After taking magnesium sulfate before a colonoscopy it is usual to empty the bowels between 4 and 6 hours, but it varies from person to person because each person is different and has a different response time to the sensitivity of the drug. Magnesium sulfate is a medication that promotes the bowel reflex or smooth bowel movements and is primarily used to induce diarrhea. After using magnesium sulfate, patients will experience mild abdominal pain, bloating and hyperactive bowel sounds in about half an hour, causing diarrhea symptoms, thus effectively acting as a diarrhea inducer. How long it takes to get clean after using magnesium sulfate varies from person to person – everyone is different and has different sensitivities to the medication – but it usually takes between four and six hours. Magnesium sulfate should be taken strictly in accordance with the recommended dosage, if a large amount of magnesium sulfate solution with too high a concentration is ingested, the magnesium salt absorbs a large amount of water from the intestinal wall tissues, leading to dehydration. However, it is forbidden to use it in patients with intestinal bleeding, patients with acute abdomen, pregnant women and menstruating women, and the method of magnesium sulfate purging needs to be chosen by the doctor according to the patient’s condition.