[InSteady]

The oversimplified answer is that there are potential toxins in foraged mushrooms that your liver needs to sort out, which is going to be even more problematic if it is busy dealing with acetaldehyde from the ethanol breakdown.

Pure lay speculation, but based on the fact that humans have been deliberately ingesting lots of alcohol for millennia (and mammals have been doing intermittently for untold millions of years), the liver may preferentially break down ethanol and then acetaldehyde even when substances that are problematic/deadly in lower concentrations are present. Alcohol metabolism has been optimized for.

Interesting anecdote, methanol causes intoxication similar to alcohol and is harmful but not deadly in and of itself. However, methanol ingestion can cause blindness and death specifically because the liver breaks it down quickly into formic acid, which then circulates throughout the bloodstream. In cases of methanol poisoning, the antidote is to drink alcohol (ethanol) in sufficient quantities, since the liver preferentially breaks down the alcohol, allowing the methanol to be broken down much slower to the point that it is no longer deadly (half-life goes from 2-3 hours to 90+ hours when ethanol is present).

[kristianp]

Do you have to have an amount of alcohol every hour for 90+ hours in that case?

[rubatuga]

Conversion half life >> excretion half life