Baking soda, or sodium bicarbonate, is commonly taken in doses of about half a teaspoon dissolved in water as a home antacid, while athletes use a much higher dose of roughly 0.3 grams per kilogram of body weight to buffer acid during intense exercise. Both uses carry real side effects, and the gap between a helpful dose and a harmful one is narrower than most people assume. Gastrointestinal complaints are almost universal at performance doses, and overdoing it at any dose can trigger dangerous metabolic shifts.
Doses Vary Widely Depending on Why You Are Taking It
The most common reason people reach for baking soda is heartburn or acid indigestion. For that purpose, the traditional home remedy is roughly half a teaspoon (about 3 grams) stirred into a glass of water, taken after meals. This is enough to neutralize a fair amount of stomach acid and typically brings quick relief. Many people repeat the dose once or twice during the day, though going beyond about seven half-teaspoon doses in 24 hours starts pushing into territory where side effects become more likely. If you are over 60, most guidance suggests keeping the dose even lower.
Athletes chasing a performance boost use a substantially larger amount. The dose that has been studied most is 0.3 grams per kilogram of body weight, which for a 70-kilogram person works out to about 21 grams, or roughly four teaspoons. That is seven times the typical antacid dose and is taken in one go, usually 60 to 90 minutes before exercise. This dose is meant to flood the blood with bicarbonate, raising its buffering capacity so muscles can work harder before acid buildup forces them to slow down.
For people with chronic kidney disease, doctors sometimes prescribe oral sodium bicarbonate tablets at lower daily doses, spread across the day, to correct low bicarbonate levels in the blood. The National Kidney Foundation has recommended oral alkali for patients whose serum bicarbonate drops below a certain threshold, and the prescribed dose is usually individualized based on blood work.
The Gastrointestinal Side Effects Are Hard to Avoid
Stomach and gut problems are the single most predictable consequence of taking baking soda, especially at athletic-performance doses. In one study where participants took 0.3 g/kg, nine out of ten experienced diarrhea, roughly two-thirds reported bloating and thirst, and nearly half felt nauseous. Average gut distress ratings on a 0-to-10 scale hit 5.1 after the bicarbonate dose, compared to just 0.5 after a placebo.
The timing of these symptoms matters if you are trying to work around them. Research tracking gastrointestinal complaints after a standard 0.3 g/kg dose found that symptoms peaked somewhere between 35 and 90 minutes after ingestion, depending on the study. One trial pinpointed the worst window at about 90 minutes post-dose, while another reported the peak closer to 35 to 50 minutes. The discrepancy likely comes down to whether the dose was taken as a solution, in capsules, or with food, all of which change how fast the bicarbonate reaches the small intestine.
At the lower antacid dose, gut problems are less dramatic but still common. Baking soda reacts with stomach acid to produce carbon dioxide, which causes belching and bloating. Taking it on a very full stomach compounds this, because the gas has less room to escape. If you have ever felt uncomfortably inflated after mixing baking soda with water and drinking it quickly, that carbon dioxide is the reason.
Why Timing and Delivery Method Matter
Athletes and researchers have experimented with several strategies to reduce gut distress without sacrificing the blood-alkalizing effect. Splitting the dose into smaller amounts taken over 30 to 60 minutes helps. Swallowing sodium bicarbonate in enteric-coated capsules, which dissolve in the intestine instead of the stomach, can also cut down on nausea and bloating. Mixing the powder into a small, carbohydrate-rich meal slows absorption and blunts the initial spike of gas in the stomach.
The goal with any of these approaches is to get blood bicarbonate levels high enough to matter without making yourself miserable in the process. Research from the International Society of Sports Nutrition notes that the ergogenic mechanism depends on raising extracellular pH enough to pull hydrogen ions and lactate out of working muscles faster, delaying the acidosis that causes fatigue. If the dose never fully absorbs because you vomit it up, the performance benefit evaporates. So finding a tolerable delivery strategy is not just a comfort issue; it determines whether the supplement actually works.
Serious Risks and Overdose
At home-remedy doses taken occasionally, baking soda is generally safe for most people. The danger zone starts when someone takes too much, too often, or for the wrong reason. Excessive ingestion can cause metabolic alkalosis, a condition where the blood becomes too basic. Symptoms range from muscle twitching and numbness to confusion, irregular heartbeat, and in extreme cases, seizures or cardiac arrest.
A review of 192 baking soda misuse cases reported to the California Poison Control System found that about 55% of callers had symptoms serious enough to warrant a medical evaluation, and 12 patients required hospital admission for electrolyte imbalances, metabolic alkalosis, or respiratory depression. The most common reason for misuse was using baking soda as an antacid, accounting for roughly 60% of cases. Other motivations included trying to pass a urine drug test and attempting to treat a urinary tract infection, neither of which baking soda actually accomplishes.
