NutriStack
What is happening. Vitamin B6 (pyridoxine) is the cofactor for aromatic L-amino acid decarboxylase, the enzyme that converts 5-HTP to serotonin and L-DOPA to dopamine. While vitamin B6 alone does not cause serotonin syndrome, high-dose supplementation may theoretically enhance conversion of serotonin precursors and is most relevant when other serotonergic agents are present. Separately, prolonged high-dose pyridoxine carries its own risk of sensory peripheral neuropathy, which can overlap with linezolid's known dose- and duration-dependent peripheral neuropathy.
Mechanism. Pyridoxal-5-phosphate is the cofactor for decarboxylation of serotonin and catecholamine precursors, so it can augment monoamine synthesis. Independently, chronic high-dose pyridoxine causes a dose-dependent sensory neuropathy that overlaps with linezolid-associated peripheral neuropathy seen with extended courses.
Recommendation. Routine dietary or low-dose B6 is not a concern. Avoid high-dose pyridoxine supplements during prolonged linezolid therapy, both to avoid compounding peripheral neuropathy risk and because B6 facilitates serotonin synthesis if precursors are present. Report new numbness, tingling, or burning in the hands or feet to a clinician.