Heartburn is a burning sensation in your chest caused by stomach acid flowing backward into your esophagus, the tube that connects your mouth to your stomach. It affects 10 to 20% of adults in Western countries and is one of the most common digestive complaints. While occasional heartburn is usually harmless, frequent episodes can signal a more serious condition and, over time, damage the lining of your esophagus.
What’s Happening Inside Your Body
At the bottom of your esophagus sits a ring of muscle called the lower esophageal sphincter. Think of it as a one-way valve. It opens to let food drop into your stomach, then squeezes shut to keep acidic stomach contents from splashing back up. Under normal conditions, this muscle stays contracted at a steady resting pressure.
Heartburn happens when that valve relaxes at the wrong time. Your stomach produces hydrochloric acid to break down food, and when even a small amount escapes upward, it irritates the esophageal lining, which has no protective coating against acid. The result is that familiar burning feeling behind your breastbone.
The most common trigger for inappropriate relaxation is stomach distension. When your stomach stretches from a large meal or excess gas, it activates a reflex through the vagus nerve that briefly opens the sphincter. These relaxation episodes can last 10 to 45 seconds, which is long enough for acid to reach the esophagus. That’s why heartburn so often follows a big dinner.
Common Triggers and Foods
Certain foods directly weaken that muscular valve. Coffee, both regular and decaf, relaxes the lower esophageal sphincter. Chocolate contains a compound called methylxanthine (similar to caffeine) that does the same thing. Peppermint, garlic, and onions also cause the sphincter to loosen. Fatty, spicy, and fried foods are a double problem: they relax the valve and slow stomach emptying, which means food and acid sit in your stomach longer and have more opportunity to reflux.
Beyond food, several habits and situations make heartburn more likely. Eating within two hours of bedtime, bending over after meals, wearing tight clothing around the waist, smoking, and carrying extra weight around the midsection all increase pressure on the stomach or weaken the sphincter. Alcohol is another well-known trigger.
What Heartburn Feels Like
Typical heartburn produces a burning sensation in the chest, sometimes extending into the upper abdomen. It usually starts after eating or when you lie down or bend over. You may notice a sour or bitter taste in the back of your mouth, especially when lying flat, along with a feeling of food or liquid rising in your throat. Antacids typically provide quick relief, which is one of the clearest signals that acid reflux is the cause.
Heartburn can also wake you from sleep. Lying flat makes it easier for acid to travel up from the stomach, so nighttime episodes are common if you ate a late meal.
Heartburn vs. Heart Attack
Heartburn and heart attacks can feel remarkably similar. Even experienced physicians sometimes can’t distinguish them based on symptoms alone. Both can cause chest discomfort that comes and goes.
Heart attack pain tends to feel more like pressure, tightness, or squeezing rather than burning, and it often spreads to the neck, jaw, back, or arms. Other heart attack warning signs include shortness of breath, cold sweat, sudden dizziness, and unusual fatigue. Heartburn, by contrast, is closely tied to meals, responds to antacids, and often comes with that telltale sour taste. If you’re ever unsure whether your chest pain is heartburn or something cardiac, treat it as an emergency.
When Heartburn Becomes GERD
Everyone gets heartburn occasionally. It becomes gastroesophageal reflux disease (GERD) when episodes are frequent and severe enough to affect your daily life or damage your esophagus. Most clinicians look for symptoms occurring two or more times per week as a rough threshold, though there’s no single cutoff that applies to everyone.
GERD matters because chronic acid exposure causes real tissue damage. About 10% of people with untreated erosive inflammation of the esophagus develop strictures, which are areas of scarring and narrowing that make swallowing difficult. When chronic acid injury heals, the normal esophageal lining can be replaced by a different type of tissue in a process called Barrett’s esophagus. Barrett’s is significant because it carries a small but real increased risk of esophageal cancer, which is why people with this condition are monitored regularly.
Heartburn During Pregnancy
Pregnancy is one of the most common times for heartburn to appear, even in people who’ve never experienced it before. Rising levels of progesterone relax smooth muscle throughout the body, including the lower esophageal sphincter, reducing its ability to stay closed. As pregnancy progresses, the growing uterus also pushes upward on the stomach, increasing pressure on its contents. On top of that, the sphincter itself can shift into the chest cavity, where lower surrounding pressure makes it even easier for acid to escape. The combination of hormonal and physical changes means heartburn tends to get worse in the second and third trimesters.
Managing Heartburn at Night
Nighttime heartburn is particularly disruptive because it interrupts sleep and exposes the esophagus to acid for long stretches. Two positioning strategies make a measurable difference.
First, sleeping on your left side keeps the esophagus positioned above the stomach, making it harder for acid to flow upward. Sleeping on the right side does the opposite: it places the esophagus below the junction with the stomach, which promotes reflux and slows the time it takes for acid to clear. The American College of Gastroenterologists now recommends left-side sleeping as a lifestyle modification for GERD. Second, elevating the head of your bed (using a wedge pillow or blocks under the bedframe, not just stacking pillows) uses gravity to keep acid down. Combining left-side sleeping with head elevation appears to be the most effective approach for nighttime symptoms.
How Heartburn Medications Work
Heartburn treatments fall into three main categories, each working differently and on a different timeline.
- Antacids neutralize acid that’s already in your stomach. They work within minutes but wear off relatively quickly, making them best suited for occasional, immediate relief.
- H2 blockers reduce the amount of acid your stomach produces. They take about 60 minutes to start working but last 4 to 10 hours, which makes them useful for preventing symptoms you can anticipate, like after a meal you know will be a trigger.
- Proton pump inhibitors (PPIs) block acid production more completely than H2 blockers. They take longer to reach full effect, sometimes a few days, but provide the strongest and most sustained acid suppression. They’re typically used for frequent or persistent heartburn rather than the occasional episode.
For people who experience heartburn once in a while, antacids and the occasional H2 blocker are usually sufficient. If you find yourself reaching for these regularly, that pattern itself is worth paying attention to, as it may point toward GERD that benefits from a different treatment approach.
Lifestyle Changes That Help
Medications address the acid, but lifestyle adjustments target the underlying mechanics. Eating smaller meals reduces stomach distension, which is the primary trigger for inappropriate sphincter relaxation. Finishing your last meal at least two to three hours before bed gives your stomach time to empty before you lie flat. Losing weight, if you carry extra pounds around the midsection, reduces the physical pressure pushing stomach contents upward. Avoiding your personal trigger foods (the usual suspects are coffee, chocolate, fried foods, and alcohol, but everyone’s list is slightly different) can significantly reduce how often heartburn occurs.
These changes aren’t dramatic on their own, but they’re cumulative. Many people find that combining two or three of them reduces heartburn enough that they rarely need medication.