The fastest way to trigger a bowel movement is a bisacodyl suppository, which typically works within 10 to 15 minutes. If you’d rather not go that route, a glass of magnesium citrate can produce results in as little as 30 minutes. Beyond those two options, a handful of other strategies can get things moving within minutes to hours, depending on what’s causing the backup and what you have on hand.
Fastest Option: Suppositories
A bisacodyl suppository is the quickest over-the-counter remedy available. It works by directly stimulating the muscles in your lower colon, and onset is usually 10 to 15 minutes. You insert it rectally, lie on your side for a few minutes, and wait for the urge. It’s not the most comfortable experience, but when speed is the priority, nothing else comes close.
Magnesium Citrate: The Liquid Option
Magnesium citrate is a liquid osmotic laxative sold at most pharmacies. It works by pulling water into your intestines, which softens stool and triggers contractions. Onset ranges from 30 minutes to 6 hours, though many people notice effects on the faster end of that window. You drink it as a single dose or split it across the day, and it’s typically a one-time fix. Don’t use it for more than a week without medical guidance. Milk of magnesia (magnesium hydroxide) works through the same mechanism on a similar timeline.
Coffee and the Gastrocolic Reflex
If you’ve noticed that a cup of coffee sends you to the bathroom, that’s not a coincidence. Coffee stimulates the release of two hormones, gastrin and cholecystokinin, that trigger what’s called the gastrocolic reflex. This reflex tells your colon to start contracting and push waste toward the exit. For some people, this happens within minutes of the first sip. For others, it takes longer or doesn’t happen at all. Drinking coffee on an empty stomach, especially warm coffee, tends to produce the strongest effect. Even decaf has some stimulating properties, though regular coffee is more reliable.
Prunes and High-Sorbitol Foods
Prunes are one of the most effective food-based laxatives, and the reason goes beyond fiber. They contain 14.7 grams of sorbitol per 100 grams. Sorbitol is a sugar alcohol your body can’t fully absorb, so it draws water into the intestines, much like magnesium citrate does. As little as 5 grams of sorbitol can cause bloating, and 20 grams or more may cause cramping, so start with four or five prunes and see how your body responds. Prunes also contain both soluble and insoluble fiber, which helps keep things moving more regularly over time.
Other high-sorbitol options include pear juice, apple juice, and dried figs. These won’t work as fast as a suppository or magnesium citrate, but they can produce a bowel movement within a few hours and are gentler on your system.
Change Your Sitting Position
If you’re already on the toilet and struggling, raise your feet on a stool, a stack of books, or anything that brings your knees above your hips. This mimics a squatting position, which straightens out the final segment of your colon (the sigmoid colon), relaxes a key pelvic floor muscle, and widens the rectal canal. The result is a more direct path for stool to travel. It won’t create the urge to go on its own, but if you already feel something and can’t quite get it out, this simple adjustment can make a real difference.
Oral Stimulant Laxatives: Slower but Reliable
Senna and bisacodyl tablets are the two main stimulant laxatives available over the counter. Both work by increasing muscle contractions in your intestines. The trade-off for their reliability is time: oral bisacodyl takes 6 to 10 hours, and senna takes 6 to 12 hours. That makes them better as a “take it tonight, go in the morning” strategy than a quick fix. Many people take them at bedtime and wake up with the urge.
How Different Remedies Compare
- Bisacodyl suppository: 10 to 15 minutes
- Magnesium citrate or milk of magnesia: 30 minutes to 6 hours
- Coffee: minutes to hours (varies widely)
- Oral bisacodyl tablets: 6 to 10 hours
- Senna tablets: 6 to 12 hours
- Fiber supplements (psyllium): 12 to 24 hours
- Stool softeners (docusate): 24 to 48 hours
- Polyethylene glycol (MiraLAX): 24 to 48 hours
Stool softeners and bulk-forming fiber supplements are useful for prevention, but they won’t solve an immediate problem.
Why You Shouldn’t Rely on Fast Laxatives Regularly
Using stimulant laxatives or osmotic laxatives occasionally is fine. Using them frequently is not. Repeated use causes large losses of water and essential minerals that regulate nerve and muscle function, including your heart. The consequences of chronic laxative misuse include muscle weakness, numbness, seizures, irregular heartbeat, and in severe cases, cardiac arrest. Your colon can also become dependent on stimulant laxatives, making it harder to go without them over time.
If you’re reaching for laxatives more than once or twice a month, the better move is figuring out why you’re constipated. Common culprits include not drinking enough water, low fiber intake, inactivity, and certain medications (especially opioids, antacids, and some antidepressants).
Signs Something More Serious Is Going On
Ordinary constipation is uncomfortable but not dangerous. A few symptoms, however, signal something beyond a simple backup. Blood in your stool, unexplained weight loss, or a history of colon polyps all warrant a closer look. Severe abdominal pain paired with constipation can indicate a structural problem or irritable bowel syndrome.
Fecal impaction is a more urgent situation where hardened stool becomes stuck and won’t pass. Symptoms include nausea, vomiting, abdominal pain, and paradoxically, watery diarrhea or fecal leaking (liquid stool seeps around the blockage). Some people also experience urinary problems because the mass presses against the bladder. If you haven’t had a bowel movement in several days and notice these symptoms, that’s a situation that needs medical attention, not another laxative.