What causes heartburn?

To know why heartburn happens, it can help to understand how your esophagus and stomach work. When you eat, the food passes down a long tube that connects your mouth and stomach. This tube is called the esophagus. At the bottom of the esophagus is a valve, called the esophageal sphincter. This valve opens to let food through and then closes to keep your stomach contents down. Inside your stomach is a very strong acidic mixture that starts the process of breaking down your food (digestion). Your stomach is designed to hold this mixture. However, your esophagus isn’t able to hold this mixture without getting hurt.

Sometimes, the valve that separates your stomach and esophagus doesn’t close properly, and some of the acidic mixture from your stomach goes back up the esophagus. This is called reflux. When you have reflux, you’ll often feel the burning sensation that’s heartburn. There are a few medical conditions that can cause reflux and make you feel heartburn, including:

  • Pregnancy.
  • Hiatal hernia (when the stomach bulges up into the chest).
  • Gastroesophageal reflux disease (GERD).
  • Certain medications, especially anti-inflammatory drugs and aspirin.

There are also diet and lifestyle habits that can cause heartburn, including:

  • Eating habits: If you eat large portions of food or eat to close to bedtime, you may be more likely to experience heartburn. The types of food you eat can also cause heartburn. Foods like onions, citrus fruits, high-fat foods, and tomatoes or tomato-based products can all play a part in heartburn. Drinks can also cause heartburn. These can include alcohol, citrus juices, caffeinated beverages and carbonated beverages.
  • Lifestyle habits: There are certain lifestyle habits that can increase your risk of having heartburn, including being overweight or being a smoker. These things are closely linked to the conditions that cause this symptom (GERD and hiatal hernia, for example). Your chances of having heartburn could also go up as your stress level increases. Even tight clothes and belts can be a cause of heartburn.

Last reviewed by a Cleveland Clinic medical professional on 01/22/2020.


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