For most people, Milk of Magnesia should work overnight if taken at bedtime. However, if you have chronic constipation, particularly colonic inertia or slow transit constipation, it can take longer for laxatives to work. Every person responds differently. There are also other variables. Any saline laxative works better if taken on a completely empty stomach and followed with adequate amounts of water. If you take it on a full stomach and without a fairly large amount of water, it may be less effective.I have colonic inertia and I have to say that I too experience delayed results from laxatives. Some stimulant laxatives that are supposed to work in 8 hours wind up taking 24 to 36 hours. For my first colonoscopy, I did the prep where you take 2 doses of phospho soda about four hours apart beginning the afternoon before. Supposedly you are cleaned out before bedtime. I did not even have my first bowel movement until after arriving at the hospital the next morning. Not good.How much MOM are you taking? You may need a larger dose. Also, are you taking it on an empty stomach and following it with a decent amount of water?Ther bloating and the gas you are experiencing might indicate that it is not moving through you fast enough.