If you are uncomfortable taking Senna and Cascarda (as I am), I suggest taking magnesium nightly. Magensium is gentle, and draws water into the bowel. I have been using it for 5 years, and as my health improved, I have had to take less and less to get the desired affect (a sign that my body is not dependent on it).
I like Twinlabs Magnesium 400mg. Because it comes in a capsule, I think it works much better than a hard pill. I take it as the last thing before I go to bed at night. When I was sicker, I had to take up to 5 caps a night. Now, I take between 1 and 2 depending on what I ate.