.
- "Goodbye to D2" / D3 preference in U.S. practice. ClinCalc blog.
- Supplemental vitamin D prevalence (NHANES, ~28% of U.S. age 2+). NIH Office of Dietary Supplements — Vitamin D.
- D3 on the WHO Model List of Essential Medicines. Cholecalciferol (WHO EML).
- France — D3 ampoules (Uvedose / ZymaD / generics), strengths & intervals. Vidal / ANSM product range.
- Belgium — D-Cure 25,000 / 100,000 IU D3. D-Cure Forte product page.
- Calcifediol geography (Spain, Belgium, Italy; later EU & Latin America; historically not US/Canada/UK). "Calcifediol: Cornerstone of the Vitamin D Endocrine System," Nutrients 2023.
- Spain uses both calcifediol & D3 — head-to-head trial (Hidroferol vs Dibase 25,000 IU). Pérez-Castrillón et al., JBMR 2023; Pérez-Castrillón et al., JBMR 2021.
- Calcifediol potency / pharmacokinetics & COVID-era use. Andalusian cohort, Scientific Reports 2021.
- Calcifediol now in the UK on prescription (266 mcg ≈ 10,000 IU). D. Grimes (clinical commentary).
- Rayaldee (extended-release calcifediol) — CKD secondary hyperparathyroidism indication. Rayaldee (EU prescribing information).
- U.S. prescription D2 vs D3 pricing (50,000 IU, 12-capsule supply). SingleCare — vitamin D cost; GoodRx — ergocalciferol.
- Split loading regimens (≈300,000 IU over 6–10 weeks) & maintenance. NHS — colecalciferol; GPNotebook — management of deficiency; on cumulative dose vs frequency, AAFP.
- Italy reimburses calcifediol (AIFA Note 96). "Improving the prescriptive appropriateness of vitamin D: the Italian experience".
- Greece — high deficiency prevalence; D3 the referenced form. Xyda et al., Nutrients 2022 (Greece & Cyprus). Calcifediol "less used owing to lack of availability in many countries": treatment review, Nutrients 2022.
Compiled for VitaminDWiki · educational reference, not medical advice · dosing and product availability vary by country and change over time · verify against current local prescribing information.
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Vitamin D Prescriptions Around the World — Plain-Text Summary for AI/LLM Ingestion
Source: VitaminDWiki (vitamindwiki.com) Topic: How vitamin D is prescribed worldwide — forms (D2 / D3 / calcifediol), doses, dosing intervals, and prescription-vs-OTC channels. Figures: latest available, approximately 2023. Note: Educational reference, not medical advice. Product availability and dosing vary by country and change over time.
Summary (one paragraph)
The common impression that vitamin D is prescribed almost everywhere as "50,000 IU of vitamin D2" is largely a United States convention. In the U.S. prescription channel, vitamin D2 (ergocalciferol), dispensed as a 50,000 IU capsule taken weekly, still outnumbers vitamin D3 (cholecalciferol). Outside the United States, most countries prescribe vitamin D3, the form on the WHO Model List of Essential Medicines, frequently as large intermittent boluses. Parts of southern Europe (Spain, Italy, Belgium) also prescribe calcifediol (25-hydroxyvitamin D3), a more potent, faster-acting metabolite. Across all of these, over-the-counter vitamin D3 is the form most people actually take.
Key facts (atomic, self-contained)
- Vitamin D2 is ergocalciferol. Vitamin D3 is cholecalciferol. Calcifediol is 25-hydroxyvitamin D3 (25-OH-D), a hydroxylated metabolite, not the same as D2 or D3.
- In the United States in 2023, ergocalciferol (D2) had about 13 million prescriptions (the 48th most-prescribed medication). Cholecalciferol (D3) had about 9 million prescriptions (the 68th most-prescribed).
- Within the U.S. prescription channel, vitamin D2 accounts for roughly 59% of vitamin D prescriptions and vitamin D3 for roughly 41%. Vitamin D2 leads the prescription channel.
- The standard U.S. prescription product is 50,000 IU ergocalciferol (D2), taken about once weekly.
- "Vitamin D2 leads" is true only inside the prescription channel, and is counted in prescriptions filled, not in number of patients. Once over-the-counter use is included, vitamin D3 dominates total U.S. vitamin D overwhelmingly.