Potassium levels deserve special attention. Bicarbonate causes the body to shift potassium into cells, which can drop blood potassium dangerously low. Hypokalemia, as this is called, can trigger heart rhythm problems on its own, compounding the risk from alkalosis. People already taking diuretics or other medications that lower potassium are at higher risk.
Gastric Rupture Is Rare but Real
One of the more alarming risks that occasionally surfaces in medical literature is gastric rupture from baking soda ingestion. The mechanism is straightforward: when a large amount of sodium bicarbonate meets a stomach full of acid, the resulting carbon dioxide gas can expand the stomach beyond its limits. A review of the medical literature identified 10 reported cases of gastric rupture linked to baking soda ingestion going back to 1926, some involving people who had just eaten large meals and then consumed a significant quantity of baking soda to settle their stomachs. Two of those cases involved binge eating followed by bicarbonate use.
Ten cases across nearly a century of reporting suggests this is genuinely rare. But the cases that do occur tend to be catastrophic, often requiring emergency surgery. The practical lesson is simple: do not take large amounts of baking soda on a very full stomach, and do not use it to counteract the discomfort of eating an enormous meal.
Baking Soda for Athletic Performance
The sports science on sodium bicarbonate is extensive. The basic premise is that activities lasting roughly one to seven minutes at high intensity, where lactic acid accumulation is a primary limiter, benefit most from pre-exercise bicarbonate loading. Sprint cycling, rowing, swimming, and repeated high-intensity intervals are the classic use cases.
The mechanism is well-characterized. Raising blood bicarbonate levels increases the pH gradient between the inside and outside of muscle cells, which stimulates the transport of hydrogen ions and lactate out of the muscle. Research has confirmed that this leads to a delayed onset of intramuscular acidosis during exercise, allowing higher work rates before fatigue sets in. In practical terms, athletes report being able to sustain effort a few seconds longer or push through one or two additional reps.
An interesting wrinkle emerged from a meta-analysis examining whether combining sodium bicarbonate with beta-alanine, another popular buffering supplement, works better than either alone. Neither supplement in isolation produced a statistically significant performance improvement in that analysis, but the combination did, with a small but meaningful effect size. This suggests the two supplements may work through complementary pathways, with beta-alanine buffering acid inside the muscle and bicarbonate buffering acid outside it.
For endurance events lasting much longer than seven minutes, the evidence is weaker and more mixed. A systematic review examining exercise duration and sodium bicarbonate’s effects noted that while the supplement has been proposed as a performance enhancer by reducing acidosis, the benefit appears to shrink as exercise duration grows, likely because other fatigue mechanisms beyond acid accumulation take over.
Kidney Health and Chronic Kidney Disease
One of the more clinically significant uses of oral sodium bicarbonate is managing metabolic acidosis in people with chronic kidney disease. As kidney function declines, the kidneys lose their ability to excrete acid efficiently, and blood bicarbonate levels drop. This chronic low-grade acidosis accelerates kidney damage, breaks down muscle, and weakens bones. Correcting it with oral bicarbonate makes intuitive sense, and kidney guidelines have long recommended it for patients whose serum bicarbonate falls below a certain level.
A systematic review and meta-analysis of trials in CKD patients found that oral sodium bicarbonate significantly raised serum bicarbonate levels and appeared to slow the decline in kidney filtration rate compared to controls. The bicarbonate-treated group showed a meaningful preservation of kidney function, measured as a higher estimated filtration rate relative to the control group.
The picture is not perfectly clean, though. A well-designed, placebo-controlled multicenter trial specifically in patients with stage 3 and 4 CKD found no statistically significant difference in kidney filtration rate between the bicarbonate group and the placebo group at any time point during the study. That result tempers some of the enthusiasm from the pooled analyses, and it highlights the challenge of translating a plausible biological mechanism into a proven clinical benefit. The honest summary is that bicarbonate supplementation is a standard recommendation in CKD care, but the strength of evidence that it actually slows disease progression is still debated.
Uric Acid Kidney Stones
Alkalinizing the urine is one of the oldest and most effective medical strategies for dissolving uric acid kidney stones, and baking soda is one way to do it. Uric acid crystallizes readily in acidic urine but dissolves when the pH rises. Raising urinary pH from the 5.0-5.5 range, which is typical in people who form uric acid stones, to above 6.0 or 6.5 can dissolve existing stones without surgery.
A case series examining medical dissolution therapy for uric acid stones achieved complete stone dissolution in the vast majority of patients treated with alkalinizing agents. In one series, complete chemolysis was obtained in 88% of the 75 patients who had kidney stones at the start of treatment, driven mainly by increases in urine pH and citrate excretion.
