<p>Vitamin C has little toxicity and only mega-doses of vitamin C may cause diarrhoea, abdominal bloating, iron over-absorption that is harmful in patients with thalassaemia, sideroblastic anemia, and haemochromatosis; hyperoxaluria, hyperuricosuria, and hemolysis in patients with glucose-6 phosphate dehydrogenase deficiency. A pregnant woman taking more than 5 gm/day may suffer fetal abortion.</p>