Heartburn is a burning sensation in your chest caused by stomach acid flowing backward into the esophagus, the tube that connects your mouth to your stomach. It has nothing to do with your heart, despite the name. Most people experience it occasionally after a heavy meal, but when it happens twice a week or more, it crosses into a chronic condition called gastroesophageal reflux disease (GERD).
How Heartburn Happens
A muscular ring called the lower esophageal sphincter sits at the junction between your esophagus and stomach. It works like a one-way valve: it opens to let food drop into the stomach, then tightens to keep everything from coming back up. When this valve weakens or relaxes at the wrong time, acidic stomach contents wash upward into the esophagus, which lacks the protective lining the stomach has. That acid contact produces the characteristic burning feeling behind your breastbone, often accompanied by a sour or bitter taste in the back of your throat.
The sphincter is controlled by a mix of nerves and hormones, which means a surprisingly wide range of things can interfere with it. Foods, medications, emotions like anxiety or anger, and even your body position all influence how well it seals.
Foods and Drinks That Trigger It
The most common dietary triggers share two traits: they either relax the sphincter or slow digestion, letting food sit in the stomach longer and increasing the chance of reflux. High-fat, high-salt, and spicy foods top the list. Fried food, fast food, pizza, fatty meats like bacon and sausage, cheese, and processed snacks like potato chips are frequent offenders. Spices such as chili powder, black pepper, white pepper, and cayenne can also set it off.
Several other foods cause problems through slightly different mechanisms. Caffeine in coffee, tea, cocoa, and cola both loosens the sphincter and stimulates extra acid production, a double hit. Chocolate and peppermint relax the sphincter directly. Tomato-based sauces and citrus fruits are highly acidic on their own, irritating an already-sensitive esophagus. Carbonated beverages introduce gas that distends the stomach and pushes contents upward.
Body Weight and Abdominal Pressure
Carrying extra weight, particularly around your midsection, is one of the strongest risk factors for chronic heartburn. The reason is mechanical: abdominal fat increases the pressure inside your abdomen, and that pressure pushes against the stomach and the sphincter above it. Research published in Gastroenterology found that waist circumference correlates directly with intra-abdominal pressure, and that this pressure can overcome even a normally functioning sphincter. Notably, waist size was a better predictor than overall body mass index, which means where you carry weight matters more than how much you weigh overall.
This same pressure dynamic explains why tight belts, shapewear, and snug waistbands can worsen symptoms. Anything that squeezes the abdomen pushes stomach contents toward the esophagus.
How Sleep Position Plays a Role
Heartburn often worsens at night because lying flat removes gravity from the equation. When you’re upright, gravity helps keep stomach acid where it belongs. Lie down, and acid can flow freely toward the esophagus, especially if you’ve eaten within the last two hours.
Your sleeping side matters, too. The American Gastroenterological Association recommends sleeping on your left side, because of the way the stomach and esophagus are arranged anatomically. In this position, the stomach sits below the esophageal opening, and gravity pulls acid away from the sphincter. Sleeping on your right side does the opposite, promoting acid flow into the esophagus and increasing reflux episodes. Elevating your head and upper body by about six inches, using a wedge pillow or bed risers, also reduces nighttime symptoms significantly.
Hiatal Hernia
A hiatal hernia occurs when the upper part of the stomach pushes through a small opening in the diaphragm (called the hiatus) and bulges into the chest cavity. The diaphragm normally reinforces the sphincter by adding external pressure around it. When part of the stomach slides above the diaphragm, that reinforcement disappears, and acid can back up into the esophagus much more easily. Small hiatal hernias often cause no symptoms at all, but larger ones are a common cause of persistent, hard-to-manage heartburn.
Pregnancy and Hormonal Changes
Heartburn is extremely common during pregnancy, and two separate mechanisms are responsible. First, rising levels of progesterone relax the esophageal sphincter and slow digestion, which keeps food in the stomach longer and gives acid more opportunity to reflux. Second, as the uterus grows, it pushes upward against the stomach, physically compressing it. The combination of a relaxed sphincter and increased abdominal pressure makes heartburn nearly unavoidable for many pregnant women, especially in the third trimester.
Medications That Contribute
Several common medication classes can relax the sphincter as a side effect. These include certain blood pressure drugs (calcium channel blockers), anti-anxiety medications (benzodiazepines), some asthma inhalers (beta agonists), heart medications (nitrates), and certain antidepressants and bronchodilators. Smoking has the same effect, loosening the sphincter and increasing acid exposure. If you take any of these and experience frequent heartburn, it’s worth discussing the connection with whoever prescribed them.
Heartburn vs. Heart Attack
Heartburn and heart attacks can feel remarkably similar. Even experienced doctors sometimes can’t distinguish them based on symptoms alone, which is why emergency rooms run heart tests immediately when someone arrives with chest pain.
Heartburn typically produces a burning sensation in the chest and upper abdomen that starts after eating or when lying down, responds to antacids, and may come with a sour taste or a small amount of fluid rising into the throat. A heart attack more often feels like pressure, tightness, or squeezing in the chest or arms that spreads to the neck, jaw, or back. It may also involve shortness of breath, cold sweat, sudden dizziness, or unusual fatigue. The critical difference: heartburn pain doesn’t usually come with those whole-body symptoms.
If you have persistent chest pain and aren’t sure whether it’s heartburn, treat it as an emergency. Both heartburn and early heart attacks can produce pain that comes and goes or fades on its own, so the fact that symptoms subside doesn’t mean they weren’t serious.
When Occasional Becomes Chronic
Everyone gets heartburn now and then. It becomes a medical concern when it happens twice a week or more, or when you find yourself relying on over-the-counter antacids that often. At that frequency, stomach acid is spending enough time in contact with the esophagus to potentially damage its lining, a condition that can progress over months or years if left unmanaged. The shift from occasional heartburn to GERD isn’t always dramatic. It often creeps up gradually as triggers accumulate: a few extra pounds, a new medication, larger portions at dinner, eating closer to bedtime.