Q: My friend seems to choke at least three times a week while drinking or eating. I am worried he may not be able to dislodge the food one of these times. Is there a condition that could cause this or is he chewing improperly or swallowing incorrectly?

A: You are right to be concerned. Your friend almost certainly has a swallowing disorder. He needs to be diagnosed and treated.

There are many possible reasons for why food sticks in the esophagus. This passage connects the mouth and stomach. Doctors call this swallowing problem dysphagia.

One possible cause is a narrowed lower esophagus due to excessive acid reflux. Another is achalasia, in which food is poorly moved through the esophagus and has difficulty getting by an overly tight sphincter at the bottom of the esophagus. Esophageal cancer can also cause dysphagia.

Several other conditions are worth mentioning. Noncancerous growths that line the esophagus, called webs and rings, can narrow the esophagus and trap swallowed food. More recently, we learned that eosinophilic esophagitis can be a frequent cause of dysphagia. This disorder is associated with allergies.

Your friend's doctor will almost certainly send him for a barium swallow x-ray and an upper endoscopy to diagnose the problem. Esophageal manometry might also be used. This test measures the pressure within the esophagus and its lower sphincter.

You might tell your friend that the likelihood he has cancer is low, and the chance that he will find relief once he has been diagnosed is high.

Stephen Goldfinger, M.D., is a professor of medicine at Harvard Medical School. He is a graduate of Columbia College of Physicians and Surgeons, and his clinical base is at the Massachusetts General Hospital.