Macrogol, also known as polyethylene glycol (PEG), is used as a medication to treat constipation in children and adults. It is also used to empty the bowels before a colonoscopy. It is taken by mouth. Benefits usually occur within three days. Generally it is only recommended for up to two weeks. It is also used as an excipient. Side effects may include increased bowel gas, abdominal pain, and nausea. Rare but serious side effects may include an abnormal heartbeat, seizures, and kidney problems. Use appears to be safe during pregnancy. It is classified as an osmotic laxative. It works by increasing the amount of water in the stool. Macrogol came into use as a bowel prep in 1980 and was approved for medical use in the United States in 1999. It is available as a generic medication and over the counter. In 2020, it was the 226th most commonly prescribed medication in the United States, with more than 2million prescriptions. Typically it is formulated together with electrolytes. Medical uses Constipation Macrogol 3350, often in combination with electrolytes, is used for short-term relief of constipation as well as for long-term use in constipation of various causes, including in multiple sclerosis and Parkinson's disease patients (an often-overlooked non-motor symptom) as well as constipation caused by pharmaceutical drugs such as opioids and anticholinergics. Whole bowel irrigation with macrogol is part of the bowel preparation before surgery or colonoscopy. Limited data also support its use for the treatment of fecal impaction. In those with chronic constipation it works better than lactulose. A 2007 comparison showed that people with constipation had a better response to macrogol than to tegaserod. Popular types include: macrogol 3350, macrogol 4000, and macrogol 6000. The number represents the average molecular mass. Combining different molecular masses provides some control over the consistency. Excipient Macrogol is used as an excipient in pharmaceutical products. Lower-molecular-weight variants are used as solvents in oral liquids and soft capsules, whereas solid variants are used as ointment bases, tablet binders, film coatings, and lubricants. For example, PEG-2000 is one of the excipients in the Moderna COVID-19 vaccine. PEGylation Macrogols are also attached to biopharmaceutical drugs to slow down their degradation in the human body and increase their duration of action, as well as to reduce immunogenicity. This process is called PEGylation. Contraindications Contraindications for macrogol taken orally as a laxative are intestinal perforation, bowel obstruction, ileus, inflammatory