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Woman collecting breath for lactulose SIBO breath test

Breath Testing for SIBO

Prepare for your small intestinal bacteria overgrowth (SIBO) test by reviewing this page and watching the videos.

The Hydrogen/Methane breath test with lactulose challenge is used to diagnose SIBO. Collection for this test can be performed at home using an at-home collection kit or at the clinic on select days. 


 A 1-2 day preparation diet is required. It may also be necessary to stop taking select medications. This will be determined by your doctor.

At-Home or Supervised In-Clinic Collection Available

In-clinic testing on select dates only. Space is limited. Call to reserve your spot.




If you are not able to comply with these guidelines for testing, you may not be a candidate for a breath test and your doctor can assist you in determining if another test without these preparation limits is more suitable.

  • No antibiotics or anti-fungals 2 WEEKS (14 days) BEFORE TESTING. Finish taking any antibiotics or anti-fungals (except those who are re-testing following SIBO treatment).

  • WAIT TWO WEEKS (14 days) after surgery, colonoscopy, enemas, or colonics.

  • 4 DAYS BEFORE YOUR TEST avoid all laxatives. This includes (high dose) vitamin C and magnesium that is being taken specifically to induce a laxative effect.
  • No fermented foods 1 day before testing.

  • No smoking, including second-hand smoke, for at least 1 hour before or at any time during the breath test.
  • No sleeping or vigorous exercise for at least 1 hour before or at any time during the breath test.


Before you start the breath test, a 24-48 hour preparation is required consisting of a 1-2 day (12-36 hour) restricted diet and a 12 hour fasting period (stop eating in the early evening the day before testing and do not eat until after you test the following morning).

If you are uncertain if something will affect the test, avoid the product/ food or consult your physician prior to starting the test.


If you suffer from constipation, follow the SIBO preparation diet for 2 days (36 hours). If you suffer from diarrhea, follow the SIBO preparation diet for 1 day (12 hours).

The first 12 or 36 hours is the restricted diet.  Limit your foods and beverages to those below and nothing else:

  • You may drink plain water, coffee, tea (no sugar/artificial sweeteners or cream added)

  • Baked or broiled chicken, fish or turkey. (Salt and pepper only)

  • Plain steamed white rice
  • Eggs

  • Clear chicken or beef broth (meat broth not bones with cartilage)

The goal of the SIBO preparation diet is to starve your bacteria for a day in order to produce the best test results. SIBO bacteria love plant products and sugars, so the only foods that you can have on the those listed above – if it is not on this list DO NOT eat it.


Stop eating the evening before the morning of your test; similar to a fasting blood draw.  ​The last 12 hours DO NOT eat or drink anything, except water.


What is lactulose?

Lactulose is a man-made sugar that humans cannot digest. However, SIBO bacteria love it, and it acts like fertilizer for them. This will allow us to get an accurate read of their presence in the small intestines.


Drinking lactulose will not cause a “sugar-high” like sugars that humans can digest (sucrose or fructose). Lactulose can have a laxative effect, so some people may need to have a restroom nearby during the test. Also, SIBO symptoms such as bloating and gas may increase temporarily for some people.

Is lactulose the same as lactose?

No. Lactose is the sugar from milk. Lactulose is a completely different chemical makeup that is man-made. The lactulose that comes in the SIBO kits is a liquid solution. This solution, however, does contain 1.2 grams of lactose in it, so people who are severely lactose intolerant should ask their doctor if this test is right for them.


Which medications will affect the outcome of a hydrogen breath test?

  • Narcotics- Do not take these the day of the test

  • Laxatives (such as Metamucil, Dulcolax, Ex-Lax)- Stop taking 1-4 days before taking the test

  • Antibiotics- Stop taking 4 weeks before taking test (in some cases 2-weeks)

  • Probiotics- Stop taking 1-4 days before taking test

Can I use seasoning during the restricted SIBO prep diet?

The only seasonings allowed are salt and pepper used in moderation.

Can I chew gum during the SIBO breath test preparation period?

No, gum is not allowed during any part of the preparation period.


How do I return an at-home breath test collection kit?

Kits mailed to patients will include return shipping labels for the United States Postal Service. The gas tubes are highly stable therefore regular shipping is recommended. Sample must be received within 7-days of collection​.

If you live near our offices in Stillwater, MN, you may drop off your collection kit at the office.

How long does breath test collection take?

Breath test collection requires 3-4 hours. Please plan accordingly.

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