For most people dealing with constipation, an over-the-counter osmotic laxative or fiber supplement will get things moving within one to four days. The right choice depends on how long you’ve been constipated, how uncomfortable you are, and whether this is a one-time problem or a recurring pattern. Here’s what actually works and when to use each option.
Start With More Fiber and Water
Before reaching for any product, it’s worth checking whether your diet is the problem. Current guidelines recommend 14 grams of fiber for every 1,000 calories you eat daily, which works out to roughly 25 to 35 grams for most adults. The average American gets about half that. Increasing your intake of fruits, vegetables, beans, and whole grains can resolve mild constipation on its own, though it takes a few days to notice a difference.
If you can’t get enough fiber from food, a fiber supplement containing psyllium husk is the most common first step. Start with one teaspoon mixed into a full glass of water, and work up to one tablespoon up to three times a day as your body adjusts. The critical rule with psyllium: drink plenty of water alongside it. Psyllium absorbs liquid and forms a gel that adds bulk to your stool, making it easier to pass. Without enough water, it can actually make things worse and, in rare cases, cause a blockage.
Osmotic Laxatives for Reliable Relief
If fiber alone isn’t enough, osmotic laxatives are the most widely recommended next step. These work by pulling water into your intestines, softening the stool so it moves through more easily. The most common option is polyethylene glycol 3350 (sold as MiraLAX and store-brand equivalents). You mix a capful of powder into any beverage once daily.
Expect it to take two to four days before you have a bowel movement. That wait time frustrates people who want immediate relief, but osmotic laxatives are gentle and well-tolerated enough for daily use over longer stretches. They don’t cause the cramping that stronger options can, and they’re typically the first thing a doctor would suggest for ongoing constipation.
Magnesium Citrate
Magnesium citrate is another osmotic option that works faster and more aggressively. It’s sold as a liquid in bottles of roughly 200 to 300 mL, meant to be taken in a single dose or split across the day with a full glass of water. It usually produces results within a few hours. This makes it useful for more stubborn constipation, but the effect can be intense. Think of it as a step up in strength from polyethylene glycol, not a daily maintenance tool.
Stool Softeners: Do They Work?
Stool softeners containing docusate sodium (sold as Colace) are one of the most purchased constipation products, but their reputation has been mixed. They work by allowing water and fat to penetrate the stool, making it softer. For years, many clinicians considered them less effective than osmotic laxatives. However, a clinical trial comparing docusate directly to polyethylene glycol found the two performed similarly: about 67% of patients in the docusate group had a bowel movement within 72 hours compared to 71% in the polyethylene glycol group, with no meaningful difference in the time to first bowel movement (roughly 49 hours versus 45 hours). Side effects were comparable too, though polyethylene glycol caused loose stools more often (19% versus 10%).
Stool softeners are a reasonable choice if your constipation is mild or if you want to avoid straining, particularly after surgery or during pregnancy. They won’t provide fast relief for severe backup.
Stimulant Laxatives for Quick Results
When you need results sooner, stimulant laxatives are the strongest over-the-counter option. These contain ingredients like bisacodyl (Dulcolax) or senna (Senokot) that trigger the muscles of your intestinal wall to contract and push stool along. Oral tablets generally work overnight. Suppository forms work much faster, typically within 10 to 45 minutes, so use them only when you’re near a bathroom.
The trade-off is that stimulant laxatives commonly cause cramping and urgency. They’re meant for short-term use only. Don’t use bisacodyl for more than five consecutive days. Senna carries similar limits. Using stimulant laxatives regularly can make your bowels sluggish and dependent on them, turning occasional constipation into a chronic problem.
Choosing the Right Option
- Mild or occasional constipation: Increase fiber through food or a psyllium supplement. Drink more water. Give it two to three days.
- Moderate constipation lasting several days: Try polyethylene glycol 3350 daily. It’s gentle, effective, and safe for longer use.
- Uncomfortable but not urgent: A stool softener can help, especially if hard stools are the main issue.
- Need relief today: A bisacodyl suppository or magnesium citrate liquid will produce faster results, but expect some cramping.
You can also combine approaches. Taking a fiber supplement daily while using an osmotic laxative for a few days is a common strategy that addresses both the immediate problem and the underlying cause.
Lifestyle Changes That Make a Difference
What you take matters, but so does what you do. Physical activity stimulates the muscles that move food through your digestive tract. Even a 20-minute walk can help. Dehydration is one of the most common and overlooked causes of constipation, because your colon absorbs more water from stool when your body is low on fluids.
Timing matters too. Your colon is most active in the morning and after meals. Giving yourself unhurried time to sit on the toilet after breakfast, rather than rushing out the door, works with your body’s natural rhythms. A small footstool that raises your knees above your hips while sitting on the toilet can also help by straightening the angle of your rectum, making it physically easier to pass stool.
Signs of Something More Serious
Most constipation is uncomfortable but harmless. However, you should contact a healthcare provider if you notice blood in your stool, experience severe abdominal pain, or have constipation that persists beyond three weeks despite trying the options above. These can signal conditions that need evaluation beyond over-the-counter products. Sudden changes in bowel habits, especially after age 50, also warrant a conversation with your doctor.