Vitamin D drugs and supplements

In what forms are vitamin D drugs available?

The 2026 Türkiye expert consensus writes that oral vitamin D preparations are commercially available in the country as capsules, drops, and tablets, and that an intramuscular ampule preparation also exists. Capsule and tablet strengths range from low to very high amounts; drops range to very different concentrations per mL. ^[1] For this reason, the name of the form alone does not describe the amount or the use.

Are D2 and D3 the same?

Products contain “D2” (ergocalciferol) or “D3” (cholecalciferol). The NIH writes that both forms raise blood 25(OH)D levels and appear equivalent in curing rickets, but that most of the evidence indicates that D3 raises the level more and maintains it longer. ^[2] In the meta-analysis by Tripkovic and colleagues as well, D3 was found more effective; the difference appeared in trials with a single high dose and disappeared with daily use. ^[3] The Türkiye consensus also recommends cholecalciferol (D3) for supplementation and treatment. ^[1]

The NIH also reports that 25(OH)D (calcifediol) is three to five times more potent than D3 per equal microgram; the Türkiye consensus says hydroxylated forms (such as calcifediol) may be considered in situations such as malabsorption. These are products determined by a physician. ^{[1] [2]}

What is the difference between a drug and a food supplement?

In Türkiye there are two different frameworks. The health claims page of TİTCK (Turkish Medicines and Medical Devices Agency) defines a drug (human medicinal product) as a substance “presented as having properties for treating or preventing disease in humans” or used to correct physiological functions or for medical diagnosis. ^[5] A food supplement, by the definition reported by the Ministry of Agriculture and Forestry, is a food in which nutrients such as vitamins and minerals are presented in forms such as capsules, tablets, and dropper bottles, with a defined daily intake dose, for the purpose of supplementing the normal diet. According to the Ministry’s explanation, selling these products by presenting them as preventing, treating, or curing diseases is contrary to the legislation. ^[4]

This difference is reflected on the label even among products that look like the same “vitamin D drops.” The Food Supplements Communiqué (2013/49) requires the following statements on the label: the amount of the daily serving recommended for consumption, “Tavsiye edilen günlük porsiyonu aşmayın” (do not exceed the recommended daily serving), “Takviye edici gıdalar normal beslenmenin yerine geçemez” (food supplements cannot replace normal nutrition), “Çocukların ulaşamayacağı yerde saklayın” (store out of reach of children), “İlaç değildir. Hastalıkların önlenmesi veya tedavi edilmesi amacıyla kullanılmaz” (not a drug; not used to prevent or treat diseases), and a warning to consult a doctor in pregnancy, breastfeeding, illness, or medication use; the product label cannot carry a disease prevention or treatment claim. ^[6] The communiqué may have been amended later; the current text is in the Official Gazette (Resmî Gazete). This page does not give a list of which product has which status and does not recommend brands.

Practical result: if the box says “takviye edici gıda” (food supplement) and “İlaç değildir,” the product has food status and is not used to treat disease. A vitamin D product presented as a drug falls under the drug definition; the instructions of the physician and pharmacist are what applies for its use. A pharmacist can provide information on a product’s status.

How is the label read?

1. Unit: µg or IU? 1 µg = 40 IU; 25 µg = 1,000 IU. ^[2] The communiqué also requires that the units set for vitamins and minerals be used. ^[6]
2. Serving: One drop, one mL, one capsule, one spray? To which serving does the amount on the label belong?
3. Form: D2 or D3? Are there added components such as K2, calcium, or magnesium? The warfarin warning for products containing K is covered on the vitamin D3 K2 page.
4. More than one product: If a multivitamin, calcium-D, and a separate D product are used at the same time, the total amount should be calculated; the upper limits are on the vitamin D excess page.
5. User group: In infants, pregnancy, breastfeeding, or the presence of medication or disease, product choice should be made with a physician.

There is a separate official program for children; details are on the vitamin D in infants page.

Why are high-dose loading and injection a physician decision?

The Türkiye expert consensus writes that a loading regimen is not routinely required in adult deficiency and may be considered in situations where rapid correction is desired, such as very low 25(OH)D, osteoporosis with very high fracture risk, secondary hyperparathyroidism, or hypocalcemia. Higher amounts may be needed in people with obesity or malabsorption, but these approaches are limited to specific clinical scenarios, expert supervision, and biochemical monitoring. ^[1] This page deliberately does not give the numbers and schedules of those regimens: what is correct is determination by the physician according to the person’s weight, kidney and liver status, medications, calcium level, and other diseases.

The situation is stricter in infants and children. The Ministry of Health guide writes that vitamin D at a treatment dose should not be given based only on the serum 25(OH)D value (without ALP and/or PTH elevation); that a single high dose (stoss) should not be used for prophylaxis and for non-skeletal effects of vitamin D; and that dispensing ampules to children from pharmacies without a prescription must be strictly prevented. ^[8]

Are monthly or intermittent very high doses equivalent to daily use?

No, they cannot be accepted as the same. In the randomized trial by Bischoff-Ferrari and colleagues, 200 people aged 70 and over who had previously fallen received, for one year, 24,000 IU D3 monthly, 60,000 IU D3 monthly, or 24,000 IU D3 monthly plus 300 µg calcifediol. The high monthly doses were more successful in raising 25(OH)D to at least 30 ng/mL, but provided no benefit for lower extremity function and were associated with an increase in fall risk compared with the 24,000 IU group. ^[7]

This finding should be read with these limits: the trial was conducted in an older group with a history of falls, the doses studied are a specific regimen, and the results are valid for this population. The Türkiye consensus also writes that daily and intermittent regimens at equivalent total amounts carry similar efficacy and safety; however, the same text states that daily cholecalciferol is the form that best mimics continuous endogenous production, that in some studies it was associated with higher 25(OH)D exposure compared with intermittent regimens, and that very high single doses such as seasonal or annual 300,000–600,000 IU are not recommended, particularly because of fall and fracture risk in older adults. ^[1] The Tripkovic meta-analysis also reports that the D2–D3 difference becomes apparent with single high doses and disappears with daily use. ^[3] In short, the assumption “same total amount, same result” cannot be made safely for all groups and all modes of use; for this reason, the decision on high-dose intermittent use is not one a person can make on their own.

When should a physician or pharmacist be asked?

• If the unit or serving on the label is not understood,
• If more than one product containing D is used at the same time,
• If there is a situation such as infancy, pregnancy, breastfeeding, kidney disease, hyperparathyroidism, or sarcoidosis, or a regularly used medication such as a thiazide diuretic or warfarin,
• When a high-dose ampule, drinkable solution, or injection is suggested: its purpose, the monitoring plan (25(OH)D, calcium), and the person’s own test result.

Timing of use is covered on the when to take vitamin D page, and dietary sources on the foods containing vitamin D page.

Main guide: What is vitamin D? This guide does not recommend a personal dose.