Plain sparkling water does not cause systemic inflammation. No peer-reviewed research has linked the consumption of unflavored, unsweetened carbonated water to an increase in circulating inflammatory markers in healthy people. The concern likely arises from the fact that carbonation does produce temporary, localized effects in the mouth and digestive tract, and that the category of “sparkling water” now includes flavored and artificially sweetened products whose additives tell a more complicated story. The distinction between plain carbonated water and its flavored cousins matters enormously here.
What CO2 Actually Does in Your Mouth and Gut
The fizzy bite you feel when sipping sparkling water is not just a texture. Carbon dioxide dissolved in water reacts with an enzyme called carbonic anhydrase on the surface of your tongue, producing carbonic acid. That acid stimulates pain-sensing nerve fibers, which send signals to the brain that register as the familiar tingle. Researchers confirmed this mechanism by pretreating the tongue with a carbonic anhydrase inhibitor, which significantly reduced the neural response to carbonated water.1PubMed Central. Neurobiological and psychophysical mechanisms underlying the oral sensation produced by carbonated water This is technically a nociceptive response, meaning the body is registering the sensation through the same channels it uses for mild irritation, but that does not make it harmful. Many foods activate these nerve pathways; chili peppers and mustard are familiar examples.
Once the sparkling water reaches the stomach, the CO2 expands and the dissolved carbonic acid briefly lowers the local pH. A systematic review of carbonated beverages and digestive function found that drinking them causes a very short decline in esophageal pH.2PubMed. Systematic review: the effects of carbonated beverages on gastro-oesophageal reflux disease “Very short” is key: the drop is transient and self-correcting, and it falls well within the range the stomach is built to handle. The stomach’s own acid is far more potent than anything a glass of fizzy water introduces.
The Reflux Connection
Where sparkling water does have a measurable physical effect is on the valve between the esophagus and the stomach, known as the lower esophageal sphincter. When CO2 gas distends the stomach, this sphincter relaxes. One study found that all tested carbonated beverages produced a sustained reduction in sphincter strength of roughly 30 to 50 percent lasting about 20 minutes, while tap water caused no reduction at all. In about 60 percent of observations, the weakening was enough to bring the sphincter to a level that would normally be considered diagnostically incompetent.3PubMed. Response of the lower esophageal sphincter to gastric distention by carbonated beverages
A separate study in healthy volunteers confirmed this pattern: after drinking a carbonated beverage, the sphincter’s resting pressure dropped by more than half compared to baseline, and the frequency of transient sphincter relaxations rose sharply. Still water produced neither effect.4PubMed. Ingestion of a carbonated beverage decreases lower esophageal sphincter pressure and increases frequency of transient lower esophageal sphincter relaxation in normal subjects When that valve relaxes inappropriately, stomach acid can slip upward into the esophagus, and repeated acid exposure in the esophagus is a genuine source of tissue inflammation over time. But this is the mechanism behind acid reflux, not a systemic inflammatory response, and it matters that these sphincter changes were temporary. For someone without reflux disease, the occasional loosening of the valve after a glass of sparkling water is unlikely to cause lasting damage.
Bloating Is Not Inflammation
A lot of the perceived “inflammatory” effect of sparkling water is probably bloating being misidentified. When CO2 enters the stomach and begins to release gas, the stomach expands. That mechanical stretching can cause a feeling of pressure, fullness, and discomfort, especially if you drink more than about 300 milliliters at a time.5PubMed. Carbonated beverages and gastrointestinal system: between myth and reality This is a real sensation, and it can be unpleasant, but it is not an inflammatory process. No immune cells are being activated, no cytokines are being released, and no tissue is being damaged. The discomfort resolves as the gas is belched or absorbed.
Inflammation in the medical sense involves a cascade of immune activity: white blood cells migrate to a site, chemical signals like interleukins and tumor necrosis factor are released, and tissue may swell, redden, or become damaged. Bloating from gas distension shares the symptom of abdominal discomfort but none of the underlying biology. When wellness influencers describe sparkling water as “inflammatory,” they are almost certainly conflating these two very different things.
When Sparkling Water Genuinely Makes Things Worse
For people who already have a gastrointestinal condition, the picture shifts. A narrative review of fluid intake and functional GI disorders found that higher consumption of carbonated beverages was associated with worsening symptoms in gastroesophageal reflux disease, irritable bowel syndrome, and functional dyspepsia.6Caspian Journal of Clinical Cases. Fluid Intake and Functional Gastrointestinal Disease: A Narrative Review This makes intuitive sense given what we know about the sphincter relaxation and gastric distension effects.
