 Metabolism of methanol produces some extremely toxic compounds, such as formaldehyde and formic acid, which may play a role in the severity of hangover.Ethanol slows the conversion of methanol into its toxic metabolites so that most of the methanol can be excreted harmlessly in the breath and urine without forming its toxic metabolites.This may explain the temporary postponement of symptoms reported in the common remedy of drinking more alcohol to relieve hangover symptoms.