This procedure should never be done without first consulting your doctor for advice based on your personal medical history and the current state of your health.
An enema is claimed by some people to be more gentle than some laxatives and suppositories. The enema works only to clear the last two to three feet of your digestive tract.
One useful point is that you may be able to schedule your plans so that you can time your enema conveniently. Laxatives may start working anytime and not necessarily in line with your schedule.
Source of Information : Your Guide to Colon Cleansing by By Peter Mason