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Acidophilus (Lactobacillus acidophilus)


Also listed as: Lactobacillus acidophilus, Acidophilus
Related terms

Related Terms
  • Acidophilus, Acidophilus Extra Strength®, acidophilus milk, Acilact, Actimel®, DDS-Acidophilus, Enpac®, Florajen®, fresh poi, Gynoflor®, Kyo-Dophilus®, L-92, Lacteol Fort®, lactic acid bacteria mixture (Oxadrop® or AKSB), lactic acid-producing bacteria (LAB), Lacto Bacillus, Lactobacillaceae (family), Lactobacillus acidophilus spp., Lactobacillus acidophilus yogurt, Lactobacillus LB, Narine®, poi, Probiata®, probiotic, sour poi, yogurt.
  • Note: This monograph does not provide an in-depth analysis of L. acidophilus used in combination products. Separate monographs on probiotics or other species of Lactobacillus such as Lactobacillus GG (Lactobacillus rhamnosus) are available.

  • Lactobacillus acidophilus belongs to a group of bacteria that normally live in the human small intestine and vagina. L. acidophilus is one of the most commonly used probiotics, or "good germs." These are microorganisms that help to maintain a healthy intestinal tract and aid digestion. Common food sources of L. acidophilus include yogurt and fermented soy products, such as miso and tempeh.
  • Multiple human trials report benefits of L. acidophilus for bacterial vaginosis, a common infection of the vagina. L. acidophilus has long been used as a therapeutic agent for gastrointestinal disorders. However, this and other medicinal uses of L. acidophilus are not supported by strong clinical evidence.

Evidence Table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. GRADE *

Strong evidence supports the use of L. acidophilus to treat vaginal bacterial infections by applying L. acidophilus preparations directly to the affected area. More evidence is needed before a strong conclusion can be made.


Although not well studied in humans, some research has suggested that lactic acid-producing bacteria, such as L. acidophilus, may reduce allergic responses of the immune system. Further studies are needed before a conclusion can be made.


Research on the use of L. acidophilus for asthma is limited. Additional research is required before a conclusion can be made.


It is not clear whether L. acidophilus can prevent diarrhea in adults or children. Additional research is needed in this area.


It is unclear whether L. acidophilus (live or heat-killed, alone or in combination with other therapies) is effective in the treatment of diarrhea. Additional studies are needed before a firm conclusion can be made.


It is not clear whether L. acidophilus is effective in the treatment of eczema, although other bacteria related to L. acidophilus may be valuable. Additional research is needed before a conclusion can be made.


It is not clear whether L. acidophilus is effective in the treatment of H. pylori infection, although bacteria related to L. acidophilus may have value. Additional research is needed before a conclusion can be made.


Limited research suggests that L. acidophilus may be beneficial in the treatment of hepatic encephalopathy. Additional research is needed in this area.


In some studies, L. acidophilus was shown to have an effect on immune function. However, results are mixed. Additional research is needed.


Some studies suggest that L. acidophilus may be beneficial in the treatment of some intestinal conditions, such as irritable bowel syndrome (IBS), when used in combination with other therapies. Additional studies are needed to investigate the effect of L. acidophilus alone.


Although L. acidophilus and related bacteria are able to digest lactose, it is not clear whether supplementation with L. acidophilus is effective in the treatment of lactose intolerance. Additional research is needed before a firm conclusion can be made.


Overgrowth of bacteria in the vagina may be associated with premature birth. Some evidence suggests that L. acidophilus treatment may be helpful in preventing premature birth. Additional studies are needed in this area.


Some studies suggest that L. acidophilus, when used together with other probiotics, may aid in the treatment of high levels of cholesterol and other fats in the blood. Additional research is needed before a firm conclusion can be made.

* Key to grades

A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)

Tradition / Theory

The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

  • Acne, AIDS, breast cancer, cancer, canker sores, cavities, chemopreventive (disease-preventing), colon cancer, constipation, Crohn's disease, diaper rash, diverticulitis (formation of inflamed pouch in intestinal wall), . infection in cancer patients, fever blisters, gastric ulcer (prevention), heartburn, heart disease, hives, indigestion, infection, periodontal disease (gum disease), preoperative prevention of infections or gut bacteria loss, prostate cancer, thrush (yeast infection of the mouth), ulcerative colitis, urinary tract infection.


Adults (18 years and older)

  • L. acidophilus has been taken by mouth as capsules or tablets, clotted milk, fermented milk, a freeze-dried preparation, living or heat-killed bacteria, and yogurt. Treatments for vaginal disorders include: a douche made of yogurt and water; tablets containing L. acidophilus inserted directly into the vagina; a vaccine containing L. acidophilus.

Children (younger than 18 years)

  • L. acidophilus has been taken by mouth as capsules or tablets, clotted milk, freeze-dried bacteria, heat-killed bacteria, and a probiotic preparation.


