Sparkling water does not cause constipation. The available clinical evidence actually points in the opposite direction: carbonated water appears to improve bowel regularity. If you’re drinking plain sparkling water and staying well hydrated, the carbonation itself is not working against you. That said, a few details about what’s in your sparkling water and how your gut handles carbonation are worth understanding.
What Clinical Studies Actually Show
Two notable clinical trials have directly tested carbonated water’s effect on constipation, and both found it helpful. A study published in the European Journal of Gastroenterology and Hepatology measured constipation scores in participants drinking carbonated water versus tap water over several weeks. The carbonated water group saw their constipation scores drop significantly (from 16.0 to 12.1 on a standardized scale), while the tap water group showed no meaningful change.
A separate study focused on elderly stroke patients, a population especially prone to constipation. Patients who drank carbonated water had a significant increase in how often they had bowel movements and a decrease in constipation symptoms overall. The researchers concluded that carbonated water was an effective intervention for constipation in that group.
How Carbonation Affects Your Gut
When carbon dioxide is released from sparkling water in your stomach, it creates gas that gently distends the stomach wall. This distension stimulates nerves involved in digestion, which can increase the muscular contractions that move food through your digestive tract. Several studies have confirmed that sparkling water increases this gastric motility, essentially giving your digestive system a nudge to keep things moving.
Sparkling water also hydrates you just as effectively as still water. Since dehydration is one of the most common contributors to hard, difficult-to-pass stools, this matters. Your body absorbs the water the same way regardless of whether it was carbonated, so choosing sparkling over still won’t leave you any less hydrated.
Mineral Sparkling Water May Help Even More
Not all sparkling waters are nutritionally identical. Some natural mineral sparkling waters contain high levels of magnesium and sulfate, both of which have well-documented effects on bowel function. Magnesium draws water into the intestines (it’s the active ingredient in many over-the-counter laxatives), and sulfate increases stool bulk and softness. Water containing more than 1,000 mg/L of sulfate has been linked to a noticeable laxative effect.
A double-blind, placebo-controlled trial tested a magnesium-rich mineral water (1,000 mg/L magnesium, 2,000 mg/L sulfate) against a low-mineral sparkling water placebo. The mineral water significantly improved both stool frequency and consistency. Another trial found that even a moderately mineral-rich water (119 mg/L magnesium, 1,530 mg/L sulfate) reduced constipation in women when they drank about a liter daily. If you’re specifically looking for a constipation benefit, checking the mineral content on the label could make a difference. Most standard sparkling water brands have far lower mineral levels than the waters used in these studies.
When Sparkling Water Could Cause Digestive Discomfort
While sparkling water doesn’t cause constipation, it can cause bloating and gas. The carbon dioxide that stimulates digestion also takes up space, and some people feel uncomfortably full or gassy after drinking it. This bloating can sometimes create abdominal pressure that feels similar to constipation, even though stool movement isn’t actually slowed. For people with irritable bowel syndrome, Johns Hopkins Medicine recommends avoiding carbonated beverages altogether because the fizzy effect in the GI tract can worsen symptoms like bloating and abdominal pain.
The distinction here is between feeling bloated (a gas issue) and actually being constipated (a motility issue). If you notice abdominal discomfort after sparkling water but your bowel movements haven’t changed, the carbonation is likely just producing gas rather than affecting your regularity.
Flavored Sparkling Water Is a Different Story
Plain sparkling water and flavored or sweetened sparkling water are not the same product from a gut health perspective. Many flavored varieties contain artificial sweeteners like sucralose, acesulfame-K, or aspartame. These sweeteners can disrupt gut bacteria, creating an imbalance that shows up as bloating, abdominal pain, or changes in bowel habits, including constipation in some people. A study tracking 100 patients with inflammatory bowel disease found that those consuming artificial sweeteners experienced significantly more gastrointestinal symptoms than those who avoided them.
If you’re troubleshooting digestive issues and you drink flavored sparkling water regularly, the sweeteners are a more likely culprit than the carbonation. Check the ingredient list for sweeteners and try switching to plain sparkling water to see if your symptoms change. Also worth checking: sodium content. Some sparkling waters contain more sodium than you’d expect, and UChicago Medicine recommends looking for options with under 100 mg per can.
Why You Might Still Feel Backed Up
If you’re drinking sparkling water and experiencing constipation, the carbonation is almost certainly not the cause. More common explanations include not drinking enough total fluid (sparkling or otherwise), low fiber intake, lack of physical activity, or medication side effects. Some people also replace still water with sparkling water but end up drinking less overall because the carbonation makes them feel full faster. If that’s happening, you could be getting less total hydration than before, which would contribute to harder stools.
The simplest test is tracking your total fluid intake for a few days. If you’re consistently getting less than about 8 cups of fluid daily and your stools are hard or infrequent, increasing your overall water intake, sparkling or still, is the most straightforward fix.