The association with IBS is especially worth noting. A cross-sectional study of the general population found that higher intake of carbonated beverages was linked to irritable bowel syndrome overall, and that for the diarrhea-predominant subtype in particular, greater carbonated beverage consumption was associated with more severe symptoms.7PubMed Central. Diet in subjects with irritable bowel syndrome: a cross-sectional study in the general population IBS involves a dysfunctional gut-brain interaction, and the mechanical distension from gas may be enough to trigger or amplify pain signaling in an already hypersensitive gut. Again, the mechanism here is not classic systemic inflammation, but for someone with IBS or reflux, the practical effect is real discomfort and symptom flare-ups. If you have either condition and sparkling water seems to bother you, that is not a coincidence.
Flavored and Sweetened Sparkling Water Is a Different Story
The sparkling water aisle at any grocery store is stocked with products that contain citric acid, “natural flavors,” and sometimes artificial sweeteners. These additions change the health calculus considerably, and this is where inflammation concerns become more grounded in evidence.
Citric acid and other flavor-derived acids lower the pH of sparkling water well below the level of plain carbonated water. A study testing flavored sparkling waters found that all had pH values below the critical threshold for enamel erosion, and human enamel specimens showed significant, cumulative mass loss after just one day of immersion.8Brazilian Dental Science. The long-term effect of sparkling flavored water on human tooth enamel determined by gravimetric analysis: a preliminary evaluation While tooth enamel erosion is not the same as systemic inflammation, chronic exposure of oral tissues to acids can contribute to localized inflammatory conditions in the gums and mouth.
Artificial sweeteners pose a more directly inflammatory concern. A review of the evidence found that artificial sweeteners may induce changes in gut bacteria and gut wall immune reactivity, which could negatively affect people with or susceptible to chronic inflammatory conditions like inflammatory bowel disease.9PubMed Central. Artificial Sweeteners: History and New Concepts on Inflammation The gut microbiome plays a central role in regulating immune function, and disruptions to its composition have been linked to increased intestinal permeability and low-grade systemic inflammation. If your sparkling water contains sucralose, aspartame, or similar sweeteners, the inflammation question is no longer about the bubbles.
The Appetite and Ghrelin Puzzle
One area of research that sometimes gets folded into the inflammation discussion is the effect of carbonation on appetite hormones, because obesity and metabolic syndrome are themselves pro-inflammatory states. The evidence here is contradictory enough to be worth walking through.
A study in rats found that animals consuming carbonated beverages over about a year gained weight faster than those given degassed carbonated beverages or tap water. The researchers attributed this to elevated ghrelin, the hunger hormone, and found that in a parallel human study, ghrelin levels also rose in 20 healthy men after they drank carbonated beverages.10PubMed. Carbon dioxide in carbonated beverages induces ghrelin release and increased food consumption in male rats: Implications on the onset of obesity This generated alarming headlines, but the findings have not held up consistently across the literature.
A different human trial found the opposite effect for small meals: ghrelin levels were significantly lower after consuming a carbonated beverage compared to still water or a non-carbonated version of the same drink.11PubMed Central. The role of a pre-load beverage on gastric volume and food intake: comparison between non-caloric carbonated and non-carbonated beverage And a study in young women found that carbonated water increased feelings of fullness and decreased hunger ratings, with researchers concluding that the CO2-induced oral stimulation itself contributed to feelings of satiety.12Journal of Nutritional Science and Vitaminology. Oral Carbonation Attenuates Feeling of Hunger and Gastric Myoelectrical Activity in Young Women The evidence is messy enough that we cannot say carbonated water reliably increases or decreases appetite. The rat study involved carbonated beverages generally (not just plain water), over a very long period, and rat metabolism does not translate cleanly to human outcomes. The more cautious read is that carbonation’s effect on appetite and hunger hormones remains unsettled and probably small in the context of a normal diet.
Teeth and Bones
Two persistent fears deserve attention, even though they are not strictly about inflammation: the idea that sparkling water erodes your teeth and weakens your bones.
On teeth, plain sparkling water is only mildly acidic, with a pH typically between 3 and 4. While that is lower than still water, it is far less acidic than fruit juice, soda, or the flavored sparkling waters discussed earlier. Laboratory testing has shown that carbonated water can affect enamel microhardness, but the effect was minimal for carbonated water that contained calcium ions, suggesting mineral content plays a protective role.13PubMed Central. Effect of carbonated water manufactured by a soda carbonator on etched or sealed enamel In practice, drinking plain sparkling water with meals (when saliva production is highest and acts as a buffer) is unlikely to meaningfully harm your enamel. Sipping flavored acidic varieties throughout the day is another matter entirely.
