Gaviscon and Maalox are not the same product. While both are sold as over-the-counter heartburn remedies, they contain different active ingredients and work in fundamentally different ways. Gaviscon forms a physical barrier on top of your stomach contents to block acid from rising into your esophagus, while Maalox chemically neutralizes the acid itself. This distinction matters because it affects how long each one works, when you should take it, and which one suits your specific symptoms better.
How the Active Ingredients Differ
Gaviscon’s key ingredient is alginic acid (or sodium alginate), paired with antacid compounds like aluminum hydroxide and magnesium carbonate. Maalox contains aluminum hydroxide, magnesium hydroxide, and simethicone. The overlap in aluminum-based compounds is where the confusion starts, but the presence of alginate in Gaviscon and simethicone in Maalox sets them apart.
Simethicone, the extra ingredient in Maalox, is an anti-gas agent. It breaks up gas bubbles in your stomach and intestines, which is why Maalox is often marketed for both heartburn and bloating. Gaviscon doesn’t contain simethicone and doesn’t target gas at all.
They Work in Completely Different Ways
The biggest difference between these two products isn’t on the label. It’s what happens after you swallow them.
Maalox is a classic antacid. The aluminum hydroxide and magnesium hydroxide combine with stomach acid and neutralize it directly. This raises the pH in your stomach, reducing the burning sensation. The relief is fast but relatively short-lived, typically lasting a couple of hours before acid levels return to normal.
Gaviscon does something unique. When the alginate in Gaviscon meets stomach acid, it reacts with the bicarbonate in the formula to create a foamy, gel-like raft that floats on top of your stomach contents. This raft acts as a physical lid, sitting between the acidic pool in your stomach and the opening to your esophagus. During reflux episodes, the raft either blocks stomach contents from rising or moves into the esophagus ahead of the acid, shielding the sensitive tissue. One dose of Gaviscon provides relief for about four hours, according to the NHS.
This raft-forming action makes Gaviscon particularly well-suited for acid reflux and regurgitation, where the problem isn’t just too much acid but acid ending up in the wrong place. Maalox, by contrast, simply lowers the overall acid level in your stomach.
Which One to Choose for Your Symptoms
If your main complaint is heartburn with a sour taste in the back of your throat, or if you frequently feel stomach contents coming back up (especially after meals or when lying down), Gaviscon’s barrier approach targets that problem more directly. Its raft sits right at the junction where acid escapes into the esophagus.
If your issue is more of a generalized burning in the stomach, or if you’re dealing with both indigestion and gassiness, Maalox may be the better fit. The combination of acid-neutralizing compounds plus the anti-gas agent addresses both symptoms at once. Maalox also tends to work faster since it’s chemically neutralizing acid on contact rather than waiting for a raft to form.
For occasional, mild heartburn with no reflux component, either product will help. The practical difference becomes more meaningful when symptoms are frequent or when reflux (not just acid) is the core problem.
When and How to Take Each One
Gaviscon works best when taken after meals and at bedtime. The NHS recommends 10 to 20 ml up to four times a day at those times. Taking it after eating is important because the raft needs to form on top of a full stomach to create an effective barrier. If you take it on an empty stomach, there’s nothing for the raft to sit on.
Maalox is also typically taken after meals or whenever symptoms appear. Because it neutralizes acid directly rather than forming a barrier, the timing is less critical. You can take it when you feel the burn and expect relatively quick relief.
Sodium and Kidney Considerations
Gaviscon contains sodium, which is worth knowing if you’re watching your salt intake. Regular-strength Gaviscon liquid has about 52 mg of sodium per tablespoon dose. The extra-strength version is lower at 11 mg per teaspoon. These amounts are modest compared to dietary sodium, but they can add up over multiple daily doses for people on strict sodium restrictions.
Both products contain aluminum and magnesium compounds, and both carry warnings for people with kidney problems. Healthy kidneys clear these minerals without trouble, but impaired kidneys can allow aluminum and magnesium to accumulate in the blood. Long-term use at high doses in people with kidney disease has been linked to serious complications, including a type of anemia and, in rare cases, neurological effects. People with significant kidney disease should avoid prolonged use of either product.
Formulation Variations Add Confusion
Part of the reason people wonder whether these products are interchangeable is that both brands sell multiple versions with overlapping ingredient profiles. Maalox comes in regular strength (200 mg each of magnesium hydroxide and aluminum hydroxide with 20 mg simethicone per dose) and extra strength (400 mg of each antacid with 40 mg simethicone). Gaviscon sells regular and extra-strength versions with varying concentrations of alginate and antacid compounds.
In some countries, the formulations differ even more. Gaviscon Advance, widely sold in the UK, contains a higher concentration of alginate and is specifically designed to maximize the raft-forming effect. The US version of Gaviscon leans more heavily on its antacid components. So a bottle of Gaviscon in London and a bottle in New York may not be identical, even though they share a name. Always check the active ingredients on your specific product rather than assuming the formula is the same everywhere.
The bottom line: Gaviscon and Maalox treat overlapping symptoms but through genuinely different mechanisms. Maalox neutralizes acid. Gaviscon blocks it from reaching your esophagus. They’re not interchangeable, and choosing between them depends on whether your problem is too much acid or acid in the wrong place.