Lactase

Lactase enzyme · Beta-galactosidase supplement

Snapshot

Indications	Contraindications
Lactose intolerance^1–4 Lactose malabsorption⁵ Infantile colic⁶ Lactose intolerance in preterm infants⁷	Wheat allergy⁸ Soy allergy⁸

Lactase is the small-intestine enzyme that splits lactose, and oral supplements stand in for it so undigested lactose does not reach colonic fermentation. Supplementation is used for lactose intolerance in lactase nonpersistent adults, a trait common across much of Asia and Africa⁹. It is also given as drops for infantile colic and for feeding intolerance in preterm infants.

Evidence in infant colic is split: a 2022 trial found shorter crying, while two 2024 systematic reviews judged the evidence inconclusive. A Cochrane review found no significant benefit in preterm infants from the single trial available¹⁰. In adults with the lactase nonpersistent genotype, a 2024 before-and-after trial found graded daily lactose raised Bifidobacterium and lowered breath hydrogen¹¹. Products listing lactase number 4796, mostly capsules, softgels, and liquid drops; see Form comparison.

Some United States product labels declare wheat or soy⁸. Inhaled lactase caused immunoglobulin E (IgE)-mediated respiratory sensitization in tablet manufacturing workers¹².

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

45 sources, 35 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources