Laxatives work in different ways, and the effectiveness of each laxative type varies from person to person. In general, bulk-forming laxatives, also referred to as fiber supplements, are the gentlest on your body and safest to use long term. Metamucil and Citrucel fall into this category.axatives work in different ways, and the effectiveness of each laxative type varies from person to person. In general, bulk-forming laxatives, also referred to as fiber supplements, are the gentlest on your body and safest to use long term. Metamucil and Citrucel fall into this category.