Citrucel with Smartfiber Caplets, 100 Count Fiber for irregularity that wont cause excess gas. (Based on laboratory testing. Individual results may vary.) Clinically proven** effective to relieve occasional constipation. Citrucel contains Methylcellulose Fiber, which is a non-toxic, non-allergenic, and non-irritant fiber. Convenient caplet form  no mixing, no mess. Contains Methylcellulose Fiber, a fiber derived from cellulose. Available in 100-count, 180-count, and 240-count caplets. Citrucel is recommended by physicians (among therapeutic fiber laxatives). **Snape W. The Effect of Methylcellulose on Symptoms of Constipation. Clinical Therapeutics .1989; Sep-Oct;11(5):572-9.