Vitamin D

Is vitamin D safe?

Updated 3 Nov 2026

Short answer

In VITAL, 2000 IU a day for a median of 5.3 years caused no more cases of high blood calcium or other side effects than a placebo.[1] The upper limit for adults is 4000 IU (100 µg) a day in the US and in the EU.[2][3]

Too much vitamin D over time raises blood calcium. This can cause nausea, vomiting, muscle weakness and kidney stones.[2] Ask a doctor or pharmacist first if you take a thiazide diuretic, a statin, a corticosteroid or orlistat.[2] More: What happens if you take too much vitamin D?

Sources (3)

  1. Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease. Manson JE, Cook NR, Lee IM, Christen W, Bassuk SS, Mora S, et al. N Engl J Med, 2019. PMID 30415629
  2. Vitamin D: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. ods.od.nih.gov
  3. Scientific opinion on the tolerable upper intake level for vitamin D, including the derivation of a conversion factor for calcidiol monohydrate. EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) European Food Safety Authority, 2023. efsa.onlinelibrary.wiley.com

More about vitamin d

What is vitamin D?How do you get vitamin D from sunlight and food?What is vitamin D used for?What vitamin D blood level is too low?Does vitamin D prevent fractures?Does vitamin D prevent colds and other respiratory infections?

For education; not medical advice. Talk to a doctor before you start, stop or change a supplement.