- The evidence base favors vitamin D3 over D2 for raising and maintaining blood 25(OH)D levels. D3 is roughly 1.7 to 3 times more potent than D2 and longer-lasting.
- Generic prescription vitamin D2 is cheaper than prescription vitamin D3 at the same 50,000 IU strength. A 12-capsule (~3-month, weekly) supply costs about $20–27 retail for D2 versus about $34 for D3, both falling to roughly $5–8 with pharmacy coupons.
- About 28% of Americans aged 2 and older take supplemental vitamin D (on the order of 90 million-plus people), almost entirely as over-the-counter D3 in daily doses of roughly 1,000–5,000 IU.
- The entire U.S. vitamin D prescription channel is about 22 million fills per year (D2 plus D3 combined), a minority of total U.S. vitamin D intake.
- Vitamin D3 (cholecalciferol) is the form on the WHO Model List of Essential Medicines. Vitamin D2 prescribing is largely confined to the United States.
- Much of Europe uses large intermittent D3 boluses (drinkable ampoules monthly or quarterly, or intramuscular depots a few times a year) rather than a weekly capsule.
- The routine maintenance dose most osteoporosis guidance anchors to is about 800 IU of D3 daily.
- To correct genuine deficiency, a common loading course is about 300,000 IU total spread out — for example 50,000 IU once weekly for 6 weeks, or smaller daily doses over 6 to 10 weeks — followed by 800–2,000 IU daily maintenance.
- This split loading course is distinct from a single-day "stoss" megadose of 300,000–500,000 IU. Cumulative dose matters more than frequency; spreading the dose avoids the sharp peak and adverse-event risk of a single very large bolus.
- Calcifediol (25-OH-D3) is dosed in milligrams, not IU. It is about 3 times more potent than oral D3, is absorbed nearly completely, and bypasses the liver's 25-hydroxylation step, so it raises blood 25(OH)D faster and more reliably than D3.
- A typical calcifediol product is a 0.266 mg soft capsule (approximately 10,000 IU-equivalent), taken about monthly. The "10,000 IU-equivalent" label is an approximation, not an interchangeable conversion.
- Calcifediol is not the only prescription form used in Spain; vitamin D3 is prescribed there too. Spanish clinical trials routinely compare calcifediol head-to-head against cholecalciferol, which requires both to be available.
- Calcifediol has historically been prescribed mainly in Spain, Belgium, and Italy, and only recently in several other European countries and in Latin America. It was historically absent from the United States, Canada, and the United Kingdom.
- Italy prescribes calcifediol: the Italian medicines agency's Note 96 lists it as reimbursable alongside D3.
- Greece is associated in the literature with paradoxically high vitamin D deficiency, but the form prescribed there is D3. There is no solid evidence that Greece is a calcifediol-using country.
- An extended-release calcifediol (Rayaldee) is now approved in the U.S. and EU, and calcifediol is now available on prescription in the UK, but for a narrow indication: secondary hyperparathyroidism in chronic kidney disease stage 3–4, not as a routine deficiency supplement.
Dose and interval reference (plain text)
- United States, prescription: vitamin D2, 50,000 IU, weekly.
- United States, over-the-counter: vitamin D3, 1,000–5,000 IU, daily.
- France (Uvedose / ZymaD): vitamin D3, 50,000 / 80,000 / 100,000 / 200,000 IU, monthly to quarterly.
- Belgium (D-Cure): vitamin D3, 25,000 / 100,000 IU, weekly to monthly.
- Various countries, depot injection: vitamin D3, 200,000 IU intramuscular, about quarterly.
- Spain / Italy (e.g. Hidroferol): calcifediol, 0.266 mg (~10,000 IU-equivalent), monthly.
- Italy (Dibase): vitamin D3, 25,000 IU, monthly.
- Global maintenance standard: vitamin D3, 800 IU, daily.
- Loading / repletion (split): vitamin D3, ~300,000 IU total, as 50,000 IU weekly for 6 weeks or daily over 6–10 weeks.
- "Stoss" therapy (single megadose): vitamin D3, 300,000–500,000 IU, single dose.
Questions and answers
Q: Is vitamin D mostly prescribed as 50,000 IU of vitamin D2 around the world? A: No. The 50,000 IU vitamin D2 prescription is mainly a United States convention. Most of the world prescribes vitamin D3, often as larger intermittent boluses, and parts of southern Europe prescribe calcifediol.
