Frequent heartburn, defined as two or more episodes per week, is most often caused by repeated relaxation of the muscular valve between your esophagus and stomach, allowing acid to wash upward. This valve, called the lower esophageal sphincter, can weaken or relax too often for a range of reasons: excess weight, certain foods, medications, pregnancy, or a structural problem like a hiatal hernia. When heartburn hits this twice-a-week threshold, it typically qualifies as gastroesophageal reflux disease (GERD).
How the Valve Between Your Stomach and Esophagus Fails
At the bottom of your esophagus sits a ring of muscle that opens when you swallow and closes to keep stomach acid where it belongs. In people with frequent heartburn, this valve relaxes at the wrong times, without a swallow triggering it. These spontaneous relaxations are the single most common cause of acid reflux in both occasional and chronic sufferers.
The typical trigger is stomach distension. When you eat a meal, your stomach stretches, activating nerve sensors in the upper stomach. Those sensors send a signal up the vagus nerve to the brainstem, which then sends a signal back down telling the valve to relax. The bigger or faster the meal, the more the stomach stretches, and the more frequently these relaxation episodes occur. This is why heartburn so often strikes after eating.
Excess Weight and Abdominal Pressure
Carrying extra weight, especially around the midsection, is one of the strongest risk factors for frequent heartburn. Visceral fat (the fat packed around your organs, not the fat under your skin) increases the pressure inside your abdomen. That pressure pushes upward against your stomach, making it easier for acid to be forced through the valve and into your esophagus.
But the problem isn’t just about pushing acid upward. Abdominal pressure also impairs your esophagus’s ability to clear acid once reflux happens. Normally, a wave of muscular contraction sweeps refluxed acid back down within about 23 seconds. Research on external abdominal compression found that this clearance time more than tripled, to around 81 seconds, because acid kept splashing back up after each clearing wave. The longer acid sits in your esophagus, the more damage and burning you feel. Obesity also increases the frequency of spontaneous valve relaxations themselves, compounding the problem.
Tight clothing and belts that compress the abdomen can produce a similar, if milder, effect.
Hiatal Hernia
A hiatal hernia occurs when the upper part of your stomach pushes up through the diaphragm, the sheet of muscle that separates your chest from your abdomen. This matters because the diaphragm normally reinforces the esophageal valve, helping it stay shut. When the junction between your esophagus and stomach slides above the diaphragm, those supporting muscles can no longer tighten effectively. The hernia also traps a small pocket of acid above the diaphragm that can’t drain back into the stomach.
Hiatal hernias are extremely common. They affect roughly 20% of the general population, 50% of people over 50, and up to 70% of people over 70. Many cause no symptoms at all, but in people who already have a weak valve, a hiatal hernia significantly worsens reflux by adding low baseline valve pressure and straining as additional reflux mechanisms on top of the spontaneous relaxations.
Foods and Drinks That Relax the Valve
Certain foods don’t just irritate an already-inflamed esophagus. They physically weaken the valve, making reflux more likely to occur in the first place.
- Chocolate contains a compound called methylxanthine (chemically similar to caffeine) that directly relaxes the esophageal valve.
- Coffee, both regular and decaf, relaxes the valve. Caffeine plays a role, but other compounds in coffee contribute too, which is why switching to decaf doesn’t always help.
- Peppermint, garlic, and onions also relax the valve, which is why peppermint tea, often recommended for stomach upset, can actually worsen heartburn.
High-fat meals slow stomach emptying and increase distension, which triggers more spontaneous valve relaxations. Large meals do the same simply through volume. Acidic foods like tomatoes and citrus don’t necessarily cause more reflux events, but they make the acid that does reflux more irritating to the esophageal lining.
Medications That Cause or Worsen Heartburn
A surprisingly long list of common medications can trigger frequent heartburn through two different mechanisms. Some relax the esophageal valve, increasing the number of reflux events. Others directly irritate the esophageal lining, producing heartburn-like pain even without increased acid reflux.
Medications that relax the valve and increase reflux include calcium channel blockers and nitrates (used for blood pressure and heart disease), certain antidepressants, opioid painkillers, sedatives like benzodiazepines, medications for overactive bladder, and progesterone-based hormones. Theophylline, used for asthma and lung conditions, also weakens the valve.
Medications that directly irritate the esophagus include certain antibiotics, oral bone-density drugs, iron supplements, and potassium supplements. These pills can cause burning pain that mimics acid reflux if they dissolve against the esophageal wall, which is why many of them come with instructions to take them with a full glass of water and remain upright afterward.
If your heartburn started or worsened after beginning a new medication, that connection is worth exploring with whoever prescribed it. Often there are alternatives or timing adjustments that reduce the problem.
Pregnancy and Hormonal Changes
Up to two-thirds of pregnant women experience heartburn, and the primary driver is hormonal rather than mechanical. Rising progesterone levels during pregnancy reduce the resting pressure of the esophageal valve, making it easier for acid to escape upward. This effect begins early in pregnancy, often before the uterus is large enough to create meaningful abdominal pressure, which is why heartburn can start in the first trimester.
As pregnancy progresses, the growing uterus does add physical compression that worsens the situation. But the hormonal effect alone is enough to cause frequent reflux, and it typically resolves after delivery as progesterone levels drop.
Slow Stomach Emptying
When your stomach takes too long to move food into the small intestine, it stays distended longer, which means more spontaneous valve relaxations and more opportunities for reflux. This is a condition called gastroparesis, and heartburn is one of its hallmark symptoms alongside nausea, bloating, and feeling full quickly.
Gastroparesis happens when the vagus nerve, which controls stomach muscle contractions, is damaged or stops working properly. Diabetes is the most common cause, but it can also follow surgery, viral infections, or occur without an identifiable trigger. If your frequent heartburn comes with persistent nausea, vomiting, or feeling uncomfortably full after small meals, slow stomach emptying may be a contributing factor.
When Frequent Heartburn Signals Something More
Frequent heartburn on its own is common and manageable, but certain accompanying symptoms change the picture. Difficulty swallowing, pain when swallowing, unintentional weight loss, vomiting blood, or black stools are all considered alarm symptoms that warrant prompt investigation, typically with an endoscopy to look for esophageal damage.
Even without alarm symptoms, heartburn that persists despite over-the-counter acid-reducing medication, or that requires those medications more than twice a week, is a signal that the underlying cause needs to be identified rather than just managed symptomatically. Chronic, untreated acid exposure can lead to narrowing of the esophagus, erosion of the lining, or precancerous cellular changes that are best caught early.