Heartburn is a burning pain in your chest, just behind the breastbone, caused by stomach acid flowing backward into your esophagus. It affects 10 to 20% of adults in Western countries and is one of the most common digestive complaints. Despite the name, it has nothing to do with your heart.
What Happens Inside Your Body
At the bottom of your esophagus sits a ring of muscle that acts as a one-way valve between your throat and your stomach. Under normal conditions, this valve stays closed with enough force to keep stomach acid where it belongs. When you swallow, it relaxes for about 6 to 10 seconds to let food pass through, then tightens again.
Heartburn happens when this valve relaxes at the wrong time, outside of swallowing. These spontaneous relaxations last longer than normal ones, anywhere from 10 to 45 seconds, and they allow acidic stomach contents to wash up into the esophagus. Your stomach has a thick protective lining designed to handle acid. Your esophagus does not. When acid touches the esophageal lining, you feel that characteristic burn.
You might assume the valve is simply weak in people who get heartburn, but that’s not usually the case. In most people with mild to moderate reflux, the valve’s resting pressure is completely normal. The problem is the timing and frequency of those spontaneous relaxations, often triggered by the stomach stretching after a meal.
What Heartburn Feels Like
The hallmark symptom is a burning sensation that starts behind your breastbone and can spread upward into your throat. It typically shows up after eating, and it gets worse when you lie down or bend over. You may also notice a bitter or sour taste in your mouth, especially at night, or feel a small amount of stomach contents rising into the back of your throat.
Episodes can last anywhere from a few minutes to a couple of hours. Antacids usually bring relief quickly, which is one way to distinguish heartburn from something more serious.
Common Triggers
Certain foods and habits make heartburn more likely by either increasing stomach acid, relaxing the valve, or keeping food in your stomach longer than usual:
- Fatty and fried foods take longer to digest, which means your stomach stays full and pressurized for longer.
- Spicy foods, citrus, tomato sauces, and vinegar can intensify the burning sensation directly.
- Chocolate, caffeine, peppermint, onions, carbonated drinks, and alcohol all tend to worsen symptoms.
- Large meals increase pressure inside the stomach, which pushes acid upward.
- Lying down after eating removes gravity’s help in keeping acid down. Eating within three to four hours of bedtime is one of the most common triggers for nighttime symptoms.
- Vigorous exercise right after a meal can force acid into the esophagus.
Why It Gets Worse at Night
When you’re upright, gravity helps keep stomach acid in your stomach. Lying flat eliminates that advantage. But sleep position matters more than most people realize. When you sleep on your right side, your stomach ends up positioned above your esophagus, essentially pouring acid toward the valve. Your body also takes longer to clear the acid away in this position.
Sleeping on your left side flips this arrangement. The esophagus sits above the stomach, so acid is less likely to flow upward. A systematic review of multiple studies found that left-side sleeping significantly reduced both the total time acid spent in the esophagus and how long each reflux episode lasted, compared to right-side or back sleeping. If nighttime heartburn is a regular problem for you, switching to your left side is one of the simplest changes you can make.
Heartburn During Pregnancy
Heartburn is extremely common during pregnancy, and hormones are the main reason. Progesterone, which rises sharply throughout pregnancy, relaxes smooth muscle tissue throughout the body, including the valve at the base of the esophagus. With a looser valve, acid escapes more easily. The physical pressure of a growing uterus plays a smaller role than most people think, though it can contribute later in pregnancy.
When Heartburn Becomes GERD
Occasional heartburn after a heavy meal is normal. When it becomes frequent enough to feel bothersome or starts causing complications, it crosses into gastroesophageal reflux disease, or GERD. There’s no strict cutoff like “twice a week,” though that’s a commonly used guideline. The key distinction is whether the symptoms are troublesome to you and affecting your quality of life.
GERD that persists for years without adequate treatment can lead to changes in the esophageal lining. In a condition called Barrett’s esophagus, the normal flat cells lining the lower esophagus get replaced by thicker tissue that resembles the stomach lining. Barrett’s esophagus is associated with a slightly increased risk of esophageal cancer, though most people with the condition never develop cancer. People whose reflux doesn’t improve with medication are at higher risk for these changes, which is why persistent symptoms are worth addressing rather than ignoring.
How Heartburn Differs From a Heart Attack
The overlap in symptoms is real and worth understanding. Both can cause chest discomfort, and both can come and go. But the character of the pain is different. Heartburn produces a burning sensation that’s typically linked to eating, responds to antacids, and may come with a sour taste. A heart attack produces pressure, tightness, or squeezing in the chest or arms that can radiate to the neck, jaw, or back. It’s often accompanied by shortness of breath, cold sweat, lightheadedness, or sudden fatigue.
The important caution: the pain from both conditions doesn’t have to last a long time to be significant. If you’re experiencing chest pressure with shortness of breath or cold sweats, treat it as a cardiac emergency regardless of whether you think it might just be reflux.
Treatment Options
Over-the-counter medications for heartburn fall into three categories, each working differently and suited to different situations.
Antacids neutralize acid that’s already in your stomach. They work within minutes and are useful for occasional, predictable heartburn. Their relief is real but short-lived.
H2 blockers reduce the amount of acid your stomach produces. They take longer to kick in than antacids but provide relief for roughly four hours. They work well for people who get heartburn a few times a week and want something more sustained.
Proton pump inhibitors, or PPIs, are the strongest option. They shut down acid production more completely, maintaining lower acid levels for 15 to 22 hours per day. They’re designed for frequent heartburn or GERD, not occasional use. Timing matters with PPIs: they should be taken 30 to 60 minutes before a meal to work properly, since they have a short window of activity in your body.
Beyond medication, the lifestyle changes that make the biggest difference are eating smaller meals, not lying down for at least three hours after eating, sleeping on your left side, and identifying your personal trigger foods through simple elimination.