Hughes was sent to the stands by referee Anthony Taylor after reacting furiously to the decision to book Marko Arnautovic for simulation during the first half of his side's 4-0 Premier League defeat to Tottenham.
The 52-year-old had earlier been angry that a foul on Jonathan Walters went unpunished, and confronted fourth official Jonathan Moss and assistant referee Peter Kirkup before being dismissed from the dugout.