Vitamin D has very few side effects when used as directed. If you take very large doses of vitamin D, you could develop vitamin D toxicity. While this is uncommon, symptoms include nausea, vomiting, poor appetite, constipation, weakness, weight loss and kidney damage.itamin D has very few side effects when used as directed. If you take very large doses of vitamin D, you could develop vitamin D toxicity. While this is uncommon, symptoms include nausea, vomiting, poor appetite, constipation, weakness, weight loss and kidney damage.