Vitamin D

What happens if you take too much vitamin D?

Updated 3 Nov 2026

Short answer

Too much vitamin D raises the calcium in the blood. This can cause nausea, vomiting, muscle weakness, pain, loss of appetite, thirst, frequent urination and kidney stones.[1] It almost always comes from supplements, not from the sun.[1] The adult upper limit is 4000 IU (100 µg) a day.[1][2]

What too much does

Too much vitamin D works through calcium, in this order:[1]

  1. Vitamin D makes the gut absorb more calcium.[1]
  2. Blood calcium rises above 11.1 mg/dL. The normal range is 8.4 to 10.2 mg/dL. This is called hypercalcemia.[1]
  3. More calcium also leaves in the urine (hypercalciuria), and the blood level of 25(OH)D is usually above 375 nmol/L (150 ng/mL).[1]
  4. High calcium can cause nausea, vomiting, muscle weakness, pain, loss of appetite, dehydration, thirst, frequent urination and kidney stones.[1]
  5. In extreme cases it causes kidney failure, calcium deposits in the heart and blood vessels, heart rhythm problems and death.[1]

Cases of poisoning came from supplements with too much vitamin D after a manufacturing error, from wrong use and from wrong prescriptions.[1] Experts do not think that sun on the skin causes it, because the skin turns extra previtamin D3 into inactive forms. Frequent use of tanning beds can raise the blood level above 375 nmol/L.[1]

How much is too much

The US tolerable upper intake level is 4000 IU (100 µg) a day from age 9, also in pregnancy and breastfeeding.[1] For younger children it is lower:[1]

  • under 6 months: 1000 IU (25 µg)[1]
  • 7 to 12 months: 1500 IU (38 µg)[1]
  • 1 to 3 years: 2500 IU (63 µg)[1]
  • 4 to 8 years: 3000 IU (75 µg)[1]

In 2023 EFSA, the EU food safety agency, set 100 µg a day for adults, pregnant and breastfeeding women and adolescents aged 11 to 17. For children aged 1 to 10 it set 50 µg.[2] EFSA based the limit on too much calcium in the urine, seen at 250 µg (10,000 IU) a day in two trials. It divided that dose by 2.5 for safety.[2]

The US experts noted that symptoms are unlikely below 10,000 IU a day. They also said that intakes below the upper limit might have harmful effects over time, and advised against blood levels above about 125 to 150 nmol/L.[1]

What trials found at higher doses

  • 3200 to 4000 IU a day for 6 months or more, 22 trials with 12,952 people: high blood calcium was 2.21 times as common, about 4 extra cases per 1000 people.[3] Falls were 25% and hospital stays 16% more common. Kidney stones and deaths did not differ.[3]
  • Any dose for 24 weeks or more, 48 studies with 19,833 people: high blood calcium was 54% and high urine calcium 64% more common, but kidney stones were not.[4]
  • 500,000 IU once a year in women aged 70 or older: 15% more falls and 26% more fractures.[5]
  • 2000 IU a day for a median of 5.3 years in VITAL: no more cases of high blood calcium than with a placebo.[6]

Calcium and vitamin D together

In a 7-year trial of 36,282 women after menopause, 1000 mg of calcium with 400 IU of vitamin D a day raised the risk of kidney stones by 17%. Shorter trials found more high blood and urine calcium, but not more kidney stones.[1]

Who should be careful

  • People who take a thiazide diuretic, mostly older adults and people with kidney problems or an overactive parathyroid gland: the combination can raise blood calcium.[1]
  • Anyone who takes more than the upper limit, or one very large dose once a year.[1][5]
  • Parents of babies and young children, whose upper limits are much lower.[1]

People in these groups should ask a doctor or pharmacist first. NIH ODS advises people who take medicines regularly to discuss their vitamin D intake with their health care provider.[1]

Sources (6)

  1. Vitamin D: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. ods.od.nih.gov
  2. 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
  3. Long-term supplementation with 3200 to 4000 IU of vitamin D daily and adverse events: a systematic review and meta-analysis of randomized controlled trials. Zittermann A, Trummer C, Theiler-Schwetz V, Pilz S Eur J Nutr, 2023. PMID 36853379
  4. Hypercalcemia, hypercalciuria, and kidney stones in long-term studies of vitamin D supplementation: a systematic review and meta-analysis. Malihi Z, Wu Z, Stewart AW, Lawes CM, Scragg R Am J Clin Nutr, 2016. PMID 27604776
  5. Annual high-dose oral vitamin D and falls and fractures in older women: a randomized controlled trial. Sanders KM, Stuart AL, Williamson EJ, Simpson JA, Kotowicz MA, Young D, et al. JAMA, 2010. PMID 20460620
  6. 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

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?Is vitamin D safe?Does vitamin D prevent fractures?

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