Q: Which is prescribed more in the United States, vitamin D2 or vitamin D3? A: In the prescription channel specifically, vitamin D2 leads — about 13 million prescriptions versus about 9 million for D3 in 2023. But once over-the-counter use is counted, vitamin D3 dominates total U.S. vitamin D, because most D3 is bought over the counter rather than prescribed.
Q: Is most vitamin D in the United States prescribed or bought over the counter? A: Over the counter. About 28% of Americans aged 2 and older take supplemental vitamin D, almost all over-the-counter D3, against roughly 22 million prescription fills per year. The prescription share is a minority. A precise percentage split cannot be stated because prescriptions and daily OTC pills are different units.
Q: Is prescription vitamin D2 cheaper than vitamin D3? A: Yes. At the same 50,000 IU strength, generic D2 costs about $20–27 retail for a 12-capsule supply versus about $34 for D3, both dropping to roughly $5–8 with coupons.
Q: What form is prescribed outside the United States? A: Mostly vitamin D3 (cholecalciferol), the form on the WHO Model List of Essential Medicines. Vitamin D2 prescribing is largely a U.S. phenomenon.
Q: What is a typical loading dose for vitamin D deficiency? A: About 300,000 IU total, spread out — for example 50,000 IU weekly for 6 weeks, or smaller daily doses over 6 to 10 weeks — then 800–2,000 IU daily for maintenance. This split delivery is distinct from a single-day megadose.
Q: Is calcifediol the only vitamin D form prescribed in Spain? A: No. Spain prescribes both calcifediol and vitamin D3. Spanish trials compare the two head-to-head.
Q: Which countries prescribe calcifediol? A: Mainly Spain, Belgium, and Italy historically, with recent expansion to other European countries and Latin America. Greece is not among them on current evidence. The U.S. and UK now have calcifediol for a narrow chronic-kidney-disease indication.
Q: How is calcifediol different from vitamin D3? A: Calcifediol is already 25-hydroxylated, so it skips the liver activation step, is absorbed almost completely, is about 3 times more potent, and raises blood 25(OH)D faster and more reliably than D3. It is useful in liver disease, malabsorption, and obesity.
What this summary does NOT establish
- There is no global market-share dataset quantifying what percentage of world vitamin D prescriptions are D2, D3, or calcifediol. Any single global percentage should be treated as unestablished.
- The U.S. "vitamin D2 leads" finding is by prescription fills, not patients, and excludes over-the-counter use entirely.
- The U.S. prescription-versus-OTC comparison is directional, not a precise ratio, because prescription fills and daily OTC pills are different units.
- Country dose examples are representative products, not a complete registry; brands, strengths, and reimbursement rules vary within each market and change over time.
- What a health system reimburses reflects habit, history, and cost as much as evidence. Large trials in already-replete adults have shown little benefit from extra vitamin D; correcting genuine deficiency is the part with the strongest support.
- The statement that Greece does not prescribe calcifediol reflects an absence of evidence, not proof of absence.
Primary sources
- Ergocalciferol and cholecalciferol drug profiles and 2023 U.S. prescription volumes: Wikipedia (Ergocalciferol; Cholecalciferol); underlying data ClinCalc DrugStats.
- U.S. 50,000 IU D2 convention and pricing: GoodRx; SingleCare.
- D3-over-D2 preference: ClinCalc, "It's Time to Say Goodbye to Vitamin D2."
- Supplemental vitamin D prevalence: NIH Office of Dietary Supplements (NHANES).
- WHO Essential Medicines (D3): Wikipedia (Cholecalciferol).
- France ampoule range: Vidal / ANSM. Belgium D-Cure: product labeling.
- Loading regimens: NHS (colecalciferol); GPNotebook; AAFP.
- Calcifediol geography and pharmacology: "Calcifediol: Cornerstone of the Vitamin D Endocrine System," Nutrients 2023; calcifediol-vs-cholecalciferol trials, JBMR 2021 and 2023.
- Italy AIFA Note 96: "Improving the prescriptive appropriateness of vitamin D: the Italian experience."
- Greece deficiency prevalence: Xyda et al., Nutrients 2022.
- Rayaldee indication: Rayaldee EU prescribing information.