Vitamins & supplements · Fat-soluble vitamin
Vitamin D (Cholecalciferol, D3)
Vitamin D is essential for calcium absorption and bone health. Widely used to prevent and treat vitamin D deficiency.
OTCKidney warningLiver warningPaediatric useSenior precautionOverview & typical uses
Vitamin D is essential for calcium absorption and bone health. Widely used to prevent and treat vitamin D deficiency.
Primary uses
- Prevention and treatment of vitamin D deficiency
- Supporting bone and muscle health
How it works
Regulates calcium and phosphate absorption from the gut and their use in bones, muscles, and immune cells.
Available forms & strengths
- Tablet — 400 IU, 1000 IU, 2000 IU (Oral)
- Oral drops (Oral) · Paediatric
- High-dose sachet (weekly / monthly) — 60,000 IU (Oral) · Prescribed for deficiency
General precautions & contraindications
Do not use if
- High blood calcium (hypercalcaemia)
- Sarcoidosis (without clinical supervision)
Pregnancy
Generally considered safe. Recommended at usual daily amounts during pregnancy; very high supplemental amounts require clinical guidance.
Breastfeeding
Generally considered safe. Recommended for breastfeeding parents at usual amounts.
Kidney considerations
- Discuss with a clinician if you have kidney disease — activated forms may be preferred.
Liver considerations
- Severe liver disease affects activation — discuss with a clinician.
Paediatric use
Recommended for infants at 400 IU daily in many guidelines.
Older adults
Widely recommended year-round.
Common side effects
- Usually well tolerated
- Mild digestive upset at high amounts
Serious warnings — seek help if these appear
- Vitamin D toxicity with prolonged very high amounts (raised calcium, kidney problems)
- Serious allergic reaction (very rare)
Drug interactions
May raise blood calcium levels — monitor if used together.
Higher risk of digoxin toxicity if calcium levels rise.
Food & alcohol precautions
Best absorbed with a meal containing some fat.
Storage, missed dose & overdose
Storage
Store below 25 °C, out of reach of children.
If a dose is missed
For daily doses, take when remembered. For weekly/monthly high doses, follow clinician instructions.
Overdose
Chronic overdose can cause raised blood calcium, kidney problems, and confusion. Do not exceed the amount advised by a clinician.
What to monitor
- Get blood levels checked when treating a deficiency, especially before or after high-dose regimens.
Frequently asked questions
Requirements vary by skin tone, latitude, and season. Many people benefit from a modest daily supplement.
Medical references
- WHO / FAO Vitamin D guidance — World Health Organization
- Institute of Medicine Dietary Reference Intakes — IOM (US)
Content last reviewed: 2025-01-01
Medical disclaimer
This information is for educational purposes only and should not replace professional medical advice. Please consult a licensed pharmacist or clinician for advice tailored to your personal circumstances.