Several over-the-counter options can help you have a bowel movement, ranging from fiber supplements that work within a day or two to stimulant laxatives that typically produce results in 6 to 12 hours. The right choice depends on how quickly you need relief and whether this is an occasional problem or a recurring one.
Foods That Help First
Before reaching for a supplement, certain foods have a genuine laxative effect. Prunes are the classic example, and they work because they contain sorbitol, a sugar alcohol that draws water into the intestines. Six prunes a day or four to eight ounces of prune juice is a reasonable starting dose for adults. Other high-sorbitol foods like pears, apples, and cherries can help too, though less dramatically.
Most adults fall well short of recommended fiber intake, which ranges from 22 to 28 grams per day for women and 28 to 34 grams for men depending on age. Beans, lentils, oats, berries, and vegetables like broccoli and Brussels sprouts can make a real difference when eaten consistently. Increasing fiber works best when paired with adequate water, roughly 1.5 to 2 liters per day.
Fiber Supplements (Bulk-Forming Laxatives)
If dietary changes alone aren’t enough, fiber supplements are the gentlest over-the-counter option. Products like psyllium (sold as Metamucil) and methylcellulose work by absorbing water in the intestines, making stool bulkier and softer so your colon can move it along more easily. A typical dose of psyllium is one teaspoon or one packet mixed into water, taken one to three times per day. Polycarbophil (sold as Fibercon) comes in tablet form, taken one to four times daily.
These take 12 hours to three days to produce a bowel movement, so they’re not the answer if you need fast relief. They’re best suited for people dealing with chronic or recurring constipation. One important rule: always drink a full glass of water with each dose. Without enough fluid, fiber supplements can actually make things worse by creating a dry, bulky mass in your intestines.
Osmotic Laxatives
Osmotic laxatives work by pulling water into your intestines, which softens stool and stimulates your colon to contract. The most widely used option is polyethylene glycol 3350 (sold as MiraLAX). The standard adult dose is 17 grams of powder dissolved in a glass of water, taken once daily. It generally takes one to three days to work.
Magnesium citrate is another osmotic option that acts faster, sometimes within 30 minutes to six hours. It comes as a liquid solution, and the adult dose is 6.5 to 10 fluid ounces, followed by a full glass of water. Because it pulls fluid into the gut more aggressively, it can cause cramping and loose stools. People with kidney disease or those on a magnesium-restricted diet should avoid it without medical guidance, since the body may not clear excess magnesium efficiently.
Stool Softeners
Stool softeners like docusate work differently from other laxatives. Rather than stimulating your intestines, they act like a detergent at the molecular level, helping water and fat mix into the stool so it comes out softer. They take 12 hours to three days to work and are among the mildest options available. Stool softeners are most useful when you want to avoid straining, for instance after surgery or during pregnancy, but they’re generally less effective than osmotic or stimulant laxatives for true constipation.
Stimulant Laxatives
When you need results relatively quickly, stimulant laxatives are the most reliable oral option. Senna (sold as Senokot and Ex-Lax) and bisacodyl (sold as Dulcolax) both work by directly triggering the nerves in your colon wall, causing it to contract and push stool forward. They also increase fluid secretion into the intestines. Senna typically produces a bowel movement in 6 to 12 hours, making a bedtime dose a common strategy for morning relief. The standard starting dose is two tablets once daily for adults.
These are effective but not meant for daily long-term use. One concern with chronic stimulant laxative use is a condition sometimes called “cathartic colon,” where the colon becomes dilated and loses its normal muscle tone. One analysis found that 45% of patients using stimulant laxatives more than three times per week for at least a year developed these changes on imaging. An older concern linking stimulant laxatives to colorectal cancer has not held up in more recent research and is considered unlikely.
Suppositories and Enemas
If you need the fastest possible relief, rectal options work in 15 minutes to one hour. Glycerin suppositories soften stool and gently stimulate the rectum. Bisacodyl also comes in suppository form for more direct stimulation. Fleet enemas use a saline solution to flush the lower colon. These bypass the digestive tract entirely, which is why they act so much faster than anything you swallow. They’re most useful for acute situations rather than ongoing management.
How to Choose the Right Option
Your timeline matters most. Here’s a practical breakdown:
- Need relief in under an hour: Suppositories or enemas
- Need relief overnight: Stimulant laxatives (senna or bisacodyl), taken before bed
- Can wait a day or two: Osmotic laxatives like polyethylene glycol, or magnesium citrate for a faster osmotic effect
- Dealing with ongoing constipation: Fiber supplements, dietary changes, and increased water intake as a daily routine
For a one-time problem, a stimulant laxative or magnesium citrate will likely do the job. For constipation that keeps coming back, fiber supplements and osmotic laxatives are safer for regular use. Stool softeners are the gentlest choice but also the least powerful.
Signs Something Else Is Going On
Occasional constipation is extremely common and usually harmless. But certain patterns suggest something beyond a simple backup. Rectal bleeding, unintentional weight loss, persistent abdominal pain, or constipation that doesn’t respond to any of the options above warrants a closer look from a healthcare provider. The same applies if your bowel habits change suddenly and significantly without an obvious explanation like travel, a new medication, or a dietary shift.