Reviewed on 6/11/2021
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Galacto-oligosaccharides are made up of plant sugars linked in chains. They are taken from dairy products, beans, and certain root vegetables. People use these sugars to make medicine.

Galacto-oligosaccharides are used for hay fever (allergic rhinitis), asthma, itchy skin (eczema), infant colic, colon and rectal cancer, constipation, Crohn's disease, diarrhea, digestive disorders, flu, food allergies, infant development, irritable bowel syndrome, osteoporosis, a bowel disease called ulcerative colitis, and a condition called pouchitis, which can develop after surgery for ulcerative colitis.

Galacto-oligosaccharides are also used as prebiotics. Prebiotics act as food for “good” bacteria in the intestine. Don't confuse prebiotics with probiotics such as lactobacillus, bifidobacteria, and saccharomyces, which are live organisms that are good for health. People sometimes take probiotics by mouth to increase the number in their intestine.

In foods, galacto-oligosaccharides are used as a sweetener.

How does it work?

Galacto-oligosaccharides pass undigested into the colon where they increase bowel mass and promote growth of certain bacteria that are thought to be beneficial.


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Uses & Effectiveness

Possibly Effective for...

  • Scaly, itchy skin (eczema). Some research shows that feeding infants at risk for allergy galacto-oligosaccharides and probiotics decreases the risk of developing eczema by the age of 2 years. Also, feeding newborns at risk for eczema formula containing galacto-oligosaccharides and fructo-oligosaccharides appears to reduce the risk of developing eczema. However, other research shows that feeding healthy infants a formula containing galacto-oligosaccharides does not affect the risk of developing eczema.
  • Colic. Research shows that feeding infants with colic a formula that contains galacto-oligosaccharides and fructo-oligosaccharides reduces the number of colic episodes compared to control formula plus the drug simethicone.

Possibly Ineffective for...

  • Hay fever (allergic rhinitis). Some research shows that feeding infants at risk for allergy a combination of galacto-oligosaccharides and probiotics does not reduce the risk of developing hay fever by the age of 2 years.
  • Asthma. Some research shows that feeding infants at risk for allergy a combination of galacto-oligosaccharides and probiotics does not reduce the risk of developing asthma by the age of 2 years.
  • Food allergies. Some research shows that feeding infants at risk for allergy a combination of galacto-oligosaccharides and probiotics does not reduce the risk of developing food allergies by the age of 2 years.
  • Infant development. Research shows that adding galacto-oligosaccharides to infant formula does not affect how quickly a healthy infant gains weight or increases in length.

Insufficient Evidence to Rate Effectiveness for...

More evidence is needed to rate the effectiveness of galacto-oligosaccharides for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

Side Effects

Galacto-oligosaccharides are POSSIBLY SAFE when taken in doses of less than 20 grams per day. They can cause intestinal gas (flatulence), bloating, stomach cramps, and diarrhea.


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Special Precautions & Warnings

Pregnancy and breast-feeding: Galacto-oligosaccharides are POSSIBLY SAFE when taken in doses of less than 4.5 grams per day beginning at 25 weeks gestation and continuing until delivery. There is not enough reliable information about the safety of taking galacto-oligosaccharides if you are breast-feeding. Stay on the safe side and avoid use.

Children: Galacto-oligosaccharides are POSSIBLY SAFE when added to formula at concentrations of less than or equal to 8 grams/L.

“Auto-immune diseases” such as multiple sclerosis (MS), lupus (systemic lupus erythematosus, SLE), rheumatoid arthritis (RA), or other conditions: Galacto-oligosaccharides might cause the immune system to become more active. This might increase the symptoms of auto-immune diseases. If you have an auto-immune condition, it's best to avoid using galacto-oligosaccharides as medicine until more is known.


Medications that decrease the immune system (Immunosuppressants)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Galacto-oligosaccharides might make the immune system more active. Taking galacto-oligosaccharides along with medications that decrease the immune system might decrease the effectiveness of these medications.

Some medications that decrease the immune system include azathioprine (Imuran), basiliximab (Simulect), cyclosporine (Neoral, Sandimmune), daclizumab (Zenapax), muromonab-CD3 (OKT3, Orthoclone OKT3), mycophenolate (CellCept), tacrolimus (FK506, Prograf), sirolimus (Rapamune), prednisone (Deltasone, Orasone), and other corticosteroids (glucocorticoids).


The following doses have been studied in scientific research:


  • For preventing eczema in children: 20 drops of syrup containing 0.8 grams of galacto-oligosaccharides, along with a capsule of probiotics, daily for 6 months; formula containing 0.8 grams/L of galacto-oligosaccharides and fructo-oligosaccharides daily as needed for 6 months.
  • For colic: formula containing 8 grams/L of a mixture of galacto-oligosaccharides (90%) and fructo-oligosaccharides (10%) daily as needed for 2 weeks.

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