Uncle Vernon was purple-faced, shouting, his fists still raised; Aunt Petunia had her arms around Dudley, who was retching again.
He retched again and Ron leapt backwards out of the way.
We’re just gonna let Madam Marsh off first, though —’ there was a retching sound from downstairs, followed by a horrible spattering noise ’— she’s not feeling ’er best.’
Oh, what a thing to happen in the middle of all this worry, I’m just thrilled, oh, Ronnie — Fred and George were both making loud retching noises behind her back but Mrs Weasley did not notice; arms tight around Ron’s neck, she was kissing him all over his face, which had turned a brighter scarlet than his badge.
What with the regular sounds of retching, cheering and the sound of Fred and George taking advance orders from the crowd, Harry was finding it exceptionally difficult to focus on the correct method for Strengthening Solution.
There are no more uses of "retch" in the book.
Show samples from other sources
The smell made me retch.
Then I grew sick, and retched to vomit, but could not, for I had nothing in my stomach to bring up.
Daniel Defoe -- The Further Adventures of Robinson Crusoe