Harmful effects of polyethylene glycol include severe allergic reactions, such as chest tightness, breathing difficulty, hives, and itching or rash, according to Drugs.com. Other serious side effects include facial, lip, tongue and mouth swelling; diarrhea or stomach pain; and rectal bleeding or pain. Individuals who experience any of these symptoms should seek medical attention immediately. More common and less serious side effects include nausea, gas and bloating. Polyethylene glycol is a laxative that softens stool by retaining water in it.
Women who are breastfeeding, pregnant or planning to become pregnant should talk to their doctors before taking polyethylene glycol, explains Drugs.com. Physicians do not know whether this medication makes its way into breast milk. Individuals who are taking herbal preparations or dietary supplements or who have any allergies should tell their physicians or pharmacists before taking the laxative. People with kidney problems, stomach pain, vomiting or bowel habits that change for more than two weeks should not take the medication.
Companies produce polyethylene glycol 3350, marketed as MiraLax and GlycoLax, in a powder form with a measuring cap for consumers to measure their doses accurately, notes Drugs.com. Consumers mix the powder in 4 to 8 ounces of juice, soda, tea, coffee or water. Patients may not experience results for up to four days, but they should not take the laxative more often than their doctors' instructions state.