Beta-galactosidase, Bêta-Galactosidase, Lactasa.


Overview Information

Lactase is an enzyme. Like other enzymes, it is needed for a specific biochemical reaction in the body. The biochemical reaction that involves lactase breaks down lactose, a sugar in milk and milk products. Some people's bodies do not make enough lactase, so they are not able to digest milk well. These people are said to have "lactase deficiency" and are called "lactose intolerant." They can take supplemental lactase to help them break down lactose and tolerate milk. In these people lactase can prevent symptoms of lactose intolerance including cramps, diarrhea, and gas.

Some people take lactase by mouth for symptoms of lactose intolerance, including cramps, diarrhea, and gas.

In premature infants, lactase is taken by mouth to increase weight. Also, it is given to babies to reduce the symptoms of a disease called colic.

How does it work?

People who are lactose intolerant have trouble digesting the milk sugar lactose. Lactase is an enzyme that splits the milk sugar lactose, to produce the sugars glucose and galactose.


Uses & Effectiveness?

Likely Effective for

  • Preventing symptoms of lactose intolerance, such as cramps, diarrhea and gas, when milk products or lactose are taken by people with lactose intolerance. Taking lactase by mouth before consuming lactose or milk prevents gastrointestinal symptoms in people with lactose intolerance.

Insufficient Evidence for

  • A disease in babies called colic. Early research suggests that adding lactase to formula or breastmilk might decrease the amount of time that a baby with colic cries.
  • Infant development. Early research shows that adding lactase to formula or breastmilk does not increase weight gain in preterm infants.
Side Effects

Side Effects & Safety

When taken by mouth: Lactase is LIKELY SAFE for most people. It is an FDA-approved, nonprescription product available in the US. There are no reported side effects in clinical studies. But exposure to lactase might cause allergic reactions in some people.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Not enough is known about the use of lactase during pregnancy and breast-feeding. Stay on the safe side and avoid use.



We currently have no information for LACTASE Interactions.



The following doses have been studied in scientific research:


  • For lactose intolerance: the typical dose of lactase is 6000-9000 IU tablets chewed and swallowed at the start of a meal that contains lactose. 2000 IU of the solution added to 500 mL of milk immediately before drinking it has also been used.

View References


  • DairyEase product information. McNeil-PPC Inc. Fort Washington, PA 19034.
  • Erasmus HD, Ludwig-Auser HM, Paterson PG, Sun D, Sankaran K. Enhanced weight gain in preterm infants receiving lactase-treated feeds: a randomized, double-blind, controlled trial. J Pediatr. 2002;141(4):532-7. View abstract.
  • Horowitz M, Wishart J, Mundy L, Nordin BE. Lactose and calcium absorption in postmenopausal osteoporosis. Arch Intern Med 1987;147:534-6. View abstract.
  • Kanabar D, Randhawa M, Clayton P. Improvement of symptoms in infant colic following reduction of lactose load with lactase. J Hum Nutr Diet. 2001;14(5):359-63. View abstract.
  • Lami F, Callegari C, Tatali M, et al. Efficacy of addition of exogenous lactase to milk in adult lactase deficiency. Am J Gastroenterol 1988;83:1145-9.. View abstract.
  • Laukkanen A, Ruoppi P, Remes S, Koistinen T, Mäkinen-Kiljunen S. Lactase-induced occupational protein contact dermatitis and allergic rhinoconjunctivitis. Contact Dermatitis. 2007;57(2):89-93. View abstract.
  • Lin MY, Dipalma JA, Martini MC, et al. Comparative effects of exogenous lactase (beta-galactosidase) preparations on in vivo lactose digestion. Dig Dis Sci 1993;38:2022-7.. View abstract.
  • Newcomer AD, Hodgson SF, McGill DB, Thomas PJ. Lactase deficiency: prevalence in osteoporosis. Ann Intern Med 1978;89:218-20. View abstract.
  • Ramirez FC, Lee K, Graham DY. All lactase preparations are not the same: results of a prospective, randomized, placebo-controlled trial. Am J Gastroenterol 1994;89:566-70. View abstract.
  • Sanders SW, Tolman KG, Reitberg DP. Effect of a single dose of lactase on symptoms and expired hydrogen after lactose challenge in lactose-intolerant subjects. Clin Pharm 1992;11:533-8.. View abstract.
  • Spraycar M, ed. Stedman's Medical Dictionary. 26th ed. Baltimore, MD: Williams & Wilkins, 1995.

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CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.

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