Colace is one of the most widely used over-the-counter stool softeners, but the evidence that it actually works for constipation is surprisingly weak. Multiple clinical trials dating back decades have compared docusate sodium (the active ingredient in Colace) to placebo, and the results are consistent: it performs no better than a sugar pill for improving stool frequency, consistency, or comfort.
That doesn’t mean Colace is harmful. It’s quite safe. But if you’re dealing with real constipation, there are better options backed by stronger evidence.
What the Clinical Evidence Actually Shows
At least six controlled trials have tested docusate sodium against placebo, and the pattern is remarkably consistent. A 2013 study of 74 hospice patients found no difference in stool frequency, volume, or consistency between docusate and placebo. A larger study of 170 people with chronic constipation found that by the second week, a fiber supplement (psyllium) increased bowel movement frequency while docusate “essentially had no effect on stool water content or water weight.” An earlier trial of nursing home residents found no difference in weekly bowel movements, no reduction in the need for additional laxatives, and no improvement in patients’ own ratings of constipation or discomfort.
A review published in the Journal of Hospital Medicine examined this body of research and concluded that prescribing docusate for constipation in hospitalized adults is something clinicians do “for no reason.” The most recent joint guideline from the American Gastroenterological Association and the American College of Gastroenterology didn’t even include a recommendation for docusate, noting that properly designed trials are still needed to clarify whether stool softeners actually improve outcomes.
How Colace Is Supposed to Work
Colace belongs to a class called surfactant laxatives. The idea is that docusate sodium acts like a detergent in your intestines, helping water and fat mix into the stool to make it softer and easier to pass. In theory, this sounds reasonable. In practice, the effect appears too mild to make a noticeable clinical difference for most people.
When it does have any effect, it takes 12 to 72 hours to kick in. That slow onset is another reason it’s a poor choice if you need relief now. Stimulant laxatives and osmotic laxatives both tend to work faster and more reliably.
Why It’s Still So Popular
Colace has a reputation for being gentle and safe, which is true. It causes very few side effects, and that low risk profile is exactly why it became a default recommendation after surgery, during pregnancy, and in nursing homes. Doctors prescribed it almost reflexively for decades, and the habit stuck. Many people still reach for it because a healthcare provider once told them to, or because stool softeners feel like a milder, more “natural” step than a laxative.
The problem isn’t safety. It’s that gentleness and effectiveness aren’t the same thing.
What Works Better
If you’re looking for an over-the-counter option with solid evidence behind it, you have several choices that outperform Colace.
- Psyllium fiber (Metamucil): In a head-to-head trial against docusate, psyllium increased both stool water content and bowel movement frequency within two weeks, while docusate did not. Fiber supplements work by bulking up stool and drawing water into it. They’re most effective when you drink plenty of water alongside them.
- Polyethylene glycol (MiraLAX): This osmotic laxative pulls water into the colon and is one of the best-studied treatments for chronic constipation. It typically produces a bowel movement within one to three days and can be used daily for longer stretches.
- Stimulant laxatives (bisacodyl, senna): These cause the muscles in your intestinal wall to contract and push stool through. They work faster, often within 6 to 12 hours, but aren’t ideal for daily long-term use.
For occasional constipation, starting with increased fiber, water, and physical activity is a reasonable first step. If that isn’t enough, an osmotic laxative like polyethylene glycol is generally the next move.
Colace During Pregnancy and Breastfeeding
Colace has long been a go-to recommendation during pregnancy because there’s no evidence it harms the baby. According to the NHS, docusate is occasionally used in pregnancy, but other laxatives are usually tried first simply because more safety data exists for those alternatives. If you’re breastfeeding, only a tiny amount of docusate is likely to pass into breast milk, and it’s not expected to affect your baby.
That said, the same effectiveness problem applies. If constipation during pregnancy is significant enough to need treatment, dietary changes and a better-studied laxative may be more helpful than Colace alone.
Is There Any Reason to Use Colace?
The one scenario where Colace still shows up frequently is post-surgical recovery, particularly after procedures where straining could cause complications. Even here, the evidence is thin. A randomized trial of women recovering from pelvic floor surgery found no significant difference between the group taking docusate alone and the group taking docusate plus an osmotic laxative. Some surgeons continue to recommend it out of convention, or as part of a combination regimen where the real work is being done by a different laxative taken alongside it.
If your provider has recommended Colace as part of a post-surgical plan, it’s fine to take. It won’t cause problems. But if you’re buying it on your own for general constipation relief, you’re likely spending money on something that won’t do much more than a placebo. A fiber supplement or osmotic laxative is a more evidence-based starting point.