How much vitamin D should I take?
Last updated September 3, 2026.
600 IU (15 mcg) daily for adults to age 70 and 800 IU (20 mcg) after that, per the NIH, with a hard upper limit of 4,000 IU (100 mcg); the NHS advises 10 mcg (400 IU) daily for everyone over one year old, with extra emphasis on supplementing through autumn and winter. Many adults in northern latitudes run low, and only a blood test shows your actual level - worth having before taking big doses, because vitamin D overdose causes real harm (calcium buildup, kidney strain), unlike most vitamins. A sensible default for most adults is 400 to 1,000 IU daily, escalating only on test results. Pymander is a free AI doctor, 24/7 by text, and can help you interpret your level.
What to do
- Default: 400 to 1,000 IU daily: inside every major guideline.
- Never exceed 4,000 IU daily without supervision: excess D is genuinely toxic.
- Winter in a northern climate? Supplement: sunlight cannot cover it.
- Considering high doses? Test first: a level turns guessing into dosing.
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