Reasons, Procedure and Preparation For a Hydrogen Breath Test

Submitted on March 27, 2012

Hydrogen breath test is done to check two conditions.

In the first condition, a person may not be able to digest all the dietary sugars in the usual manner. Lactose is the most common sugar that isn't digested properly. People who are lactose intolerant may need to get this test done to check if they can digest other sugars like fructose and sucrose.

Reasons Why a Hydrogen Breath Test is Conducted

Hydrogen breath test is also done to check for bacterial overgrowth in the small intestine. This is a health problem in which, more than normal amount of colonic bacteria is there in the small bowel.

Both these health problems can cause distension, abdominal bloating, abdominal pain, diarrhea and flatulence.

Doctors often order the hydrogen breath test to check small intestinal bacterial overgrowth or SIBO. Studies have shown that several patients who had symptoms like diarrhea, bloating, and abdominal pain had this health disorder. Bacteria from the large intestine move into the small intestine and cause the disorder. There might be a connection between IBS and SIBO. Accurate diagnosis is very important in deciding the treatment plan and treating people accordingly.

More about lactose intolerance and hydrogen breath test: This test is used to determine if a person has abnormal bacteria in their colon or if they suffer from lactose intolerance.

Lactose intolerance is a condition in which a person cannot digest lactose, which is a sugar in milk. When that happens, a person may get gas, bloating, cramping and diarrhea after consuming any dairy products. If the lactase enzyme is absent or present in a very small quantity in a person's body, then it causes lactose intolerance.


This test can last for about two hours. You will be given a beverage with lactose and this may cause symptoms like flatulence, bloating, cramping or diarrhea. About fifteen minutes after consuming the drink, you will be asked to blow up a bag like a balloon. You will be asked to repeat this every fifteen minutes for the next two hours.

The air in the bags are then tested for hydrogen. Hydrogen is generally produced when there is undigested lactose in the intestine. An increase in the hydrogen levels means that the lactose in the beverage hasn't been digested properly.


Before you go in for the test, do tell the doctor if you have had a colonoscopy recently. The hydrogen test can be done only after a few weeks of the colonoscopy. You must inform the doctor if you are pregnant, allergic to certain medicines, have any diseases, or have a heart or lung condition.

You will be asked to stop taking antibiotics for a couple of weeks before the test; not eat or drink for about 8 hours before the test; and not chew bubblegum just before the test is conducted.