Systematic review compares over-the-counter treatments for chronic constipation

Polyethylene glycol (PEG) and senna appear to be the best options for over-the-counter (OTC) treatment of chronic constipation, according to a recent study.

Researchers performed a systematic review of randomized controlled trials lasting at least four weeks that were published between 2004 and 2020 and evaluated OTC constipation treatments. They scored the studies using U.S. Preventive Services Task Force criteria, including randomization, blinding, and withdrawals, and adjudicated the strengths of evidence within each therapeutic category. Resulting recommendations were graded as A, B, C, D, and I according to the level of evidence (good, fair, or poor). The results were published in the June American Journal of Gastroenterology.

Forty-one studies were included in the review. The researchers found good evidence (grade A) for PEG (an osmotic laxative) and senna (a stimulant). In addition, they found moderate evidence (grade B) for psyllium, SupraFiber (a brand-name supplement that contains fruit), magnesium salts, bisacodyl and sodium picosulfate, fruit-based laxatives (kiwi, mango, prunes, and ficus), and yogurt with galacto-oligosaccharide/prunes/linseed oil. The evidence was insufficient for polydextrose, inulin, and fructo-oligosaccharide. Diarrhea, nausea, bloating, and abdominal pain were commonly reported, but there were no serious adverse events.

The authors noted that they included only English-language studies and excluded studies of fewer than four weeks' duration. They concluded that although more OTC products for constipation have become available and the quality of the evidence has increased, methodologic issues such as variability in study design and small sample sizes persist. “We found good evidence to recommend polyethylene glycol or senna as first-line laxatives and moderate evidence supporting fiber supplements, fruits, stimulant laxatives, and magnesium-based products,” the authors wrote. “For others, further validation with more rigorously designed studies is warranted.”