"Gabby is back in the hospital tonight being treated for a seriously infected past mouth injury. She continues to have deep swelling and adverse reactions to medications," publicist Lesley Burbridge said in an email to The Associated Press.
Earlier Sunday, the 20-year-old Douglas posted on social media that she was out of the hospital.
Douglas had been scheduled to present an award alongside teammates Simone Biles, Laurie Hernandez, Madison Kocian and Aly Raisman at Madison Square Garden.
"The fifth member of our team, Gabby Douglas, is having medical issues and unfortunately couldn't make it tonight," Biles said at the awards show. "Feel better, Gabby!"
Without Douglas, the four other Olympians took turns introducing the nominees for the best female video category, an award that went to singer Beyonce.
Nicknaming themselves the Final Five, the quintet of gymnasts won a combined nine medals, breaking the record of eight won by the 1984 and 2008 USA women's gymnastics teams.
"The five women nominated for best female video worked hard to be on top of their games," Raisman said from the VMA stage. "They're role models for us as we hope to be to a younger generation of women."
Information from The Associated Press was used in this report.