Soda water can help with certain types of upset stomach, particularly indigestion and nausea, but it may make acid reflux worse. The answer depends on what’s actually causing your discomfort. Plain carbonated water has a long history as a folk remedy for digestive complaints, and a modest body of research supports some of those claims while raising caution flags for others.
What Carbonated Water Does Inside Your Stomach
When you drink soda water, dissolved carbon dioxide creates gas bubbles that expand in your stomach. This gentle distension changes how food distributes itself during digestion. In a study of healthy volunteers, carbonated water pushed a significantly greater proportion of both solids and liquids into the upper portion of the stomach compared to still water (74% vs. 56% for solids, 43% vs. 27% for liquids). Overall emptying speed stayed the same, but the internal rearrangement appears to be why many people feel temporary relief after a few sips.
Carbonated water also triggers a short-term increase in feelings of fullness and stimulates gastric activity. That satiating effect kicks in within minutes and lasts roughly 40 minutes. For someone dealing with nausea or a vague “off” feeling in their stomach, this mild stimulation can be enough to settle things down.
Evidence for Indigestion and Constipation
The strongest evidence comes from a controlled trial of patients with functional dyspepsia, the medical term for chronic indigestion with no identifiable structural cause. After drinking carbonated water regularly, participants’ dyspepsia scores dropped significantly (from 7.9 to 5.4 on a symptom scale), while those drinking tap water saw no improvement at all. The carbonated water group also experienced less early fullness, meaning they could eat more comfortably before feeling stuffed. Their early-satiety threshold jumped from 447 calories to 590 calories.
The same study found improvements in constipation and gallbladder emptying, suggesting carbonated water has a broader effect on digestive motility beyond just the stomach. If your upset stomach comes with sluggish digestion or a heavy, bloated feeling after meals, this is encouraging.
Nausea and Morning Sickness
Many people instinctively reach for something fizzy when they feel nauseous, and there’s a physiological basis for it. Carbonated water increases gastric activity and mildly stimulates the nervous system, both of which may counteract the queasy, stalled feeling that accompanies nausea. The effect is modest and short-lived, but for mild nausea it can be enough.
During pregnancy, some women find that small sips of sparkling water help with morning sickness. The carbonation may reduce the stomach’s overall acidity slightly, easing that rising, acidic sensation. The key is drinking slowly, since gulping carbonated water introduces a large volume of gas at once, which can make bloating worse and undo any benefit. Small, frequent sips work better than draining a full glass.
When Soda Water Can Make Things Worse
If your upset stomach involves heartburn or acid reflux, carbonated water is likely to backfire. A study using high-resolution pressure measurements found that a single 200 mL serving of a carbonated drink cut the pressure of the valve between the esophagus and stomach roughly in half, dropping it from a median of 40.5 mmHg to 18.5 mmHg. That valve, called the lower esophageal sphincter, is what keeps stomach acid from washing upward. When its pressure drops, acid escapes more easily.
The same study showed that carbonation dramatically increased the number of times that valve spontaneously relaxed: a median of 10.5 relaxation events after the carbonated drink, compared to just 1 after plain water and 0 at baseline. Each of those relaxations is an opportunity for acid to splash into the esophagus. So if your stomach discomfort is really a burning sensation behind the breastbone or a sour taste in the back of your throat, skip the soda water and stick with still.
Club Soda vs. Plain Sparkling Water
These aren’t identical drinks. Club soda contains added sodium bicarbonate and other minerals, while plain sparkling water (seltzer) is just water and carbon dioxide. Sodium bicarbonate is a mild antacid, the same compound found in baking soda. In club soda, the amount is small enough to provide a gentle buffering effect on stomach acid without the risks associated with spooning baking soda into your drink.
That distinction matters because concentrated baking soda, used as a home antacid remedy, carries real hazards. When large amounts of sodium bicarbonate meet stomach acid, the reaction produces a sudden surge of carbon dioxide gas. The FDA has flagged this risk after multiple case reports of gastric rupture. The trace amount in club soda is nowhere near dangerous, but it’s a good reason not to escalate from soda water to homemade baking soda solutions.
Sparkling water has a pH of about 5 to 6, making it only mildly acidic. Your stomach acid sits around pH 1.5 to 3.5. In practical terms, soda water is far less acidic than what’s already in your stomach, so it won’t meaningfully increase acidity on its own.
How to Get the Most Benefit
Choose plain sparkling water or club soda rather than flavored seltzers with citric acid, which can irritate an already sensitive stomach. Drink it chilled, since cold beverages tend to be more soothing for nausea. Sip slowly over 10 to 15 minutes rather than drinking quickly. Because carbonated water increases feelings of fullness, gulping it can leave you feeling uncomfortably distended, which is the opposite of what you’re going for.
If your upset stomach is from overeating or general indigestion, try 100 to 200 mL (roughly half to one cup) and wait. The effects on gastric activity peak within about 40 minutes. If it’s nausea without reflux, the same small amount sipped gradually tends to work best. And if the discomfort doesn’t improve or gets worse, that’s a signal the carbonation isn’t the right tool for whatever’s going on.
For children, the same general logic applies, but in smaller quantities. The fullness effect of carbonated water is pronounced enough that it can suppress appetite, which isn’t ideal for a child who’s already eating less because of a stomach bug. Small sips to help with nausea are reasonable, but plain water or an electrolyte solution remains the better choice for staying hydrated during illness.