Several drinks can reliably help you have a bowel movement, and some work within hours. Prune juice is the most well-supported option, but coffee, magnesium-based drinks, kefir, and certain herbal teas all have evidence behind them. Which one to reach for depends on whether you need quick relief or a longer-term fix.
Prune Juice
Prune juice is the classic recommendation for a reason. It contains sorbitol, a natural sugar alcohol your body can’t fully absorb. Unabsorbed sorbitol draws water into the colon, softening stool and triggering movement. But sorbitol isn’t the whole story. Prune juice also contains pectin (a soluble fiber) and polyphenols, plant compounds that appear to work together with sorbitol to improve bowel function more than any single ingredient would alone.
In a randomized, placebo-controlled trial published in The American Journal of Gastroenterology, people with chronic constipation who drank prune juice daily for three weeks had significantly fewer hard stools and more normal-consistency bowel movements compared to the placebo group. An 8-ounce glass in the morning is a common starting point. Some people find warm prune juice works faster, though this hasn’t been formally tested. If you find the taste too sweet or heavy, diluting it with water still delivers the active compounds.
Coffee
Coffee stimulates your colon with a strength comparable to eating a meal. Caffeinated coffee increases colonic motor activity by about 60% more than water and 23% more than decaf. It triggers waves of pressure and coordinated contractions that push contents through the colon, which is why many people feel the urge to go within 20 to 30 minutes of their first cup.
Decaffeinated coffee also shows some stimulant effect on the colon, though the results in studies were less consistent. This suggests caffeine plays a role, but it isn’t the only factor. Compounds in coffee itself appear to promote the gastrocolic reflex, the signal your gut sends when something enters the stomach that tells the colon to make room. If you already drink coffee and it doesn’t seem to help, adding it on an empty stomach or pairing it with breakfast may amplify the effect.
Magnesium Citrate
Liquid magnesium citrate is an over-the-counter osmotic laxative, meaning it pulls water into the intestines to soften stool and stimulate contractions. It’s one of the fastest-acting options available without a prescription, generally producing a bowel movement within 30 minutes to 6 hours.
The standard adult dose is 6.5 to 10 fluid ounces, taken with a full 8-ounce glass of water. You can take it as a single dose or split it. This isn’t meant for daily use. It’s best reserved for occasional constipation when you need reliable, same-day results. People with kidney problems should be cautious, since the kidneys are responsible for clearing excess magnesium from the body and impaired function can lead to a dangerous buildup.
Kefir and Fermented Drinks
Kefir, a tangy fermented milk drink, contains a diverse mix of bacteria and yeasts that can influence gut function. In a pilot study of people with chronic constipation, daily kefir supplementation increased stool frequency, improved stool consistency, and accelerated the speed at which food moved through the colon. Participants also reduced their use of conventional laxatives during the study period.
Kefir won’t produce the dramatic, same-day effect of magnesium citrate. It works more gradually, making it a better fit if you’re dealing with ongoing sluggish digestion rather than an acute episode. Other fermented drinks like kombucha contain beneficial bacteria too, though they have less direct clinical evidence for constipation specifically. Look for kefir with live active cultures, and start with about one cup daily to see how your gut responds.
Senna Tea
Senna tea is a stimulant laxative available in most grocery stores and pharmacies. The active compounds, called sennosides, travel to the colon where gut bacteria convert them into a molecule that triggers two things: it speeds up transit through the colon, and it reduces water absorption from stool. The result is softer, faster-moving bowel contents. Most people feel the effects within 6 to 12 hours, which is why drinking a cup before bed often produces a morning bowel movement.
Senna is effective but not gentle. Cramping is common, especially at higher doses. It’s designed for short-term use. Using stimulant laxatives daily over long periods can make the colon less responsive on its own, creating a cycle of dependence. A few days of use to break a stubborn bout of constipation is reasonable, but if you need it regularly, that’s a sign something else is going on.
Warm Water and Hydration
You’ll find “drink more water” on nearly every constipation list, but the evidence is more nuanced than the advice suggests. Epidemiological studies consistently link low fluid intake with higher rates of constipation. However, research has not clearly shown that increasing fluids above a normal intake level fixes constipation in people who are already adequately hydrated. In other words, dehydration can cause constipation, but extra water on top of a normal intake probably won’t cure it.
That said, warm water first thing in the morning can stimulate the gastrocolic reflex on its own, and staying well-hydrated makes every other remedy on this list work better. Osmotic laxatives like magnesium citrate and sorbitol-containing drinks specifically need adequate water in your system to pull fluid into the colon. If you’re using any of these, drinking extra water alongside them isn’t optional.
Aloe Vera Juice
Aloe vera juice has a complicated reputation. The aloe plant’s latex layer contains anthraquinones, compounds with a strong laxative effect that work similarly to senna. However, the FDA ruled in 2002 that aloe is no longer generally recognized as safe and effective as a nonprescription laxative. Most commercial aloe juices sold today are “decolorized,” meaning the latex and its anthraquinones have been filtered out. The International Aloe Science Council recommends that oral aloe products contain less than 10 parts per million of aloin, the primary anthraquinone.
This means the aloe juice on store shelves likely has minimal laxative effect. Products that haven’t been decolorized may work but carry higher risk of side effects including cramping and diarrhea. With better-studied options available, aloe juice isn’t a first choice.
What Works Fastest vs. What Works Best Long-Term
If you need relief today, liquid magnesium citrate is the most predictable option, often working within a few hours. Coffee can also trigger a bowel movement quickly for many people. Senna tea typically takes overnight.
For ongoing or recurring constipation, daily prune juice and kefir offer gentler, sustainable support without the risks of stimulant laxatives. Combining a fermented drink with adequate hydration and a fiber-rich diet addresses the problem at its root rather than forcing a response from the colon.
If constipation doesn’t improve with these approaches, or if you notice blood in your stool, constant abdominal pain, inability to pass gas, vomiting, unexplained weight loss, or fever, those are signs of something beyond simple constipation that needs medical evaluation.