Alcohol inhibits inhibitions and then inhibits activations, equivocal actions discussed by Macduff and by the porter, who described how drink increased the desire but reduced the performance. The effects of chronic ingestion of alcohol are described viscerally by Sir Toby Belch in Twelfth Night, and were displayed cognitively through the confabulations of King George IV, who repeatedly informed the Duke of Wellington that he had been by his side at the Battle of Waterloo.

Intestinal bacteria may produce alcohol, and thus cause intoxication without the consumption of alcohol.