That said, potassium citrate is generally the preferred alkalinizing agent for kidney stone prevention, not baking soda. The reason is practical: potassium citrate raises urine pH without adding sodium, whereas baking soda delivers a substantial sodium load that can increase calcium excretion in the urine and potentially promote calcium-based stones in susceptible people. Animal research has shown that sodium bicarbonate supplementation can increase urinary citrate and reduce urinary oxalate, both of which help prevent stone formation. But for most stone formers, a nephrologist or urologist will reach for potassium citrate first and reserve sodium bicarbonate for situations where potassium intake needs to be limited or citrate is not tolerated.
Blood Pressure and the Sodium Question
A teaspoon of baking soda contains over 1,200 milligrams of sodium, which is more than half the daily limit that most health organizations recommend. This naturally raises concern about blood pressure, particularly if you are taking it regularly. The relationship, however, is not as straightforward as you might expect.
An older but frequently cited crossover study compared sodium bicarbonate to sodium chloride (table salt) and found that while sodium chloride had no effect on blood pressure in either group, sodium bicarbonate actually decreased systolic blood pressure by about 5 mmHg in hypertensive subjects. This suggests that the anion paired with sodium matters. Chloride appears to be the more problematic partner when it comes to blood pressure, while bicarbonate may partially offset sodium’s pressor effects.
A more recent systematic review and meta-analysis specifically examined whether sodium bicarbonate raises blood pressure in people with chronic kidney disease, a population particularly sensitive to sodium loading. The review found no significant increase in systolic blood pressure across the included studies. In fact, patients on bicarbonate were not more likely to need additional blood pressure medication, and there was even a trend toward reduced antihypertensive use in the bicarbonate group.
This does not mean you should dismiss the sodium content entirely. People with congestive heart failure, severe hypertension, or conditions requiring strict sodium restriction should not self-prescribe baking soda without medical guidance. The reassuring blood pressure data come mostly from supervised clinical settings with monitored doses. Scooping baking soda out of a box every day for heartburn while also eating a high-sodium diet is a different scenario entirely.
Oral Health Uses
Baking soda shows up in toothpastes and mouthwash formulations, and there is some evidence behind these uses. As a mouth rinse, sodium bicarbonate solution significantly raises salivary pH, which shifts the oral environment away from the acidic conditions that promote tooth decay and favor harmful bacteria. A prospective study measuring the effects of a sodium bicarbonate oral rinse found meaningful increases in salivary pH after use.
In toothpaste, baking soda has been studied as an additive alongside fluoride. An in situ study comparing fluoride toothpaste with and without baking soda found that the combination of fluoride and sodium bicarbonate reduced enamel demineralization and increased remineralization compared to a placebo. However, the difference between fluoride-plus-baking-soda and fluoride alone was not statistically significant, suggesting that the fluoride is doing most of the heavy lifting. Baking soda’s contribution seems to be modest and additive rather than transformative.
One common worry is that baking soda is abrasive enough to damage enamel. In reality, its Mohs hardness is low compared to many commercial toothpaste abrasives, and it dissolves quickly in water, which limits the mechanical force it can exert on tooth surfaces. Using it as a paste directly on teeth every day is more aggressive than using a commercially formulated toothpaste that contains it as one ingredient among many, so moderation matters here.
Who Should Avoid Baking Soda Entirely
Several groups should steer clear of oral baking soda or use it only under direct medical supervision. People taking prescription medications that affect electrolyte balance, including certain diuretics, corticosteroids, and lithium, face compounded risks from the potassium and sodium shifts that bicarbonate causes. If you are already on a proton pump inhibitor or H2 blocker for chronic acid reflux, adding baking soda on top can push stomach pH too high and interfere with digestion and drug absorption.
Children present a particular concern. Their smaller body mass means a given spoonful of baking soda represents a much larger dose per kilogram than it would for an adult. The California Poison Control data included cases involving children as young as two months old, underscoring that baking soda should be kept out of reach just like any other supplement or medication.
Pregnant women are sometimes tempted to use baking soda for heartburn, which is almost universal in late pregnancy. While occasional small doses are unlikely to cause harm, the sodium load and the risk of alkalosis make it a poor first choice compared to calcium-based antacids or other options a doctor might recommend. The same goes for anyone on a sodium-restricted diet for heart failure, liver cirrhosis, or kidney disease: the sodium in baking soda adds up quickly and can worsen fluid retention.
Finally, a less obvious but important point: baking soda should not be taken within two hours of other oral medications. Because it changes stomach pH so rapidly, it can alter the absorption rate and effectiveness of many drugs, including aspirin, certain antibiotics, and iron supplements. If you take daily medications, spacing them well away from any baking soda dose is essential.