Reported side effects of vitamin D include nausea, vomiting, headache, metallic taste, vascular or nephrocalcinosis, and pancreatitis. Reported contraindications to vitamin D include hypercalcemia in sarcoidosis; metastatic bone disease148; other granulomatous diseases, such as tuberculosis and Crohn disease (active phase) that have disordered vitamin D metabolism in activated macrophages149; and Williams syndrome150 (infantile hypercalcemia).
| SOURCE AND DOSE OF VITAMIN D* | SIDE EFFECT OR TOXICITY | COMMENTS |
|---|---|---|
| Maximum sun exposure | No known vitamin D toxicity, but too much exposure to UVB (burns) results in increased risk of skin cancer | 10 000 IU (oral equivalent easily achieved with full-body exposure and results in levels of 148–163 nmol/L); in lifeguards exposed to the sun, kidney stones are more common151 |
| About 10 to 15 min of sun exposure of hands and arms midday when sun is overhead needed to achieve daily requirement (about 400 IU) | No known side effects; too much exposure to UVB (burns) results in increased risk of skin cancer | Dark skin requires 4 times as much sun exposure to get the same dose |
| Use of 2000 IU in African Americans (after 1 y) | No known side effects | Failed to achieve a level of 80 nmol/L in 40% of patients53 |
| Use of 4000 IU for 6 mo | Improved mood the only side effect noted | Average level of 25-hydroxyvitamin D was 110 nmol/L,51 a level seen with adequate sun exposure; no increase in serum calcium noted |
| 4000 IU for 3 mo | No notable side effects52 | |
| Use of vitamin D2 (synthetic analogue) | Several metabolites with unknown side effects | Toxicity reported using higher levels152,153 |
UVB—ultraviolet B.
↵* Vitamin D3 unless specified.