Bowel stimulating enemas usually consist of water, which works primarily as a mechanical stimulant, or they may be made up of water with baking soda (sodium bicarbonate) or water with a mild hand soap dissolved in it. Buffered sodium phosphate solution draws additional water from the bloodstream into the colon to increase the effectiveness of the enema, but can be rather irritating to the colon, causing intense cramping or "griping." Mineral oil functions as a lubricant and stool softener, but often has the side effect of sporadic seepage from the patient's anus which can soil undergarments for up to 24 hours. Glycerol is a specific bowel mucosa irritant and when introduced in very dilute solution serves to induce peristalsis.
