For most adults with occasional or chronic constipation, polyethylene glycol 3350 (sold as MiraLAX and store-brand equivalents) is the single best-supported option. It’s the only over-the-counter laxative that received a strong recommendation for ongoing use in the joint guidelines from the American College of Gastroenterology and the American Gastroenterological Association. But the “best” choice depends on how quickly you need relief and whether your constipation is a one-time problem or a recurring pattern.
The Strongest Evidence: Osmotic Laxatives
Osmotic laxatives work by pulling water into your colon, which softens stool and makes it easier to pass. Polyethylene glycol 3350 is the gold standard in this category. The standard dose is 17 grams (about one capful) mixed into any beverage, once a day. It’s tasteless, dissolves easily, and is well tolerated over weeks or months of daily use. The tradeoff is patience: it can take one to three days to produce a bowel movement, so it’s not the right pick if you need fast relief.
Magnesium-based options are another osmotic choice. Magnesium citrate (the liquid sold in bottles at most pharmacies) and magnesium hydroxide (Milk of Magnesia) both draw water into the gut and tend to work faster, often within a few hours. User satisfaction ratings for both hover around 8 out of 10, with roughly 80% of people reporting a positive effect. The most common side effects are cramping, bloating, and diarrhea. Magnesium citrate is generally the stronger of the two and is better suited for occasional use rather than daily reliance, since large doses of magnesium can cause electrolyte imbalances over time.
When You Need Relief Tonight: Stimulant Laxatives
If you haven’t gone in days and want results by morning, stimulant laxatives are the fastest-acting oral option. These work by triggering the nerves in your colon wall, forcing the muscles to contract and push stool forward. Bisacodyl (Dulcolax tablets) and senna (Senokot) are the two most common choices, and both typically produce a bowel movement within 6 to 12 hours when taken at bedtime.
Clinical guidelines give bisacodyl a strong recommendation for short-term use (under four weeks) or as “rescue therapy” when gentler options haven’t worked. Senna received a conditional recommendation, meaning it works for many people but has weaker evidence behind it. Both can cause cramping, and using them daily for extended periods may lead to your colon becoming less responsive on its own. Think of stimulant laxatives as the tool you reach for when you’re uncomfortable now, not as your everyday strategy.
Skip the Stool Softeners
Docusate sodium (Colace) is one of the most commonly purchased constipation remedies, and it’s also one of the least effective. A comprehensive evidence review found that docusate is no more effective than a placebo for preventing or treating constipation. That held true across otherwise healthy adults, elderly patients, people with irritable bowel syndrome, and palliative care patients. In one study of patients already taking senna, adding docusate didn’t improve stool frequency or consistency at all. The patients on docusate actually needed more rescue laxatives. If you’re currently taking a stool softener and it doesn’t seem to be doing much, the evidence suggests you could stop without replacing it.
Fiber: The Overlooked First Step
Before reaching for any laxative, it’s worth checking whether you’re getting enough fiber. Current dietary guidelines recommend 14 grams of fiber for every 1,000 calories you eat, which works out to roughly 25 to 30 grams a day for most adults. The average American gets about half that. Fiber adds bulk to stool and draws water in, making it softer and easier to move through your system.
Psyllium husk (sold as Metamucil and generic equivalents) is the fiber supplement with the best evidence for constipation. It’s a bulk-forming laxative, meaning it absorbs water and expands in your gut, which triggers your colon to contract naturally. Start with a small dose and increase gradually over a week or two, because jumping straight to a full dose can cause gas and bloating. Drink plenty of water alongside it. Fiber without adequate fluid can actually make constipation worse.
Whole foods rich in fiber, like beans, lentils, oats, berries, and vegetables, accomplish the same thing and come with additional nutrients. But if your diet is low in fiber and you’re not ready to overhaul it overnight, a psyllium supplement bridges the gap effectively.
Prunes Actually Work
Prunes and prune juice aren’t just an old folk remedy. They contain sorbitol, a naturally occurring sugar alcohol that pulls water into the gut in the same way osmotic laxatives do. Prunes also provide fiber, so you’re getting two mechanisms in one food. For adults, four to eight ounces of prune juice per day or about six whole prunes is a reasonable starting dose. Some people find this gentler and more predictable than over-the-counter laxatives, and it’s a good option if you prefer to avoid medication altogether.
How to Choose Based on Your Situation
If constipation is new and you just need to get things moving once, a stimulant laxative like bisacodyl or a dose of magnesium citrate will work the fastest. If constipation keeps coming back, start with more fiber (from food or psyllium) and adequate water. If that’s not enough after a couple of weeks, add daily polyethylene glycol 3350. This layered approach matches what gastroenterologists generally recommend.
If you’ve tried over-the-counter options consistently for several weeks without improvement, prescription medications are available. Linaclotide, plecanatide, and prucalopride all received strong recommendations as second-line treatments. Your doctor can help determine which one fits your situation, particularly if there’s an underlying cause like slow gut motility or a pelvic floor issue that laxatives alone won’t fix.
Signs That Constipation Needs Urgent Attention
Most constipation is uncomfortable but not dangerous. It becomes an emergency when you haven’t had a bowel movement for a prolonged stretch and you’re also experiencing severe abdominal pain or major bloating. Other warning signs that warrant prompt medical evaluation include vomiting, blood in your stool, and unexplained weight loss. These symptoms can point to a bowel obstruction or another condition that won’t respond to laxatives.