The fastest way to trigger a bowel movement is with a rectal suppository or enema, which can work in as little as 10 to 15 minutes. But you have several options ranging from that kind of immediate relief down to techniques and drinks that work within a few hours, depending on what you have on hand and how urgently you need to go.
Suppositories and Enemas: 10 to 60 Minutes
If you need to go right now, a rectal approach is the fastest option available without a prescription. Stimulant suppositories (the most common brand is Dulcolax) typically produce a bowel movement within 10 to 45 minutes. They work by irritating the lining of the rectum, which triggers the muscles to contract and push stool out. Glycerin suppositories take a slightly different approach: they draw water into the intestine, softening the stool while also increasing pressure that prompts your intestinal muscles to move. You should expect a result within an hour.
Saline enemas (like Fleet) work on a similar timeline. You fill the rectum with liquid, which both softens stool and stretches the rectal wall to trigger the urge to go. Most people get results within 5 to 15 minutes. These are available at any pharmacy without a prescription.
Coffee: Within 4 Minutes for Some People
About 29% of people experience a strong urge to have a bowel movement after drinking coffee, and women are more likely to be in this group. A study published in the journal Gut found that among people who respond to coffee this way, colon activity increased within four minutes of drinking it and stayed elevated for at least 30 minutes. Interestingly, decaffeinated coffee triggered the same response, which means caffeine isn’t the only thing responsible. Coffee stimulates the gastrocolic reflex, a natural wave of contractions your colon makes in response to your stomach being stretched and stimulated.
If you already know coffee makes you need to go, a warm cup on an empty stomach is one of the simplest ways to get things moving quickly.
Milk of Magnesia: 30 Minutes to 6 Hours
Magnesium hydroxide, sold as Milk of Magnesia, is the fastest-acting oral laxative most people can buy over the counter. It pulls water into the intestines through osmosis, which softens stool and stimulates movement. It typically causes a bowel movement within 30 minutes to 6 hours. Take it with a full 8-ounce glass of water, since the mechanism depends on having enough fluid to draw into the gut. Many people take it at bedtime and wake up with results, but it can work much faster than that.
Prune Juice: A Few Hours
Prune juice contains sorbitol, a sugar alcohol that your body can’t fully absorb. It draws water into the colon the same way an osmotic laxative does, and prunes also contain fiber and compounds that stimulate intestinal contractions. For adults, four to eight ounces is a reasonable starting dose. Drinking it warm can speed things up slightly by adding the gastrocolic reflex on top of the sorbitol effect. Results typically come within a few hours, though this varies widely from person to person.
Senna: 6 to 12 Hours
Senna is a plant-based stimulant laxative available over the counter in tablets, liquids, and teas. It works by directly stimulating the nerves in your colon wall, forcing contractions that move stool along. The tradeoff for being gentle on the stomach is speed: it generally takes 6 to 12 hours to produce a bowel movement. That makes it a good option to take before bed if you want relief by morning, but not a great choice if you need to go in the next hour.
Physical Techniques That Help Right Now
If you’re sitting on the toilet and struggling, your body position may be working against you. When you sit on a standard toilet, the muscle that wraps around your rectum (like a sling) only partially relaxes, creating a kink that makes it harder to pass stool. When you squat, your hips flex enough to widen that angle from about 100 degrees to 126 degrees, which straightens the path and reduces the straining you need to do. You don’t need to squat on the toilet. A small footstool (like a Squatty Potty) that raises your knees above your hips achieves most of the same effect.
Abdominal self-massage can also help move things along, especially if you can feel stool is “right there” but won’t come out. The ILU technique follows the natural path of your large intestine:
- I stroke: Starting just under your left rib cage, stroke straight down toward your left hip bone. Repeat 10 times with gentle pressure.
- L stroke: Start below your right rib cage, move across your upper abdomen to the left, then down to your left hip. Repeat 10 times.
- U stroke: Start at your right hip, move up to your right rib cage, across to your left rib cage, then down to your left hip. Repeat 10 times.
Finish with small clockwise circles around your belly button for a minute or two. This traces the direction stool actually travels through your colon and can help push gas and stool toward the exit.
Preventing the Next Episode
Once you’ve solved the immediate problem, the goal is to keep it from happening again. Most Americans don’t eat enough fiber. The recommended amount is 14 grams for every 1,000 calories you eat, which works out to roughly 25 to 30 grams a day for most adults. Increasing fiber gradually (not all at once, or you’ll get painful gas) and drinking enough water are the two most effective long-term changes you can make. Regular physical activity also speeds up colon transit time, and simply going to the bathroom when you first feel the urge, rather than holding it, helps maintain the reflex over time.
When Constipation Is a Medical Emergency
Most constipation is uncomfortable but harmless. It becomes a medical emergency if you haven’t had a bowel movement for a prolonged time and you’re also experiencing severe abdominal pain or major bloating, which could signal a bowel obstruction. Vomiting alongside constipation, blood in your stool, or unexplained weight loss are also warning signs that need immediate medical attention.