Gastroparesis is typically caused by damage to the vagus nerve. This nerve, which originates in the brainstem and is involved in sensory and motor functions, also controls the muscular contractions of the stomach. Damage to the stomach muscles can also cause gastroparesis, although this is less common.

There are a number of risk factors that can result in damage to the vagus nerve or stomach muscles. The most common is diabetes. Elevated blood sugar (glucose) levels experienced by patients with diabetes can result in damage to the vagus nerve.

Another common risk factor is surgery to the esophagus, stomach or duodenum (the first part of the small intestine connected to the stomach). Gastroparesis can develop immediately after any of these surgeries or years later. However, not every patient who experiences damage to the vagus nerve during surgery will develop gastroparesis.

Other common risk factors of gastroparesis include:

• Medications. Certain common medications can delay the emptying of stomach contents. These drugs include narcotic pain medications, tricyclic antidepressants (medications to treat depression), lithium (medication to treat mood disorders) and progesterone (a female hormone that is used in oral contraceptives [birth control pills] and hormone replacement therapy). When patients stop taking the medication, however, symptoms usually improve.
  
  
• Cancer treatments. Patients who receive chemotherapy or radiation therapy to the chest sometimes develop gastroparesis.
  
  
• Other disorders. There are a wide range of disorders that have been linked to gastroparesis, including eating disorders (e.g., anorexia nervosa, bulimia nervosa), smooth muscle disorders (e.g., scleroderma), nervous system diseases (e.g., Parkinson’s disease), cyclic vomiting syndrome, cirrhosis, kidney failure and metabolic disorders (e.g., high levels of thyroid hormones). Viral infections can also lead to gastroparesis in some people.

In some patients, the cause of gastroparesis is unknown (idiopathic).