Heartburn happens when stomach acid flows backward into your esophagus, the tube that connects your mouth to your stomach. A ring of muscle at the bottom of your esophagus, called the lower esophageal sphincter, normally stays closed to keep acid where it belongs. When that muscle relaxes at the wrong time or doesn’t seal tightly enough, acid escapes upward and irritates the esophageal lining, producing that familiar burning sensation behind your breastbone.
The reasons this happens range from what you ate an hour ago to structural changes in your body you might not know about. Understanding your specific triggers is the first step toward fewer episodes.
Foods and Drinks That Trigger Reflux
Certain foods relax the lower esophageal sphincter, increase acid production, or both. The most common culprits fall into a few categories:
- Fatty and fried foods take longer to digest, which means your stomach stays full longer and acid is more likely to push back up.
- Spicy foods, citrus, tomato sauces, and vinegar can intensify the burning by directly irritating the esophageal lining.
- Chocolate, caffeine, peppermint, and alcohol relax the sphincter muscle, making it easier for acid to escape.
- Carbonated drinks and onions are also well-documented triggers.
Not everyone reacts to the same foods. You might tolerate coffee just fine but get hit hard by tomato sauce. Paying attention to which foods consistently precede your symptoms is more useful than avoiding everything on a generic list.
How Body Weight and Smoking Play a Role
Carrying extra weight, especially around your midsection, puts physical pressure on your stomach. That pressure pushes acid upward toward your esophagus, even when your sphincter is functioning normally. This is one reason heartburn tends to get worse as people gain weight and often improves when they lose it.
Smoking weakens the lower esophageal sphincter over time and increases acid production. If you smoke and experience frequent heartburn, quitting can noticeably reduce your symptoms.
Timing, Posture, and Nighttime Symptoms
Gravity helps keep acid in your stomach when you’re upright. The moment you lie down or bend over, that advantage disappears. Acid can pool against the sphincter and slip through more easily, which is why heartburn often strikes at night or after a nap.
Eating a large meal and then lying down within a couple of hours is one of the most reliable ways to trigger an episode. Giving your stomach time to empty before you recline makes a real difference. Elevating the head of your bed by a few inches (not just adding pillows, which can bend your body in a way that increases abdominal pressure) also helps keep acid where it belongs overnight.
Medications That Make Heartburn Worse
Several common medications can trigger or worsen reflux, and many people don’t realize the connection. Some drugs irritate the esophageal lining directly. These include common pain relievers like ibuprofen and aspirin, certain antibiotics, iron supplements, and osteoporosis medications taken by mouth.
Other medications relax the lower esophageal sphincter, making reflux more likely. Blood pressure drugs (particularly calcium channel blockers), certain antidepressants, sedatives, opioid painkillers, and medications for overactive bladder all fall into this category. If your heartburn started or worsened around the time you began a new medication, that connection is worth exploring with your prescriber.
Pregnancy and Hormonal Changes
Heartburn affects a large proportion of pregnant people, and it has two distinct causes that compound each other. Early in pregnancy, rising progesterone levels relax the lower esophageal sphincter, allowing acid to escape more easily. Progesterone is essential for maintaining a healthy pregnancy, so this side effect is difficult to avoid.
Later, especially in the third trimester, the growing uterus crowds the stomach and pushes it upward. This physical compression forces acid into the esophagus even when the sphincter is working reasonably well. The combination of hormonal relaxation and physical pressure explains why heartburn tends to get progressively worse as pregnancy advances, then resolves after delivery.
Hiatal Hernia: A Hidden Structural Cause
Your esophagus passes through a small opening in your diaphragm before connecting to your stomach. In a hiatal hernia, part of the stomach pushes up through that opening into the chest cavity. Small hiatal hernias often cause no symptoms at all, but larger ones allow food and acid to back up into the esophagus more easily.
Hiatal hernias are common, especially in people over 50, and many people have one without knowing it. If your heartburn is frequent and doesn’t respond well to dietary changes, a hiatal hernia could be a contributing factor your doctor can identify with imaging.
When Heartburn Feels Like Something More Serious
Heartburn and heart attacks can feel surprisingly similar. Even experienced doctors sometimes can’t tell the difference based on symptoms alone. Typical heartburn produces a burning sensation in the chest that usually occurs after eating, responds to antacids, and may come with a sour taste or a small amount of fluid rising into the back of your throat.
A “textbook” heart attack involves sudden, crushing chest pain and difficulty breathing, often during physical exertion. But many heart attacks don’t follow that pattern. The pain can be mild, come and go, and feel a lot like indigestion. If you have persistent chest pain and you’re not sure it’s heartburn, call 911. If you had an episode of unexplained chest pain that went away on its own, contact your doctor afterward. Both heartburn and developing heart attacks can produce symptoms that subside temporarily, so resolution of the pain alone doesn’t rule out a cardiac event.
What Happens if Reflux Continues Long-Term
Occasional heartburn is uncomfortable but not dangerous. Chronic, ongoing reflux is a different story. When stomach acid repeatedly washes over the lining of your lower esophagus, it can cause inflammation, ulcers, and scarring that narrows the esophagus over time.
In some people, long-standing reflux triggers a condition called Barrett’s esophagus, where the normal flat, pink cells lining the esophagus are replaced by thicker, different tissue. Barrett’s esophagus is associated with a slightly increased risk of esophageal cancer, though most people with the condition never develop cancer. The risk is small enough that it’s managed through regular monitoring rather than aggressive intervention, but it’s one more reason frequent heartburn is worth addressing rather than just tolerating week after week.