Magnesium Citrate works best for me and I've tried it all. Risperdal constipated me so badly I thought the stool would needs to be surgically removed (sorry for the TMI, just want you to know I really do understand your pain). Magnesium Citrate is not only the most effective, but it also provides the most cramp free relief. It's a little bottle of fizzy soda....drink the bottle followed by a large glass of water and within 24 hours max, you will be sorted out for awhile at least. Be sure to stay next to the toilet.