Sodium bicarbonate is an antacid. It is officially classified as a safe and effective over-the-counter antacid ingredient by the FDA under 21 CFR Part 331, and it has been used to treat heartburn and sour stomach for well over a century. You probably know it better as baking soda, the same box sitting in most kitchen pantries. While it works fast, its short duration of action and high sodium content make it a less ideal choice for frequent or long-term use compared to other antacids.
How It Neutralizes Stomach Acid
When sodium bicarbonate hits the hydrochloric acid in your stomach, the two react almost instantaneously. The reaction produces water, salt, and carbon dioxide gas. That carbon dioxide is the reason you’ll likely burp shortly after taking it. The gas dissolves in the stomach’s liquid contents first and is only slowly released, so the belching may continue for several minutes.
This direct chemical neutralization is what makes it work so quickly but also what limits how long it lasts. Unlike antacids that coat the stomach lining or slowly dissolve over time, sodium bicarbonate is used up rapidly in the reaction. When taken by mouth, the neutralizing effect lasts only about 8 to 10 minutes before stomach acid production overwhelms it again. That’s considerably shorter than aluminum or magnesium-based antacids, which typically provide relief for 30 minutes to an hour or more.
Standard Dosage and Limits
The typical dose for heartburn relief is half a teaspoon of baking soda powder dissolved in a full glass of water, taken every two hours as needed. In tablet form, doses range from 325 milligrams to 2 grams, one to four times daily. Effervescent powder formulations use slightly larger amounts: 1 to 2.5 teaspoons in cold water after meals, with a daily maximum of 5 teaspoons.
The FDA sets strict daily caps based on age. Adults and children 12 and older should not exceed six half-teaspoon doses in 24 hours. Adults over 60 are limited to three half-teaspoon doses per day, reflecting slower kidney clearance in older adults. Children under 12 should not use sodium bicarbonate as an antacid at all.
One important detail from the product label: do not take it when your stomach is overly full from food or drink. A full stomach combined with the rapid carbon dioxide production can cause uncomfortable distension.
The Sodium Problem
The biggest practical concern with using baking soda as an antacid is how much sodium it delivers. A single teaspoon of baking soda contains roughly 1,260 milligrams of sodium. Even a half-teaspoon dose adds about 630 milligrams, which is more than a quarter of the 2,300-milligram daily limit recommended by most health guidelines. If you took six half-teaspoon doses in a day (the maximum allowed), you’d consume nearly 3,800 milligrams of sodium from the antacid alone, before counting anything you eat.
This makes sodium bicarbonate a poor choice for anyone on a sodium-restricted diet, anyone with high blood pressure, or anyone with heart failure or kidney disease. These conditions require careful sodium management, and even a few doses can push intake well beyond safe levels.
Risks of Overuse
Because baking soda is cheap, familiar, and available in every grocery store, people sometimes use it more casually than they would a product from the pharmacy aisle. That familiarity can lead to overuse, which carries real risks.
The most serious complication from chronic, excessive use is a condition called milk-alkali syndrome. It involves three simultaneous problems: dangerously elevated calcium levels, a shift in the blood’s pH toward overly alkaline, and acute kidney injury. Symptoms can start subtly with nausea, vomiting, constipation, increased thirst, and frequent urination. As it progresses, neurological symptoms appear: headache, dizziness, confusion, and in extreme cases with very high calcium levels, loss of consciousness. This syndrome is uncommon with occasional use but has been well documented in people who take baking soda regularly in large amounts.
Effects on Other Medications
Sodium bicarbonate changes the pH of your stomach, and that shift can alter how your body absorbs other medications. By raising gastric pH, it can actually increase the absorption of certain drugs that don’t dissolve well in acidic environments. This has been documented with some anti-inflammatory painkillers, certain diabetes medications, and blood thinners. In some cases, this means a drug hits your bloodstream faster or in higher amounts than expected.
If you take prescription medications regularly, the timing of a sodium bicarbonate dose matters. Spacing it at least two hours before or after other medications reduces the chance of an unwanted interaction.
How It Compares to Other Antacids
Sodium bicarbonate’s main advantage is speed. It starts working almost instantly, faster than chewable calcium carbonate tablets or liquid aluminum-magnesium formulations. But its 8-to-10-minute duration is its biggest weakness. Most people find the relief too brief to be practical, especially for ongoing heartburn.
Calcium carbonate (the active ingredient in products like Tums) provides a similar neutralizing reaction but lasts longer and doesn’t carry the same sodium load. Aluminum and magnesium hydroxide antacids work more slowly but sustain their effect over a longer period. For occasional, acute heartburn where you need fast relief and have nothing else available, baking soda works. For anything recurring, other antacids or acid-reducing medications are more practical options.
The bottom line: sodium bicarbonate is a legitimate, FDA-recognized antacid that neutralizes stomach acid on contact. It’s best suited for infrequent, short-term use in otherwise healthy adults who are mindful of the sodium content and dosage limits.