On bones, the concern comes from studies linking cola consumption to lower bone mineral density, which people then extend to all carbonated beverages. This extrapolation is not supported by the evidence. A study of older women found that bone mineral density was not associated with intake of any type of carbonated beverage after adjusting for age, body weight, calcium intake, exercise, and other lifestyle factors. The researchers concluded that modest intake of carbonated beverages does not appear to have adverse effects on bone mineral density.14PubMed Central. Carbonated beverage consumption and bone mineral density among older women: the Rancho Bernardo Study The bone-density problem associated with cola likely stems from phosphoric acid, which is specific to cola formulations and absent from sparkling water.
Hydration Is Not Compromised
Another common worry is that the carbonation somehow interferes with hydration, and that chronic dehydration could promote inflammation. Two studies put this to rest fairly cleanly. One found that carbonated water did not alter overall gastric emptying of a meal, meaning the liquid moves through your system at the same rate whether it is fizzy or flat.15PubMed. Effect of carbonated water on gastric emptying and intragastric meal distribution Another tested carbonation specifically during exercise and found no effect on gastric emptying rate, concluding that carbonation does not change how quickly fluid leaves the stomach, even during submaximal physical activity. Subjects reported no difference in gastrointestinal comfort between carbonated and still water.16PubMed. Effects of drink carbonation on the gastric emptying characteristics of water and flavored water Sparkling water hydrates as effectively as still water. If the bubbles encourage you to drink more, they are helping, not hurting.
Mineral-Rich Sparkling Water and Metabolic Protection
An intriguing line of research suggests that certain naturally sparkling mineral waters, which tend to be rich in bicarbonate, magnesium, calcium, and potassium, may actually have metabolic benefits that cut against inflammation rather than promoting it. One animal study found that rats fed a high-fructose diet (designed to induce metabolic syndrome) showed reduced levels of triglycerides, insulin, and leptin when given a sodium-bicarbonate-rich naturally sparkling mineral water, compared to rats given regular tap water. The mineral water also helped preserve liver antioxidant activity that the fructose diet otherwise impaired.17PubMed Central. Relevance of a Hypersaline Sodium-Rich Naturally Sparkling Mineral Water to the Protection against Metabolic Syndrome Induction in Fructose-Fed Sprague-Dawley Rats: A Biochemical, Metabolic, and Redox Approach
This is a single animal study and should not be taken as proof that drinking mineral water prevents metabolic disease in humans. But it does highlight that the mineral content of different sparkling waters varies enormously, and that some mineral profiles could be metabolically favorable. European naturally sparkling waters, for instance, often contain hundreds of milligrams of bicarbonate per liter, which helps buffer acidity and may support alkaline balance. These are meaningfully different products from the carbonated tap water that comes out of a home soda maker.
Microplastics and Packaging
One source of genuine concern about inflammation from bottled sparkling water has nothing to do with the water itself and everything to do with the packaging. Research on polyethylene microplastics containing common packaging-related chemicals found that repeated exposure activated immune cells called macrophages, increased their production of reactive oxygen species, and enhanced secretion of the pro-inflammatory cytokine IL-1β by about 38 percent.18PubMed Central. Repeated exposure to polyethylene microplastic mixtures containing PFAS and bisphenols activates THP-1 macrophages with inflammatory features This was a cell-culture study, not a human trial, and the exposure conditions were controlled laboratory settings rather than what happens when you drink from a plastic bottle. Still, sparkling water stored in PET plastic bottles may contain microplastic particles, and the carbonation process itself (which involves pressurizing the container) could theoretically accelerate leaching. If you are trying to minimize potential inflammatory exposures, glass bottles or aluminum cans are a reasonable precaution, though the real-world magnitude of the microplastics risk from normal bottled water consumption remains uncertain.
Who Should and Shouldn’t Worry
If you are a generally healthy person drinking plain, unflavored sparkling water in normal quantities, the evidence does not support worrying about inflammation. The carbonation creates temporary physical effects, namely gas distension and brief sphincter relaxation, that resolve quickly and do not activate inflammatory pathways. Your bones, your hydration status, and your systemic inflammatory markers are not threatened by the bubbles.
The people who have legitimate reasons to be cautious are those with existing reflux disease, irritable bowel syndrome, or functional dyspepsia. For these groups, the mechanical effects of carbonation can amplify symptoms, and repeated symptom flares in conditions like GERD can involve genuine esophageal inflammation over time. If you fall into this category and notice that sparkling water worsens your symptoms, the evidence supports switching to still water rather than pushing through.
The biggest hidden risk is not the carbonation but what comes with it. Flavored sparkling waters with citric acid erode tooth enamel cumulatively over time. Artificially sweetened sparkling waters may affect gut bacteria and immune reactivity in ways that are still being studied. And bottled sparkling water in plastic packaging carries the same microplastic concerns as any other bottled beverage, with some theoretical reasons to think carbonation could make it slightly worse. Reading the ingredient list matters more than whether the water is fizzy.