Safety and side effects

Taken in typical doses, vitamin D is thought to be mainly safe.

But taking too much vitamin D in the form of supplements can be harmful and even deadly. Taking more than 4,000 IU a day of vitamin D might cause:

• Upset stomach and vomiting.
• Weight loss and not wanting to eat.
• Muscle weakness.
• Not being able to think clearly or quickly.
• Heart rhythm issues.
• Kidney stones and kidney damage.