Gaviscon and Tums both treat heartburn, but they work in fundamentally different ways, and that difference matters depending on what kind of relief you need. For occasional, mild heartburn, Tums is a simple and effective option. For reflux that happens after meals or while lying down, Gaviscon has a meaningful edge because it physically blocks acid from rising into your esophagus rather than just neutralizing it.
How They Work Differently
Tums is pure calcium carbonate. When you chew a tablet, the calcium carbonate reacts with stomach acid and neutralizes it on contact. This raises the pH in your stomach, which reduces the burning feeling. It’s straightforward chemistry: acid meets base, and the acid weakens. The relief is fast but temporary, because your stomach keeps producing acid.
Gaviscon contains an alginate (derived from seaweed) along with antacid ingredients. When it hits your stomach acid, three reactions happen simultaneously: the alginate transforms into a gel, sodium bicarbonate produces carbon dioxide bubbles, and calcium ions bind the gel together. The result is a foam “raft” that floats on top of your stomach contents. This raft acts as a physical lid, sitting right at the junction between your stomach and esophagus, blocking acid from splashing upward.
In other words, Tums reduces acid strength while Gaviscon physically prevents acid from going where it shouldn’t. Both approaches relieve heartburn, but they’re solving the problem at different points in the chain.
What the Clinical Evidence Shows
A randomized clinical trial comparing Gaviscon Advance to a standard non-alginate antacid found that Gaviscon was significantly better at suppressing what’s called the “acid pocket,” a pool of highly acidic fluid that forms on top of your meal and is the main driver of post-meal reflux. The antacid didn’t suppress this pocket. Gaviscon also reduced the amount of time acid spent in the esophagus, lowered symptom frequency, and improved symptom severity scores, while the standard antacid did not produce statistically significant improvements on those measures.
This study was conducted in obese individuals eating a late-night meal, which is essentially a worst-case scenario for reflux. The fact that Gaviscon outperformed a conventional antacid in that context is telling. The American College of Gastroenterology notes that studies on alginate preparations “suggest potential efficacy in symptom relief compared to other products,” though it also points out that alginate content varies between formulations sold in different countries. The UK version of Gaviscon (Gaviscon Advance) contains more alginate per dose than the US version, which matters for how well the raft forms.
When Gaviscon Has a Clear Advantage
Gaviscon pulls ahead in specific situations. If your heartburn kicks in after meals, especially large or late-night meals, the raft mechanism directly targets the problem. The raft floats on top of whatever you’ve eaten and blocks reflux episodes at the source. For best results, take liquid Gaviscon about 30 minutes after eating, which gives the meal time to settle and allows the raft to form on top of stomach contents.
Gaviscon also has a distinct benefit for a condition called laryngopharyngeal reflux (sometimes called silent reflux), where acid reaches the throat and voice box rather than just the lower esophagus. Alginates work against this through three mechanisms: the raft barrier, displacing the acid pocket, and binding pepsin and bile salts in the refluxed material. Pepsin is particularly damaging to throat tissue, and a standard antacid like Tums doesn’t address it.
Nighttime reflux is another scenario where Gaviscon tends to work better. When you lie down, gravity no longer keeps stomach acid in place, and a floating raft barrier provides protection that simple acid neutralization can’t match.
When Tums Makes More Sense
Tums is a better fit for quick, occasional heartburn that isn’t tied to meals or body position. If you eat something spicy and feel a burn 20 minutes later, a couple of Tums will neutralize excess acid within minutes. They’re small, portable, and don’t require measuring a liquid dose. For mild, infrequent heartburn, the simpler option is often the right one.
Tums also provides a meaningful dose of calcium, which some people factor into their supplement routine. Each tablet delivers 200 to 750 mg of calcium depending on the strength. This can be a plus for people concerned about bone health, though it also means you need to watch your total calcium intake from all sources.
Side Effects to Consider
Tums’ most notable side effect is acid rebound. Because calcium carbonate stimulates the stomach to produce a hormone called gastrin, your stomach may ramp up acid production after the antacid wears off, potentially making you feel worse than before you took it. This creates a cycle where you keep reaching for more tablets. Constipation is also common with regular use. In people who take large amounts over time, calcium can build up in the blood, leading to a condition called milk-alkali syndrome, which affects kidney function.
Gaviscon’s side effect profile is generally milder since the alginate itself is inert. The antacid components in Gaviscon (which vary by formulation but often include aluminum and magnesium compounds) can cause constipation or loose stools. The bigger concern with some Gaviscon formulations is sodium content, which can be significant. If you’re watching your sodium intake due to blood pressure or heart concerns, check the label carefully. Gaviscon Advance, for example, contains more sodium per dose than Tums.
US vs. UK Gaviscon: An Important Distinction
This is a detail many people miss. The Gaviscon sold in the United States has a different formula than the one sold in the United Kingdom and much of Europe. The UK version (Gaviscon Advance) contains substantially more sodium alginate, the ingredient responsible for raft formation. The US version contains less alginate and relies more heavily on its antacid components, making it behave more like a hybrid between a true alginate product and a standard antacid.
Most of the clinical research showing Gaviscon’s superiority over standard antacids used the UK formulation. If you want the full raft-forming benefit, the UK version (available online in the US) is the one backed by stronger evidence. The US version still works, but the difference in alginate concentration means the raft it produces may be less robust.
Choosing Based on Your Symptoms
- Post-meal heartburn or reflux: Gaviscon is the stronger choice, taken about 30 minutes after eating.
- Nighttime or lying-down reflux: Gaviscon’s raft mechanism provides a physical barrier that outperforms simple acid neutralization when gravity isn’t helping.
- Throat symptoms from reflux: Gaviscon’s ability to bind pepsin gives it an edge that Tums doesn’t have.
- Occasional, mild heartburn: Tums works fast and is convenient for sporadic symptoms not tied to meals.
- Pregnancy-related heartburn: Both are considered first-line options. The ACG guidelines list calcium-based antacids and alginates alongside each other as safe choices when lifestyle changes aren’t enough.
Neither product is designed for daily, long-term use. If you find yourself relying on either one most days of the week, that pattern itself is worth paying attention to, because frequent heartburn may point to a condition that benefits from a different class of treatment entirely.