Miralax (Polyethylene Glycol), an osmotic laxative, is a non-addictive oral laxative that is indicated for the relief of constipation. It typically is considered a first line laxative in most situations as it is non-additive and non-habit forming. In fact, clinical trials lasting as long as 6 months have shown that doses of 17 grams per day in adults produced few, if any, side effects.

Unlike other over the counter (OTC) laxatives such as bisacodyl, Miralax is a laxative that does not produce what is known as tachyphylaxis (a diminishing response to successive doses of a drug, making it less effective). In addition to tachyphylaxis, when stimulant laxatives are taken for too long, patients may become dependent on them and find it difficult to produce a bowel movement without the aid of a laxative product. Miralax doesn't have this problem because it is considered to be a non-active drug is not significantly absorbed into the body when taken by mouth. Nearly 100% of the dose stays in the GI tract and binds water which in turn produces softer stools as water is retained within the stool.

Doses above 17 grams per day can sometimes cause bloating and diarrhea in patients, especially elderly ones. If this occurs, it is often recommended to reduce the dosage or switch to a product that is better tolerated.