The prep is the laxative. It depends on your dr as to which kind of prep that they use. Some take the gallon of go-lytely (which is obviously a bad name for it), fleets phospo-soda (in the little bottle that you mix with sierra mist or juice) and others including rectal suppository. Then usually eat a clear liquid diet-depending again on your drs request. Some people can't handle the smaller amount as it is harsh, but the 1 gallon one cleans you out thoroughly, supposed to be easier but my mom strongly disagrees. It would also depend on if he is looking into a sigmoidoscopy or total colonoscopy. Best wishes to you and call the dr ahead of time to see what your prep will be.
I've had both types, and I preferred the Fleets Phospho-soda over Go-Lytely.
After the first couple of glasses of Go-lytely, I wanted to vomit, and I still had a ton left to drink. At least with fleets, the drinking is over faster.
the perscription says tablets in the morning, then half lytely i need to start drinking between 4-5 hours.