The predominant symptom is peripheral sensory neuropathy that is experienced as numbness, pins-and-needles and burning sensations (paresthesia) in a patient's limbs on both sides of their body. Patients may experience unsteadiness of gait, incoordination (ataxia), involuntary muscle movements (choreoathetosis) the sensation of an electric zap in their bodies (Lhermitte's sign), a heightened sensitivity to sense stimuli including photosensitivity (hyperesthesia), impaired skin sensation (hypoesthesia), numbness around the mouth, and gastrointestinal symptoms such as nausea and heartburn. The ability to sense vibrations and to sense one's position are diminished to a greater degree than pain or temperature. Skin lesions have also been reported.<unk>  may also contribute to burning mouth<unk> . Potential psychiatric symptoms range from anxiety, depression, agitation, and cognitive deficits to psychosis. Symptom severity appears to be dose-dependent (higher doses cause more severe symptoms) and the duration of supplementation with vitamin<unk>  before onset of systems appears to be inversely proportional to the amount taken daily (the smaller the daily dosage, the longer it will take for symptoms to develop). It is also possible that some individuals are more susceptible to the toxic effects of vitamin<unk>  than others.<unk>  has been reported in doses as low as 24 mg/day. Symptoms may also be dependent on the form of vitamin<unk>  taken in supplements. It has been proposed that vitamin<unk>  in supplements should be in pyridoxal or pyridoxal phosphate form rather than pyridoxine as these are thought to reduce the likelihood of toxicity. A tissue culture study, however, showed that all<unk>  vitamers that could be converted into active coenzymes (pyridoxal, pyridoxine and pyridoxamine) were neurotoxic at similar concentrations. It has been shown, in vivo, that supplementing with pyridoxal or pyridoxal phosphate increases pyridoxine concentrations in humans, meaning there are metabolic pathways from each vitamer of<unk>  to the all other forms. Consuming high amounts of vitamin<unk>  from food has not been reported to cause adverse effects. Early diagnosis and cessation of vitamin<unk>  supplementation can reduce the morbidity of the<unk> .
Megavitamin-B6 syndrome
Mercury poisoning
Zinc toxicity
Lead poisoning
Iron poisoning
Copper toxicity
Mercury Poisoning
Chromium toxicity