What are some of the more common side effects from vitamin D2?

Common side effects of excessive vitamin D2 in the body include vomiting, constipation, nausea, appetite loss, constant thirst, increased urination, changes in moods and unusual exhaustion, states WebMD. Also known as ergocalciferol, it is unsafe at high doses in excess of 4,000 units per day.

At normal doses, vitamin D2 usually does not have side effects, and large doses of vitamin D may be prescribed in the case of a deficiency, according to WebMD. However, some studies on maternal health suggest that high consumption of ergocalciferol during pregnancy is unsafe, as it may harm the fetus. Too much vitamin D can cause high levels of calcium, which can be harmful.