You’re staring at that empty can of LaCroix or Topo Chico, wondering why things feel a bit... stuck. It’s a common worry. You’ve probably heard some "wellness guru" on TikTok claim that the bubbles in your sparkling water are basically turning your intestines into a desert. Or maybe your aunt told you that carbonation wrecks your digestion.
But does seltzer cause constipation?
Honestly, the answer isn't a simple yes or no, but for most people, it's a resounding "no." In fact, for a lot of folks, seltzer might actually help you go. It sounds counterintuitive, I know. How can something that feels like it’s filling you with air help move things along? We need to look at the actual science of carbonation, hydration, and how your gut reacts to those tiny little bubbles.
The Gas Factor: Why Seltzer Feels Like It’s Causing Problems
The big reason people think seltzer causes constipation is the bloat. Carbonated water is infused with carbon dioxide ($CO_2$) gas under pressure. When you drink it, that gas has to go somewhere. Some of it comes back up as a burp. Some of it travels down.
If you already have a "lazy" gut or suffer from something like Irritable Bowel Syndrome (IBS), that extra gas can feel like a traffic jam in your colon. It creates pressure. It makes you feel full and distended. Because you feel bloated, your brain associates that discomfort with being backed up.
But feeling bloated isn't the same thing as being constipated.
Constipation is technically defined by the frequency and consistency of your stool—usually fewer than three bowel movements a week or passing hard, dry lumps. Seltzer doesn't inherently dry out your stool. If anything, it’s doing the opposite because, at its core, seltzer is just water.
🔗 Read more: Robert Wadlow and the Science of the 10 Feet Tall Man: What Biology Actually Allows
What the Research Actually Says
Back in 2002, a study published in the journal European Journal of Gastroenterology & Hepatology looked at people with functional dyspepsia and chronic constipation. They split them into two groups: one drank still water, and the other drank carbonated water for two weeks.
The results were kind of shocking to the "seltzer is bad" crowd.
The carbonated water group actually showed significant improvement in both their digestion and their constipation compared to the still water group. The bubbles seemed to stimulate the digestive tract. It’s like the carbonation acts as a tiny, internal massage for your intestines, encouraging peristalsis—the muscle contractions that move waste toward the exit.
When Sparkling Water Actually Becomes a Problem
Now, I'm not saying you should go out and chug a gallon of Perrier if you're feeling stopped up. There are specific scenarios where seltzer might actually make things worse for you personally.
It often comes down to what else is in the can.
The Additive Trap
If you aren't drinking "plain" seltzer, you might be ingesting artificial sweeteners. Ingredients like sorbitol, erythritol, or xylitol are notorious for causing digestive distress. While these often cause diarrhea (the "sugar-free gummy bear" effect), in some people, they can cause such intense bloating and gas that the normal movement of the gut gets thrown out of whack.
The "Air Swallowing" Issue
If you’re chugging your seltzer quickly, you aren't just getting the $CO_2$ from the drink. You're swallowing atmospheric air. This leads to aerophagia. Too much air in the system can slow down the transit of food because the intestines are busy dealing with gas pockets rather than moving solids.
The Temperature Factor
Ice-cold drinks can sometimes cause a temporary "shock" to the digestive system in sensitive individuals. If your gut is already prone to spasms, a freezing cold carbonated beverage might cause the muscles to tighten up, making it feel harder to pass stool.
Seltzer vs. Mineral Water vs. Tonic Water
We tend to group all "fizzy waters" together, but they are totally different beasts when it comes to your bathroom habits.
- Seltzer: Just water and $CO_2$. Usually totally fine.
- Club Soda: Water, $CO_2$, and added minerals like sodium bicarbonate or potassium sulfate. These minerals can actually be slightly alkaline, which might help some people's stomach acid levels, potentially aiding digestion.
- Mineral Water: Naturally carbonated from a spring. These often contain high levels of magnesium. Magnesium is a natural osmotic laxative. It draws water into the bowels. If you’re drinking something like Gerolsteiner, you might find it actually helps you stay regular because of that mineral content.
- Tonic Water: This is essentially soda. It’s loaded with sugar (or high fructose corn syrup) and quinine. Sugar is a major trigger for gut inflammation and can definitely contribute to constipation in high amounts.
If you think your "seltzer" is causing issues, check the label. If it says "tonic" or has 30 grams of sugar, that’s your culprit, not the bubbles.
The Dehydration Myth
There’s this persistent myth that carbonated water is dehydrating. The idea is that the bubbles somehow "leach" water from your body or that the acidity makes you pee more.
This is just wrong.
A study from St. Andrews University in Scotland compared the hydration levels of different beverages. They found that sparkling water was just as hydrating as still water. Since dehydration is the number one cause of constipation—your colon sucks water out of your waste when you’re low on fluids, making it hard and dry—drinking seltzer is actually a preventative measure.
If you hate the taste of plain water and seltzer is the only way you get your fluids in, keep drinking it. Being hydrated on seltzer is a million times better for your poop than being dehydrated because you find tap water "boring."
Does Seltzer Cause Constipation via Acid Reflux?
There is a weird, indirect link here. Seltzer is slightly acidic ($CO_2$ turns into carbonic acid when dissolved in water). For people with GERD or severe acid reflux, seltzer can trigger flare-ups.
When you have bad reflux, you might change your eating habits. You might eat less fiber, move less, or take more antacids. Calcium-based antacids (like Tums) are famous for causing constipation.
So, does seltzer cause constipation directly? No. But if it makes your heartburn so bad that you start popping Tums like candy, then yeah, you’re going to get backed up. It’s a secondary effect, but it’s worth noting if you have a sensitive esophagus.
Practical Steps to Keep Things Moving
If you love your bubbles but feel like your digestion is sluggish, you don't necessarily have to quit the fizz. You just need to be smarter about how you consume it.
- Watch the "Natural Flavors": Some people are sensitive to the chemical blends used for flavoring. Try switching to a plain seltzer and squeezing in a real lime or lemon.
- Slow Down: Don't chug. Sip. Give your body time to process the gas so it doesn't get trapped in your small intestine.
- Check Your Magnesium: If you are prone to constipation, try a mineral-heavy sparkling water. Look for brands with higher magnesium content on the back label.
- The 2:1 Rule: If you’re worried, try drinking two glasses of still water for every one can of seltzer. This ensures you’re getting pure hydration without the cumulative gas load.
- Move Your Body: If you feel "bubbly" and stuck, a 10-minute walk is usually enough to help the gas pass and get your bowels stimulated.
The Bottom Line on Bubbles
Seltzer doesn't cause constipation for the general population. In many clinical cases, it actually helps treat it by stimulating the nerves in the mouth and throat that trigger the digestive "start" signal. It also keeps you hydrated, which is the most important factor for gut health.
If you feel like you’re the exception to the rule, look at your additives. Check for "Stevia," "Xylitol," or "Sucralose." These are much more likely to be the villains in your digestive drama than the carbonation itself.
If you are genuinely struggling with chronic constipation, the best move is to track your fiber intake and daily movement. Seltzer is a convenient scapegoat, but it's rarely the actual reason you can't go.
What to Do Next
- Switch to plain, unflavored sparkling water for three days to see if the bloating subsides.
- Increase your daily fiber intake to at least 25-30 grams while maintaining your seltzer habit to see if the "stuck" feeling is actually just a lack of bulk in your diet.
- Note the timing. If you feel constipated only after drinking seltzer on an empty stomach, try having it with a meal to buffer the effects of the gas on your digestive tract.
- Consult a gastroenterologist if you experience pain, blood, or go more than a week without a bowel movement, regardless of what you're drinking.