It is recommended that individuals using more than 2,000 iu vitamin D per day have their blood levels monitored. Large doses of vitamin D can cause hypercalcemia, signs include headache, weakness, nausea, vomiting, and constipation.
Individuals with hyperparathyroidism or kidney disease are at particular risk.
Vitamin D3 10,000 iu and Vitamin D3 5,000 iu and are not to be taken by pregnant or lactating women.
If pregnant or lactating, consult your physician before taking Vitamin D3 400 iu or Vitamin D3 1,000 iu.