I just did my 5th bowel prep (4 colonoscopies and 1 surgery). The last 3 have been miralax and gatorade. I had no problems with that at all until this last time. My advice is do NOT chose green gatorade with the flavor of "tropical blend". It was sickening from the start and an hour into the prep I vomited it. Called the gi doc on call and he suggested I drink it more slowly and perhaps try another flavor. So my husband ran out and brought back yellow lemon-lime flavor and I mixed a new batch. That went down and stayed down. The "returns" from the green stuff looked liked juiced spinach up until the end (sorry) Despite these problems the gi doc said my prep was excellent.
Forget Tropical Blend! Blech