Gaviscon starts working within a few minutes of swallowing it. Unlike antacids that need to neutralize stomach acid chemically, Gaviscon forms a physical barrier almost immediately on contact with stomach acid. Each dose provides relief that lasts around 4 hours.
How Gaviscon Works So Quickly
Gaviscon’s speed comes from a simple physical reaction. The main ingredient, sodium alginate, is a seaweed extract that turns into an insoluble gel the moment it meets stomach acid. At the same time, bicarbonate in the formula reacts with the acid to produce tiny carbon dioxide bubbles. These bubbles get trapped inside the gel, making it float on top of your stomach contents like a raft.
This floating gel sits between the acid in your stomach and your esophagus, acting as a physical cap that prevents acid from splashing upward. Because the reaction happens on contact with acid rather than requiring absorption into your bloodstream, the protective raft forms within minutes of taking a dose. It stays in place for roughly 4 hours before gradually breaking down.
When to Take It for the Best Results
Timing matters more with Gaviscon than with many other heartburn remedies. The NHS recommends taking it after meals and at bedtime, because that’s when acid reflux tends to be worst. A typical dose is 10 to 20 ml of the liquid formula, up to 4 times a day.
Taking Gaviscon after eating is key because the raft needs stomach contents to float on. If you take it on an empty stomach, there’s less material for it to sit on top of, and the barrier won’t be as effective. Bedtime dosing is especially useful because lying down makes it easier for acid to flow back into the esophagus, and the raft helps block that.
Gaviscon Advance vs. Double Action
Not all Gaviscon products are the same, and the version you choose can affect how well it works. Gaviscon Advance contains 1,000 mg of sodium alginate per dose, which is twice the amount found in Gaviscon Double Action (500 mg). That higher alginate concentration produces a thicker, more robust raft, making Advance the preferred choice for people with frequent or more severe reflux.
Gaviscon Double Action compensates for its lower alginate content by including additional antacids like calcium carbonate and sodium bicarbonate. These neutralize acid directly while the raft forms, so you get two mechanisms of relief at once. Both versions start working within minutes, but Advance tends to be more effective specifically at preventing acid from reaching the esophagus, while Double Action may offer broader, lighter relief for occasional heartburn.
Spacing Gaviscon With Other Medications
If you take other medications, you need to leave a gap of at least 2 hours before or after taking Gaviscon. The raft and antacid ingredients can interfere with how your body absorbs certain drugs, including thyroid medication, iron supplements, some antibiotics, beta blockers, and steroids. This applies in both directions: don’t take Gaviscon within 2 hours before or after these medications.
Sodium and Mineral Content
If you’re watching your sodium intake for blood pressure or heart health, it’s worth knowing what’s in each dose. Regular strength Gaviscon liquid contains about 52 mg of sodium per tablespoon, while the extra strength version contains roughly 11 mg per teaspoon. For context, that’s a small fraction of the 2,300 mg daily limit most guidelines recommend, but it can add up if you’re taking multiple doses daily alongside a salt-restricted diet.
What to Expect Realistically
Most people feel noticeable relief within 5 to 10 minutes of taking Gaviscon. The burning sensation in your chest or throat should ease as the raft blocks acid from rising. If you’re using it for the first time, keep in mind that the 4-hour window is an average. Eating a large meal, drinking carbonated beverages, or lying down immediately can all shorten how long the raft stays effective.
Gaviscon works best for occasional reflux or as a complement to other treatments. If you find yourself reaching for it every day for more than two weeks without improvement, that’s a sign your reflux may need a different approach, such as a proton pump inhibitor that reduces acid production at the source rather than just blocking it physically.