Revisiting the evidence for neuropathy caused by pyridoxine deficiency and excess.

Pyridoxine deficiency and excess have been implicated as a cause for peripheral neuropathy. As a result, unrelated neuropathies are often treated with pyridoxine based on questionable evidence. However, neurological practitioners frequently discourage patients from taking pyridoxine in excess of 50 mg/d given concerns around the development of a toxic sensory neuronopathy. There is no systematic review to support either of the 2 practices. To address this gap in knowledge, we reviewed the available literature on neuropathy attributed to pyridoxine deficiency and excess. Based on the current limited data, it can be concluded that very low doses of daily pyridoxine are required to prevent peripheral neuropathy. There is inadequate evidence to support routine pyridoxine supplementation in patients with disorders of peripheral nervous system. Supplementation with pyridoxine at doses greater than 50 mg/d for extended duration may be harmful and should be discouraged.