Merck Manual

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Some Causes and Features of Gas-Related Complaints

Some Causes and Features of Gas-Related Complaints


Common Features*



Air swallowing

People with or without awareness of swallowing air

Sometimes in people who smoke or chew gum excessively

Sometimes in people who have esophageal reflux or ill-fitting dentures

A doctor’s examination alone

Gas from carbonated beverages

Beverage consumption usually obvious based on person’s history

A doctor’s examination alone

Distention or bloating

Air swallowing

See Belching, above

A doctor’s examination alone

Abdominal pain related to defecation, associated with a change in the frequency or consistency of stool, or both

No warning signs

Typically begins during adolescence and the 20s

A doctor’s examination

Examination of stool

Blood tests

Poor emptying of the stomach (gastroparesis), usually due to other disorders such as diabetes, connective tissue disorders, or neurologic disorders

Nausea, abdominal pain, and sometimes vomiting

Early fullness (satiety)

Sometimes in people known to have a disorder that causes it

Sometimes in people taking drugs with anticholinergic effects

Upper endoscopy§ and/or nuclear scanning that evaluates stomach emptying

If a drug cause is suspected, stopping the drug to see whether symptoms go away

Long-standing symptoms, particularly in young women

In people who are thin but still very concerned about excess body weight

A doctor’s examination alone

A long history of hard, infrequent bowel movements

A doctor’s examination

Pressure measurements of the anus and rectum (anorectal manometry)

New, persistent bloating in middle-aged or older people

For colon cancer, sometimes blood in stool (blood may be visible or detected during a doctor's examination)

If ovarian cancer is suspected, ultrasonography of the pelvis

Passing of gas (flatulence)

Foods, including beans, dairy products, vegetables (such as onions, celery, carrots, or Brussels sprouts), fruits (such as raisins, bananas, apricots, and dates or apple, pear, or prune juice), and foods containing fructose (such as cola sodas, honey, or nuts), prunes, or waffle or maple syrup, or complex carbohydrates (such as pretzels, bagels, or wheat germ)

Symptoms that develop mainly when food that can cause gas is consumed

A doctor’s examination

Elimination of the suspected food from diet to see whether symptoms go away

Bloating, cramps, and diarrhea after consuming milk products

A breath test to detect hydrogen, indicating undigested food

Light-colored, soft, bulky, and unusually foul-smelling stools that may appear oily

Weakness, loss of appetite, and diarrhea

Often begins in childhood

Blood tests to measure antibodies produced when people with celiac disease eat foods containing gluten and biopsy of the upper small intestine

Light-colored, soft, bulky, and unusually foul-smelling stools that may appear oily

Nausea, loss of appetite, diarrhea, abdominal cramps, and weight loss

Blood tests and biopsy of the small intestine

* Features include symptoms and the results of the doctor's examination. Features mentioned are typical but not always present.

† Although a doctor's examination is always done, it is mentioned in this column only if the diagnosis can sometimes be made by the doctor's examination alone, without any testing.

‡ Doctors usually do a urine pregnancy test for all girls and women of childbearing age.

§ Upper endoscopy is examination of the esophagus, stomach, and the first segment of the small intestine (duodenum) using a flexible viewing tube called an endoscope.