Vitamin D toxicity resulting from overzealous correction of vitamin D deficiency, Clin Endocrinol (Oxf). 2015

"...CONCLUSION:
Our data demonstrate an emergence of vitamin D toxicity as an increasingly common cause of symptomatic hypercalcaemia. Irrational use of vitamin D in mega-doses resulted in vitamin D toxicity in all cases. Awareness among healthcare providers regarding the toxic potential of high doses of vitamin D and cautious use of vitamin D supplements is the key to prevent this condition..." https://www.ncbi.nlm.nih.gov/pubmed/26053339