--itis true that overdosing on B6 can have deleterious effects, particularly neuropathy--

http://www.neuro.wustl.edu/neuromusc...yridoxineintox

--but this is only on major doses that are well above those available in most B-complex formulations on the market. Of course, people can abuse vitamins as they can any other substance, and some who may be taking multiple b-complexes with very high B6 values may be putting themsleves at risk.

Interestingly, these effects have only been reported with the pyridoxine form of B6. Certain companies now sell the enzymatically activated P-5-P form of B6, which seems to be more easily metabolized and safer, as it does not need to be converted from pyridoxine in the liver, and it may also bypass certain genetic enzymatic deficiencies (though these would typically result in not enough B6 absorption rather than too much).