Constipation: work in different ways to relieve constipation. Milk of magnesia (magnesium hydroxide), a saline laxative, works the fastest and can produce a bowel movement in 30 minutes to six hours. Stimulant laxatives, like Ducolax (bisacodyl), Ex-Lax (sennosides), and Senokot (senna glycoside), take 12 to 24 hours to work. Miralax (polyethylene glycol 3350), an osmotic laxative that draws water into the intestines, can take up to three days to produce a bowel movement. , Peppermint also helps digestive fluids, called bile, move easily through the digestive tract, allowing food to break down more quickly. This may help people with constipation-predominant (IBS-C) in which stomach pain is accompanied by constipation., It is often possible to treat the symptoms of stomach pain using home remedies. In this article, we look at 12 of the most popular natural remedies for treating an upset stomach..