Breath testing

What breath tests are offered in the Allergy Clinic?

We offer two types of breath tests. We can test for lactose intolerance and small intestinal bacterial overgrowth (SIBO).

Lactose intolerance (which is different to a true allergy) is when the body can not properly digest lactose, a sugar found in dairy products. Symptoms include tummy pains, sickness, bloating and diarrhoea after eating lactose-containing foods.

SIBO is the presence of excessive bacteria in the small bowel. This condition can also cause similar gut symptoms.

What do the tests involve?

You will be given a sugar solution to drink. Then you will be asked to blow into a special tube every 15 - 30 minutes to collect a series of breath samples. The SIBO test takes just over an hour to complete and the lactose test will take about 2 hours to complete. Bring something to read to occupy yourself between the breath samples!

Is there anything I need to do before the test?

It is recommended to not have taken antibiotics for 4 weeks prior to the test. We recommend not taking any laxatives, constipating-agents or anti-sickness medications for 1 week before the test. The day before the test there are strict dietary instructions which your doctor will advise you further about. You must then fast from 8pm the night before the test (water is allowed). On the day of the test, continue to fast, do not smoke and do not exercise within one hour of the test.

What are the side-effects of this test?

Some people will experience needing to use the toilet to open their bowels during the test or will get side effects like bloating and tummy discomfort. Other people will get no symptoms at all.

What happens after the test?

The results are available straight away for your doctor to interpret. Your doctor can discuss with you the next steps if lactose intolerance is proven, which may involve avoiding all dairy-containing foods. Likewise, your doctor can discuss SIBO with you if this diagnosis is proven, which could also involve dietary changes or your doctor may recommend medication such as antibiotics. If the tests are negative, then your doctor can suggest next steps to explore other diagnoses.