Heartburn is a burning sensation in the middle of your chest, caused by stomach acid flowing backward into the esophagus. It can range from a mild warmth behind your breastbone to a sharp, intense pain that radiates up toward your throat. A typical episode lasts two hours or longer, depending on what triggered it.
The Core Sensation
The hallmark of heartburn is a burning feeling that starts in the upper abdomen or lower chest and rises upward. Most people describe it as acid burning from the inside, centered behind the breastbone. The intensity varies widely. After a mildly spicy meal, you might feel a low-grade warmth that fades once the food is digested. After a large, fatty dinner followed by lying on the couch, the sensation can escalate into something that feels more like pressure or tightening across the chest.
That tightening quality is worth noting because it can mimic the squeezing sensation of a heart problem. Many people who experience heartburn for the first time assume something is wrong with their heart, which is understandable given the location of the pain.
What Happens Inside Your Body
Your esophagus connects your mouth to your stomach, and at the bottom of it sits a ring of muscle that acts like a one-way valve. This valve opens to let food into the stomach and then closes to keep everything down. Heartburn happens when this valve weakens or relaxes at the wrong time, allowing stomach acid to splash upward into the esophagus.
Your stomach has a protective lining designed to handle acid. Your esophagus does not. When acid touches the unprotected esophageal tissue, it irritates the nerve endings there, producing that characteristic burn. Certain foods, medications, and even stress can cause the valve to relax inappropriately. A hiatal hernia, where part of the stomach pushes up through the diaphragm, can also impair the valve’s ability to stay shut.
Why It Gets Worse at Night
Gravity plays a bigger role in heartburn than most people realize. When you’re standing or sitting upright, gravity helps keep stomach contents where they belong. The moment you lie flat, your throat and stomach are at roughly the same level, and acid flows into the esophagus much more easily. This is why heartburn often strikes at bedtime or wakes people in the middle of the night.
Bending over has a similar effect. Leaning forward to tie your shoes, pick something up, or exercise shortly after eating can push acid upward and trigger a flare. If you notice your symptoms peak within an hour or two of eating, the combination of a full stomach and a position change is likely the cause.
Symptoms Beyond the Burn
Heartburn doesn’t always stop at a burning chest. Many people notice a sour or acidic taste in the back of their mouth, especially during more severe episodes. This happens because the acid physically reaches the upper esophagus or throat. In some cases, the body responds with a reflex that floods the mouth with saliva. This reaction, called water brash, can produce up to two teaspoons of saliva per minute and leaves a feeling of liquid stuck in the back of the throat mixed with that unmistakable sour taste.
Other common companions to the burn include a sensation of food sitting in the middle of your chest, a lump-in-the-throat feeling, a hoarse voice (particularly in the morning), and a dry cough that doesn’t seem connected to a cold. Some people also experience mild nausea, especially when the reflux is severe.
Heartburn vs. Heart Attack
The overlap between heartburn and cardiac chest pain is real, and it’s the reason this question matters. Here are the practical differences:
- Timing: Heartburn usually occurs after eating, while lying down, or while bending over. Heart attack pain is more often triggered by physical exertion or stress and can strike at any time.
- Character of pain: Heartburn is primarily a burning sensation. Heart attack pain tends to feel like crushing pressure, tightness, or squeezing that may spread to the arms, neck, jaw, or back.
- Response to antacids: Heartburn typically improves within minutes of taking an antacid. Cardiac pain does not.
- Breathing: Heart attacks often come with shortness of breath, dizziness, or a cold sweat. Heartburn rarely causes any of these.
If your chest pain is sudden, feels like intense pressure, radiates to your arm or jaw, or comes with difficulty breathing, treat it as a cardiac emergency regardless of whether you recently ate.
How Long an Episode Lasts
Mild heartburn triggered by a specific food often resolves once that food has been digested, typically within a couple of hours. More persistent episodes, especially those fueled by a large meal, alcohol, or lying down too soon after eating, can linger for two hours or more. Nighttime heartburn tends to last longer simply because your sleeping position keeps the acid in contact with the esophagus.
Over-the-counter antacids that neutralize acid directly can bring relief within minutes. Another class of medication, H2 blockers, works differently by reducing the amount of acid your stomach produces. These take about an hour to ease symptoms but can also be taken 30 to 60 minutes before a meal you know will cause trouble. Proton pump inhibitors are the strongest option, but they’re designed for daily use over days or weeks rather than quick rescue during an episode.
Signs That Something More Serious Is Happening
Occasional heartburn after a heavy meal is common and not a cause for concern on its own. But frequent heartburn, defined as two or more episodes per week, can damage the esophagus over time. Certain symptoms signal that the problem has moved beyond routine reflux:
- Difficulty swallowing or pain while swallowing: This can indicate narrowing or inflammation of the esophagus.
- Unexplained weight loss or persistent loss of appetite.
- Persistent vomiting, especially vomit that contains blood or looks like coffee grounds.
- Black or tarry stools, which suggest bleeding somewhere in the digestive tract.
Any of these symptoms alongside regular heartburn warrants a medical evaluation to rule out complications like esophageal damage or other conditions that can mimic reflux.