Formaldehyde is then quickly metabolized to formic acid contributing to the metabolic acidosis seen in methanol poisoning. As with ethylene glycol the major toxicity is not from the substance itself, but from the toxic metabolites. In the case of methanol the metabolite responsible for the detrimental effects is primarily formate. If hepatic THF levels are reduced, as in the case of most primates, the formate will accumulate producing metabolic acidosis . Clinical Toxicology Methanol is a toxic alcohol whose major symptoms of toxicity may be delayed, since toxicity is mediated by its metabolite-formic acid.
Toxicity can be variable with methanol.
The variation in latency time to the development of symptoms is due to the slow metabolism of methanol to formate. This latency phase can be further delayed by the co-ingestion of ethanol. Methanol initially causes confusion and ataxia for several hours, similar to other alcohols. After the ingestion a latency phase develops, during which methanol is being metabolized into formate. In this period the patient may present with malaise, headache, vomiting and abdominal pain.