The main cause of Vitamin B overdose is a high supplemental intake of the B vitamins. Over dosage does not usually result from dietary or food intake rich in Vitamin B complex. Instead, the oral supplementation can yield such. Physicians prescribe the right amount of B vitamins to be taken according to the case of the patient. Normal individuals do not usually need supplements because B vitamins are readily available from food sources.
Kidney problems
The Vitamin B complex is excreted from the body through urine. Chronic renal failure may result in over dosage in people taking vitamin B supplements in large amounts because of the inability of the kidneys to adequately form urine and release toxins in the body.