Lactulose Tolerance Test

What is Lactulose Intolerance?

Small Intestinal Bacterial Overgrowth Syndrome (SIBOS) is a condition where the small intestine is populated by an abnormal amount and/or types of bacteria.

SIBOS can be caused by many gastrointestinal conditions. It can be diagnosed by the lactulose breath test. In this test, a non-absorbable sugar solution is swallowed and hydrogen and methane gases are measured in the breath.  Gas levels rise as the sugar solution passes through the intestine resulting from fermentation of the sugar by bacteria. If the gas levels rise quickly and to an abnormal level a diagnosis of small intestinal bacterial overgrowth can be made and treated. The majority of the gas that is produced by bacteria in the small intestine and then most of it is eventually absorbed by the lining and then taken up in the blood stream and then is expelled through the lungs. The effects of SIBOS in people include a variety of symptoms including bloating, gas, pain, diarrhea, constipation, irritable bowel syndrome, muscle pain (fibromyalgia), interstitial cystitis, restless leg syndrome, rosacea, and bad breath.

The most common cause of SIBOS is the reduction of the normal cycle of muscular activity of the small intestine at night.  It is during these muscular contractions that the small intestine is stripped clean and by doing so keeping the bacterial population low.  This disorder can result from an insult caused by infection in the past (including traveler’s diarrhea, gastroenteritis, and food poisoning).  The effect can last for many years and as a result the normally small population of small intestinal bacteria will grow.

Treatment of SIBOS

To treat SIBOS, your doctor might recommend specific antibiotics.  After antibiotic treatment is finished and the symptoms improve, there is sometimes an underlying muscular disturbance therefore your doctor might also recommended some medication which stimulates small intestinal muscular activity as a long term treatment to prevent relapse of SIBOS.  Some individuals might suffer from damage to the lining of the small intestine by SIBOS, therefore it is important to try to help repair this intestinal permeability (also known as “leaky gut”).  Common treatments for this may include 1 month of Zinc 200 milligrams daily and a probiotic capsule (healthy bacteria). If there is a relapse of the infection with return of the original symptoms, then other antibiotics may need to be prescribed again.

During the anti-biotic treatment it is not unusual to have more gas, discomfort and diarrhea.  Some people find that their symptoms are improved by reducing their carbohydrate intake (bread, pasta, rice, cereal, dairy with lactose and fruit). People who have long standing of irritable bowel syndrome or fibromyalgia and are taking anti-depressants for these conditions may need to continue this therapy for a period of time. If SIBOS is effectively treated then these medications can be discontinued under your doctor’s direction.

Restriction of artificial sugars can be helpful for some people as a long-term way to reduce the risk of relapse of SIBOS. Other food intolerances such as Lactose intolerance may be a temporary or a long-term problem for people who have SIBOS.

Testing for SIBOS

The substance used to test for SIBOS is called Lactulose.  Lactulose is a synthetic disaccharide that cannot be absorbed by anyone and is always fermented producing hydrogen.  Lactulose is also used as baseline test before other intolerance tests are performed. 

Lactulose is given as a solution in water to drink and Hydrogen/Methane breath testing along with symptom monitoring is performed at regular intervals for 2-3 hours to determine the following;

  • Presence of SIBOS
  • Establish oro-cecal transit time
  • Establish non-hydrogen producers
  • Investigation of constipation


If you know that something is not quite right, then find out for your test today

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1300 263 257

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Do any of these products make you feel sick?

  • Jelly Beans
  • Bread
  • Pear
  • Muffin
  • Sports Drinks
  • Nicorette Gum
  • Honey
  • Pasta
  • Apple
  • Ice Cream
  • Milk
  • Orange Juice
  • Chewing Gum
  • Garlic & Onion

No Referral is Required in our clinic

Do you think you suffer from a food intolerance such as Lactose or Fructose or perhaps Small-intestinal bacterial overgrowth syndrome (SIBOS)?
There is a simple, accurate, pain free way to find out. It’s called Hydrogen Breath testing... and there are no blood tests!

Call 1300 263 257 to book

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