He had years of pain, bloating, and constipation

For 10 years, the patient had been complaining of pain just under his ribs on the left side. He was bloated and constipated and had a dry mouth.

He tried treating his symptoms on his own, taking laxatives and going for walks, which gave him minimal, temporary relief.

At first, his doctors thought he might be suffering from splenic flexure syndrome, in which gas gets trapped in one of the curves of the intestines.

They gave him charcoal pills and simethicone, which reduced the gas for a short while before the discomfort grew worse.

A CT scan of the patient's belly showed no signs of any abnormality. Gastroenterologists searched his colon, esophagus, stomach, and duodenum with colonoscopies and endoscopies, looking for cancer, obstruction, inflammation.

They found nothing.

The patient was tested for gluten sensitivity. Those results came back negative.

He was referred to a motility expert, who did tests to see if the muscles in his esophagus and small intestine were contracting properly.

Those studies, at last, revealed a problem. He was told he had gastroparesis, a condition in which autonomic muscle contractions in the GI tract are too weak to completely empty the stomach of its contents. He was given motility agents to jump-start the GI tract, but they brought little improvement.

His doctor speculated that the condition might have been caused by a bacterial overgrowth in the small bowel, occasionally seen in patients with gastroparesis. So he was given rifaximin, an antibiotic that just remains in the gut after taking it by mouth. It helped somewhat, but not much and not for long.

In addition to his gastric distress, the patient was having persistent problems with dry mouth. Without saliva to help control bacteria in his mouth, his teeth were deteriorating.

To supplement the medicines he was given, the patient tried a panoply of diets. Low residue. High residue (to reduce the amount of stools). Low fiber. High fiber. He made an effort to get more exercise.

Still, no improvement.

His doctors ran all the tests again. Again, no answers.

Depressed and beginning to believe that he might be doomed to bloated misery for the rest of his life, he went to see his internist for an annual checkup.

"Let's run through your medications one more time," the doctor said.

The patient listed all his prescriptions.

"Any over-the-counter meds, other than Metamucil?" the doctor asked.

"Oh yeah," he said. "I take Benadryl to sleep."

"How much?"

"Four pills a night."

"Four?"

"Four."

The doctor smiled. "That may be it," he said.

The patient said that in all the years he had been going to see doctors about his digestive problems, he had never mentioned taking Benadryl.

"No one asked," he explained.

His physician admitted that he wished he had posed the question years ago. He told the man that each pill contains a 25 mg dose of diphenhydramine. Usually, one dose of the antihistamine makes people groggy enough to get a good six or eight hours of sleep. It is unusual to need 50 mg. And 100 mg?

Unprecedented in the doctor's experience.

Diphenhydramine has anticholinergic effects, the doctor said: it shuts downs the nerves that trigger contractions in the intestines.

He told the patient to stop taking the drug for six weeks and see if he felt better. In the meantime, he prescribed another sedative to help treat his insomnia.

At his next appointment, a month and a half later, the patient reported that - for the first time in a decade - he was making regular, productive trips to the bathroom.

And his saliva?

Back in mouthwatering action, ready for anything he wanted to put on his plate - with or without gluten, fiber, and residue.