"It was pretty tough but I'm good," she told Us Weekly Thursday. "I'm a trouper."
Hough, 24, said she has been sick four times since November.
"This is the last one, I think! Too many planes!"
Hough wore an Alberta Ferretti dress, Giuseppe Zanotti heels and Martin Katz jewelry at the Tuesday premiere, Us Weekly reported. She attended the event with "Safe Haven" onscreen love interest Josh Duhamel and real-life boyfriend Ryan Seacrest, 38.
Hough said she's received a lot of pressure to marry Seacrest, who she has dated for nearly three years.
"It's funny. I think so many people are so concerned if we're getting married of not, we're like, 'For real? What's happening?' So now we're just playing along, making people think something," she said.