It is the basis of a number of laxatives (e.g., macrogol-containing products such as Movicol and polyethylene glycol 3350, or SoftLax, MiraLAX or GlycoLax). Whole bowel irrigation (polyethylene glycol with added electrolytes) is used for bowel preparation before surgery or colonoscopy. It is sold under the brand names GoLYTELY, GaviLyte-C, NuLytely, GlycoLax, Fortrans, TriLyte, Colyte, Halflytely, Softlax, Lax-a-Day, ClearLax and MoviPrep. In the United States, MiraLAX and Dulcolax Balance are sold without prescription for short term relief of chronic constipation, although there is now growing consensus in the medical community that these medications can be taken indefinitely to treat chronic constipation.^{[citation needed]} A 2007 comparison showed that patients suffering from constipation had a better response to these two medications than to tegaserod.^[7] These medications work by softening the fecal mass and making the gut very slippery. Although very effective, fecal incontinence is a common side effect of this medication.