Magnesium citrate typically takes about 30 minutes to 6 hours to start working. It acts as a saline laxative by drawing water into the intestines, which softens stool and helps stimulate bowel movements. The exact time it takes can vary based on factors such as individual digestive system, dosage, hydration level, and whether it is taken on an empty stomach. The laxative effect generally lasts for around 4 hours, with normal bowel habits resuming within a day after use. Early signs of it working include abdominal cramping, urgency to use the bathroom, and loose stools.