The best approach for constipation depends on whether you’re dealing with an occasional bout or a persistent pattern, but for most people, an osmotic laxative called polyethylene glycol (sold as MiraLAX and generics) is the strongest evidence-backed option. Major gastroenterology guidelines give it their highest recommendation alongside several prescription medications. Before reaching for any product, though, dietary and lifestyle changes resolve many cases on their own and are worth trying first.
Constipation is generally defined as fewer than three bowel movements per week, or stools that are hard and lumpy more than a quarter of the time. If that sounds familiar, you’re in good company: it’s one of the most common digestive complaints.
Fiber: The Foundation
Adults need 22 to 34 grams of fiber per day, depending on age and sex. Most Americans get roughly half that. Closing the gap is the simplest first step, and it works for a large percentage of people with mild constipation. Good sources include beans, lentils, whole grains, berries, broccoli, and pears. The key is to increase your intake gradually over a week or two, because adding too much fiber at once can cause bloating and gas.
Fiber only works well when you’re drinking enough water. Without adequate fluid, extra fiber can actually make things worse by bulking up stool without softening it. There’s no single magic number for water intake since it depends on your size, activity level, and climate, but aiming for at least eight glasses a day is a reasonable starting point for most adults.
If you’d rather take a supplement than overhaul your diet, psyllium husk (the ingredient in Metamucil) is the most studied option. It’s a soluble fiber that forms a gel in the gut, softening stool and helping it move. Expect results within 12 hours to three days. Gastroenterology guidelines give fiber a conditional recommendation, meaning it helps many people but isn’t as consistently effective as stronger options.
Prunes Actually Work
Prunes aren’t just folk wisdom. In a randomized controlled trial published in the American Journal of Gastroenterology, dried plums increased the number of complete, spontaneous bowel movements per week just as effectively as psyllium. Both produced a statistically significant improvement over baseline. Prunes contain sorbitol, a natural sugar alcohol that draws water into the intestine, plus a modest amount of fiber. About five to six prunes a day (roughly 50 grams) is a typical amount used in studies. Prune juice works too, though it lacks some of the fiber content.
Over-the-Counter Laxatives Compared
When dietary changes aren’t enough, over-the-counter laxatives are the next step. They fall into a few categories, each with different strengths, timelines, and trade-offs.
Osmotic Laxatives
These pull water into the intestine, softening stool and stimulating movement. Polyethylene glycol (PEG) is the standout here. A joint guideline from the American Gastroenterological Association and the American College of Gastroenterology gives it a strong recommendation for chronic constipation, placing it in the same tier as prescription medications. It’s tasteless, mixes into any drink, and is well tolerated for long-term use. Most people see results within one to three days.
Lactulose is another osmotic option, available by prescription in some countries and over the counter in others. It works on the same principle but has been shown to be less effective than PEG in head-to-head trials. One well-designed study in patients found PEG had nearly double the success rate of lactulose (56% vs. 29%).
Stimulant Laxatives
Senna (Senokot) and bisacodyl (Dulcolax) work by triggering the muscles lining your intestine to contract. They act faster than osmotic laxatives, typically within 6 to 12 hours, which makes them useful for occasional, short-term relief. Guidelines recommend reserving stimulant laxatives for situations where osmotic options haven’t worked. Long-term daily use can lead to cramping, diarrhea, and, in some cases, the bowel becoming less responsive over time. That said, senna does receive a conditional recommendation for chronic constipation, meaning it’s not off-limits for ongoing use under guidance.
Bulk-Forming Laxatives
These are essentially fiber supplements (psyllium, methylcellulose). They’re the gentlest option but also the slowest, taking 12 hours to three days to work. They’re a good choice for mild, chronic constipation when you want something you can take daily without concern.
Magnesium Supplements
Magnesium oxide is a common, inexpensive option that works as a mild osmotic laxative. It draws water into the bowel and typically produces a result within a few hours to a day. Gastroenterology guidelines give it a conditional recommendation for chronic constipation. Magnesium citrate is a liquid formulation that acts more aggressively and is often used for short-term relief or bowel preparation before medical procedures. It’s not intended for regular daily use.
If you have kidney problems, talk to your provider before using magnesium products, since the kidneys are responsible for clearing excess magnesium from the body.
Exercise and Gut Motility
Physical activity speeds up the time it takes food to move through your colon, and the evidence backs this up. A study in the Journal of Neurogastroenterology and Motility found that combining a healthy diet with at least 500 MET-minutes of physical activity per week significantly reduced constipation risk. That threshold translates to roughly 150 minutes of brisk walking per week, or about 75 minutes of jogging. The effect was consistent whether constipation was measured by stool hardness or by frequency.
You don’t need to train for a marathon. A daily 20- to 30-minute walk, especially after meals, can meaningfully improve bowel regularity. The combination of movement and a high-fiber diet was more effective than either one alone.
A Practical Order of Operations
For occasional constipation, the most reasonable progression looks like this:
- Start with fiber and water. Increase fruits, vegetables, and whole grains while drinking more fluids. Add prunes or a psyllium supplement if whole foods aren’t moving the needle.
- Add daily movement. Even light exercise helps the gut contract more regularly.
- Try an osmotic laxative. Polyethylene glycol is the best-supported option for both occasional and ongoing use.
- Use stimulant laxatives sparingly. They’re effective for short-term relief but aren’t ideal as a daily solution.
If you’ve been following this progression for several weeks without improvement, prescription options exist. Medications that increase fluid secretion in the gut or that speed up intestinal contractions have strong evidence behind them and are specifically designed for people who don’t respond to over-the-counter treatments.
Signs Something Else Is Going On
Most constipation is functional, meaning there’s no underlying disease causing it. But certain symptoms suggest something beyond routine sluggish bowels. Blood in your stool, unintentional weight loss, or new-onset anemia alongside constipation are red flags that the American Gastroenterological Association identifies as reasons for further evaluation, typically a colonoscopy. A sudden, persistent change in bowel habits after age 45, especially if you haven’t had routine colon cancer screening, also warrants a closer look.