GERD develops when the valve between your esophagus and stomach stops closing properly, allowing acid to wash back up repeatedly. This isn’t a single event but a combination of factors, some you can control and some you can’t, that weaken that valve over time. Roughly 1 in 10 people worldwide have it, so if you’re dealing with heartburn twice a week or more, you’ve crossed from occasional discomfort into GERD territory.
The Valve That Stopped Working
At the bottom of your esophagus sits a ring of muscle called the lower esophageal sphincter. It opens to let food into your stomach, then squeezes shut to keep acid where it belongs. In GERD, this valve malfunctions in one of three ways: it relaxes at random moments when it shouldn’t, it stays weak and partially open, or the junction where the esophagus meets the stomach shifts out of alignment (often due to a hiatal hernia).
The most common of these is called transient relaxation, where the valve briefly opens for no useful reason, letting a burst of acid splash upward. Everyone experiences this occasionally, but in people with GERD it happens far more often. After you eat, your stomach produces a layer of fresh acid that pools right at the top of your stomach contents, sitting closest to that valve. This “acid pocket” is why reflux tends to be worst after meals.
Once acid reaches the esophagus, your body normally clears it back down through swallowing and the natural wave-like contractions of the esophageal muscles. In some people, this clearing process is sluggish. The longer acid sits against the esophageal lining, the more damage it does, and the more likely you are to develop inflammation and pain that become chronic.
Weight, Diet, and Eating Habits
Carrying extra weight, particularly around your midsection, puts constant upward pressure on your stomach. That pressure pushes against the valve and makes it easier for acid to escape. Even modest weight gain can shift someone from occasional heartburn into frequent reflux, and losing weight is one of the most effective ways to reduce symptoms.
Certain foods and drinks don’t cause GERD on their own, but they relax the valve or increase acid production in ways that make existing reflux worse. Coffee, alcohol, chocolate, peppermint, fatty foods, and acidic foods like tomatoes and citrus are the usual triggers. Eating large meals has a bigger effect than most people realize, because a full, distended stomach increases pressure against the valve and enlarges that acid pocket sitting at the top. Eating late at night compounds the problem: lying down removes gravity’s help in keeping acid in your stomach, so food you ate right before bed is more likely to reflux.
Medications That Trigger Reflux
Some medications you take for completely unrelated conditions can weaken the esophageal valve or directly irritate the esophageal lining. If your GERD started or worsened around the time you began a new prescription, this is worth investigating with your doctor.
Medications that relax the valve and increase reflux include:
- Blood pressure and heart medications: calcium channel blockers, nitrates, and ACE inhibitors
- Certain antidepressants: particularly older tricyclic types
- Opioid pain medications
- Sedatives and anti-anxiety medications: including benzodiazepines
- Overactive bladder medications
- Asthma medications: specifically theophylline
A separate group of medications doesn’t affect the valve but directly irritates the esophageal lining, creating heartburn-like pain. Common painkillers like ibuprofen and aspirin fall into this category, along with certain antibiotics, iron supplements, and osteoporosis medications taken by mouth. The irritation from these drugs can mimic GERD or make existing GERD significantly worse.
Hiatal Hernia
A hiatal hernia occurs when the upper part of your stomach pushes up through the opening in your diaphragm where the esophagus passes through. This disrupts the normal anatomy of the junction between the esophagus and stomach, essentially pulling the valve out of position so it can’t seal properly. Not everyone with a hiatal hernia develops GERD, and not everyone with GERD has a hiatal hernia, but the two conditions overlap frequently. Hiatal hernias become more common with age, which partly explains why GERD tends to worsen as people get older.
Pregnancy and Hormonal Changes
If your GERD appeared during pregnancy, the cause is straightforward. Progesterone, which rises dramatically during pregnancy, relaxes smooth muscle throughout the body, including the esophageal valve. It also slows digestion, keeping food in the stomach longer than usual and giving acid more opportunity to reflux. As the pregnancy progresses, the growing uterus pushes upward on the stomach, adding physical pressure to the hormonal effects. The combination means food doesn’t move through the digestive tract as quickly, and the weakened valve can’t keep up. For most women, reflux improves significantly after delivery once hormone levels normalize and the physical pressure resolves.
Smoking and Alcohol
Smoking weakens the esophageal valve directly. Nicotine relaxes the sphincter muscle, and the repeated swallowing of air during smoking can increase the frequency of those inappropriate valve relaxations. Smoking also reduces saliva production, and saliva is one of the body’s natural tools for neutralizing acid in the esophagus and washing it back down. Alcohol has a similar dual effect: it relaxes the valve while also stimulating acid production in the stomach.
Stress and Sleep
Stress doesn’t produce extra stomach acid the way people once assumed, but it does appear to make the esophagus more sensitive to the acid that’s already there. People under chronic stress report more severe GERD symptoms even when objective measurements of acid exposure don’t change. Poor sleep creates a feedback loop: reflux disrupts sleep, and sleep deprivation increases pain sensitivity, which makes the same amount of reflux feel worse.
Why It Becomes Chronic
GERD often starts as occasional heartburn and gradually becomes more frequent. This progression happens because acid exposure itself damages the esophageal lining, and inflamed tissue is less effective at clearing acid and more sensitive to it. The longer acid sits against damaged tissue, the more the damage spreads, creating a cycle where the condition reinforces itself. This is why the American College of Gastroenterology uses a threshold of two or more episodes per week as the point where reflux shifts from a nuisance to a condition that needs active management. People who have frequent heartburn at that level also face a meaningfully higher risk of developing changes to the esophageal cells over time, which makes controlling the reflux more important the longer it persists.
For most people, GERD results from several of these factors layering on top of each other rather than a single cause. You might have a mildly weak valve that was never a problem until weight gain added abdominal pressure, or a hiatal hernia that only became symptomatic after starting a medication that relaxes the sphincter further. Understanding which factors apply to you is the first step toward figuring out which ones you can change.