Colace Glycerin Suppositories provide gentle fast acting relief of occasional constipation and are available for adults and children. The benefit of using Colace Glycerin Suppositories is that they often work in as little as 15-30 minutes. Colace Glycerin Suppositories work by dissolving inside the rectum lubricating, irritating and softening fecal matter. Lubricating and softening fecal matter helps to prevent hemorrhoids which is caused by straining during a difficult bowel movement. The benefits of suppositories are their ease of use and predictability, giving you control over when and where.