Lactose Intolerance and Lactase Supplements: What Is Known About How Well They Work
How well lactase supplements work for lactose intolerance: what the term means, what small trials and a review found, where the evidence stops, and who should ask a clinician first.
Content last updated . This page has not been medically reviewed.
How the sources define the terms
NIDDK defines lactose intolerance as digestive symptoms, such as bloating, diarrhea and gas, after consuming foods or drinks that contain lactose. [1] It is caused by lactose malabsorption, where the small intestine cannot digest all the lactose eaten, and not everyone with malabsorption has symptoms. [1] NIDDK says experts estimate about 68 percent of the world's population has lactose malabsorption, and about 36 percent of people in the United States. [1] It is different from a milk allergy, which is an immune system disorder. [1]Evidence labels: established use, promising but limited, mixed, insufficient evidence, Proper evidence not found. Amounts in studies are study amounts, not advice.
What research and official bodies found
| Question | What the source found | Strength |
|---|---|---|
| Do health agencies describe lactase products? | NIDDK describes tablets or drops that contain lactase. [2] The NHS says a lactase supplement may reduce or prevent symptoms for some people. [3] | Established use (agency descriptions) |
| Do chewable tablets reduce symptoms after a lactose challenge? | A crossover trial in 47 adults confirmed by breath test reported lower symptoms and a 55% lower cumulative breath hydrogen than placebo. [4] A 1992 single-dose crossover in 24 adults reported lower hydrogen and several lower symptom ratings. [5] | Promising but limited |
| Does the amount of lactose matter? | With 20 g of lactose, three lactase products reduced hydrogen and symptoms; with 50 g, the effect was modest and not significant. [6] | Mixed |
| Does lactase help young children? | A trial in 50 children aged 6 to 24 months with persistent diarrhea and secondary lactose intolerance found fewer diarrhea episodes on day five with lactase drops than with lactose-free formula (20.0% vs 48.0%). [7] | Insufficient evidence (one hospital trial in a sick population) |
| Does lactase help infant colic? | A 2024 systematic review of five trials (391 infants) called the evidence inconclusive. [8] | Insufficient evidence |
| Do probiotics or prebiotics treat lactose intolerance? | A 2025 review said their effectiveness had not yet been proven. [9] | Insufficient evidence |
Diet is the first-line approach in the sources. NIDDK says many people could have 12 grams of lactose, about 1 cup of milk, with no or only mild symptoms, and may tolerate small amounts with meals, yogurt and hard cheeses. [10] Lactose-free and lactose-reduced products may help lower lactose intake. [10] See yogurt for fermented dairy.
Frequently asked questions
Do lactase supplements really work?
In small crossover trials, chewable lactase lowered symptoms and breath hydrogen after a lactose challenge, but a larger lactose load overwhelmed the amounts tested in one study. [4][6]
How is lactose intolerance diagnosed?
The NHS says a GP may suggest a lactose elimination diet, blood tests or a hydrogen breath test. [3]
Should I give lactase drops to my baby?
Ask a pediatrician first. A 2024 systematic review found the evidence for infant colic inconclusive. [8]
Can probiotics replace lactase?
Not on current evidence; a 2025 review said probiotics and prebiotics have not yet been proven effective for lactose intolerance. [9]
Is lactose intolerance the same as a milk allergy?
No. Milk allergy is an immune system disorder, and the NHS describes signs of a serious allergic reaction. [1][3]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Limits and uncertainty
- The trials above are short challenge studies, mostly in small groups; they do not show long-term benefit or benefit for every meal.
- The trials tested specific products and amounts; do not assume another product behaves the same way.
- No treatment can raise the lactase your small intestine makes in lactase nonpersistence or congenital lactase deficiency. [2]
- Effect sizes for typical daily use: Proper evidence not found (we searched PubMed for randomized trials and systematic reviews of lactase supplements).
Safety and who should ask a clinician
- NIDDK says to check with your doctor before using lactase products, and that young children and pregnant and breastfeeding women may not be able to use them. [2] See pregnancy and breastfeeding safety and children and teens.
- Lactose intolerance can follow another condition; the NHS lists inflammatory bowel disease, coeliac disease, bowel infections, surgery or injury, and says treating the underlying cause should help. [3]
- The NHS says to see a GP if symptoms keep coming back, or you have blood in your poo for 3 weeks, bloating and discomfort for 3 weeks, or unexplained weight loss. [3]
- The NHS says not to cut foods from your or your child's diet without advice from a GP or dietitian. [3]
- Calcium and vitamin D can fall short if you avoid all milk products. [10] See calcium.
- Medicine interactions: Proper evidence not found in the sources we read. Ask a pharmacist; see how interactions work. Mention lactase to your surgical team as with any supplement.
For the symptom guide see lactose intolerance; for the enzyme basics see lactase and alpha-galactosidase.
References
- NIDDK. Definition & Facts for Lactose Intolerance. Last reviewed February 2018. Read 2026-10-22.
- NIDDK (US National Institute of Diabetes and Digestive and Kidney Diseases). Treatment for Lactose Intolerance. Last reviewed February 2018. Read 2026-10-22.
- NHS (UK). Lactose intolerance. Page last reviewed 8 July 2026. Read 2026-10-22.
- Baijal R, Tandon RK. Effect of lactase on symptoms and hydrogen breath levels in lactose intolerance: A crossover placebo-controlled study. JGH Open 2020. PMID 33490624. Read 2026-10-22.
- Sanders SW et al. Effect of a single dose of lactase on symptoms and expired hydrogen after lactose challenge in lactose-intolerant subjects. Clin Pharm 1992. PMID 1534729. Read 2026-10-22.
- Lin MY et al. Comparative effects of exogenous lactase (beta-galactosidase) preparations on in vivo lactose digestion. Dig Dis Sci 1993. PMID 8223076. Read 2026-10-22.
- Siddiqi FG et al. Comparison of the effectiveness of oral lactase enzyme and lactose-free formula in the management of secondary lactose intolerance in persistent and severe persistent diarrhea. Pak J Med Sci 2026. PMID 42668931. Read 2026-10-22.
- Kozlowska-Jalowska A et al. Effect of lactase supplementation on infant colic: Systematic review of randomized controlled trials. J Pediatr Gastroenterol Nutr 2024. PMID 38426798. Read 2026-10-22.
- Borralho AI, Marcos P. Lactose Intolerance and Malabsorption Revisited: Exploring the Impact and Solutions. GE Port J Gastroenterol 2025. PMID 40432984. Read 2026-10-22.
- NIDDK. Eating, Diet, & Nutrition for Lactose Intolerance. Last reviewed February 2018. Read 2026-10-22.