Taking a daily dose of over 50,000 international units of vitamin D can cause toxicity, according to Mayo Clinic. In comparison, the recommended dietary allowance of vitamin D for adults is only 600 international units. Vitamin D toxicity is rare, and most cases occur because of excess vitamin supplementation.
Nausea, vomiting, frequent urination, poor appetite and kidney problems are symptoms of vitamin D toxicity. These symptoms are caused by a calcium buildup in the bloodstream. Although doctors can prescribe additional medication, vitamin D toxicity is usually solved when patients stop taking excess vitamin supplements, reports Mayo Clinic. Excess sun exposure does not cause vitamin D toxicity.