Risk factors

Conditions that cause difficulty with digestion can increase the risk of heartburn. These include:

• Obesity
• Excess weight puts extra pressure on your stomach and diaphragm — the large muscle that separates your chest and abdomen — forcing open the lower esophageal sphincter and allowing stomach acids to back up into your esophagus. Eating very large meals or meals high in fat may cause similar effects.
• Hiatal hernia
  
• If this protrusion of part of your stomach into your lower chest is large, it can worsen heartburn by further weakening the lower esophageal sphincter muscle.
• Pregnancy
  
• Pregnancy results in greater pressure on the stomach and a higher production of the hormone progesterone. This hormone relaxes many of your muscles, including the lower esophageal sphincter.
• Asthma
  
• Doctors aren't certain of the exact relationship between asthma and heartburn. It may be that coughing and difficulty exhaling lead to pressure changes in your chest and abdomen, triggering regurgitation of stomach acid into your esophagus. Some asthma medications that widen (dilate) airways may also relax the lower esophageal sphincter and allow reflux. Or it's possible that the acid reflux that causes heartburn may worsen asthma symptoms. For example, you may inhale small amounts of the digestive juices from your esophagus and pharynx, damaging lung airways.
• Diabetes
  
• One of the many complications of diabetes is gastroparesis, a disorder in which your stomach takes too long to empty. If left in your stomach too long, stomach contents can regurgitate into your esophagus and cause heartburn.
• Gastric outlet obstruction
  
• This is a partial blockage caused by scarring, an ulcer or a growth near the valve (pylorus) in the stomach that controls the flow of food into the small intestine. It can keep this valve from working properly or can obstruct the release of food from the stomach. Food doesn't empty from your stomach as fast as it should, causing stomach acid to build up and back up into your esophagus. This usually causes more signs and symptoms than just heartburn, such as abdominal pain, difficulty eating, weight loss, nausea and vomiting. If you experience any of these signs and symptoms, consult your doctor.
• Delayed stomach emptying
  
• In addition to diabetes or an ulcer, abnormal nerve or muscle functions can delay emptying of your stomach, causing acid backup into the esophagus. Medications may also lead to delayed stomach emptying. These include narcotics, some antidepressants and antihistamines.
• Connective tissue disorders. Diseases such as scleroderma that cause muscular tissue to thicken and swell can keep digestive muscles from relaxing and contracting as they should, allowing acid reflux.
• Zollinger-Ellison syndrome. One of the complications of this rare disorder is that your stomach produces extremely high amounts of acid, increasing the risk of acid reflux.