A breath test is a noninvasive method of measuring the levels of certain gases in your breath to determine the presence of various digestive disorders.

Some people have difficulty digesting certain sugars such as fructose (fructose intolerance) and lactose (lactose intolerance). These undigested sugars move to the colon, where they get digested by bacteria and release hydrogen or methane gas. Small intestine bacterial overgrowth syndrome (SIBO) is another digestive condition characterized by the uncontrolled growth of bacteria in the small intestine, which digest food and release gas. These digestive conditions are characterized by bloating, gas, cramping or diarrhea.

A breath test measures the levels of gases that these bacteria produce, which can be detected in your breath. It is usually performed after fasting. You are instructed to breathe into a breath-analyzing machine before and at regular intervals after consuming a specific solution depending on what is being tested. The machine measures the level of hydrogen produced by the bacteria and helps determine the diagnosis of the digestive disorder.

What does a hydrogen breath test diagnose?

SIBO

If you’re diagnosed with SIBO, or small intestinal bacterial overgrowth, it means that bacteria from other parts of your gut have started to collect in the small intestine—and they shouldn’t be there.

Symptoms usually include:

• Cramping
• Diarrhea
• Abdominal bloating or distention
• Nausea
• Abdominal fullness or discomfort
• Foul-smelling gas

The treatment for SIBO is a round of antibiotics.  Even with treatment, though, SIBO can come back, especially in patients with autoimmune diseases—they may get SIBO as much as once a month.