No drug works for everyone, and Zelnorm is no exception. There are just going to be a certain percentage of people that it doesn't help.A couple of questions.Were you using stimulatory laxatives regularly (like more than once a week) before starting Zelnorm, and have you stopped them now? If you are dependant on Senna, Cascara, etc and stopped taking them it may take more than a couple of weeks for the colon to get working again.What is your diet like? Are you getting enough fiber and water in your diet to promote good bowel habits?Are you sure it is simple IBS-type constipation that you have? Have you been tested for motility issues or pelvic floor disfunction. If you have additional issues those may need to be addressed (and if you have true low motility....like you can go more than a week between bowel movements most of the time...then the extra fiber won't help)You might want to add some foods to the diet that tend to loosen up the stools. Fruits with sorbitol are often good for this. Apples, pears, peaches and other stone fruits, cherries. During the summer when fresh produce is abundant people in general tend to have looser stools. AND...if it isn't working at all, CALL THE DOCTOR. They need to know that, and they may have suggestions that are appropriate with your medical history, etc.K.