The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.


  • Lactose-sensitive people may develop abdominal discomfort or other adverse effects from L. acidophilus-containing products, due to very small amounts of lactose left over from the manufacturing process. Avoid in patients with milk allergies.

Side Effects and Warnings

  • L. acidophilus is generally well tolerated with very few side effects.
  • Use with caution in infants, children, older patients, or patients with gastrointestinal disorders, short bowel syndrome, or high fever.
  • Avoid in patients with weakened immune systems or milk allergies.

Pregnancy and Breastfeeding

  • Lactobacillus GG has been used safely during pregnancy (2-4 weeks before delivery) and lactation (for up to six months). L. acidophilus has been studied in pregnant women for prevention of premature delivery.


Interactions with Drugs

  • L. acidophilus may interact with agents that reduce stomach acid, alcohol, antibiotics, birth control vaginal rings, cholesterol-lowering agents, gastrointestinal agents, sulfonamide drugs, and vaccines.

Interactions with Herbs and Dietary Supplements

  • L. acidophilus may interact with antibacterials, cholesterol-lowering herbs and supplements, gastrointestinal herbs and supplements, low-oxalate diets, phytic acid, prebiotics, and probiotics.

  • This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

  1. Andrade S, Borges N. Effect of fermented milk containing Lactobacillus acidophilus and Bifidobacterium longum on plasma lipids of women with normal or moderately elevated cholesterol. J Dairy Res 2009;76(4):469-74.
  2. Azcarate-Peril MA, Tallon R, Klaenhammer TR.Temporal gene expression and probiotic attributes of Lactobacillus acidophilus during growth in milk. J Dairy Sci 2009;92(3):870-86.
  3. Baldwin C, Millette M, Oth D, et al. Probiotic Lactobacillus acidophilus and L. casei mix sensitize colorectal tumoral cells to 5-fluorouracil-induced apoptosis. Nutr Cancer 2010;62(3):371-8.
  4. Chassot F, Camacho DP, Patussi EV, et al. Can Lactobacillus acidophilus influence the adhesion capacity of Candida albicans on the combined contraceptive vaginal ring? Contraception 2010;81(4):331-5.
  5. Chitapanarux I, Chitapanarux T, Traisathit P, et al. Randomized controlled trial of live lactobacillus acidophilus plus bifidobacterium bifidum in prophylaxis of diarrhea during radiotherapy in cervical cancer patients. Radiat Oncol 2010;5:31.
  6. Gao XW, Mubasher M, Fang CY, et al. Dose-response efficacy of a proprietary probiotic formula of Lactobacillus acidophilus CL1285 and Lactobacillus casei LBC80R for antibiotic-associated diarrhea and Clostridium difficile-associated diarrhea prophylaxis in adult patients. Am J Gastroenterol 2010;105(7):1636-41.
  7. Hayes M, Barrett E, Ross RP, et al. Evaluation of an antimicrobial ingredient prepared from a Lactobacillus acidophilus casein fermentate against Enterobacter sakazakii. J Food Prot 2009;72(2):340-6.
  8. Huang Y, Zheng Y. The probiotic Lactobacillus acidophilus reduces cholesterol absorption through the down-regulation of Niemann-Pick C1-like 1 in Caco-2 cells. Br J Nutr 2010;103(4):473-8.
  9. Kim JY, Kwon JH, Ahn SH, et al. Effect of probiotic mix (Bifidobacterium bifidum, Bifidobacterium lactis, Lactobacillus acidophilus) in the primary prevention of eczema: a double-blind, randomized, placebo-controlled trial. Pediatr Allergy Immunol 2010;21(2 Pt 2):e386-93.
  10. Lin PP, Hsieh YM, Tsai CC. Antagonistic activity of Lactobacillus acidophilus RY2 isolated from healthy infancy feces on the growth and adhesion characteristics of enteroaggregative Escherichia coli. Anaerobe 2009;15(4):122-6.
  11. Mkrtchyan H, Gibbons S, Heidelberger S, et al. Purification, characterisation and identification of acidocin LCHV, an antimicrobial peptide produced by Lactobacillus acidophilus n.v. Er 317/402 strain Narine. Int J Antimicrob Agents 2010;35(3):255-60.
  12. Patrignani F, Burns P, Serrazanetti D, et al. Suitability of high pressure-homogenized milk for the production of probiotic fermented milk containing Lactobacillus paracasei and Lactobacillus acidophilus. J Dairy Res 2009;76(1):74-82.
  13. Silva MR, Dias G, Ferreira CL, et al. Growth of preschool children was improved when fed an iron-fortified fermented milk beverage supplemented with Lactobacillus acidophilus. Nutr Res 2008;28(4):226-32.
  14. Sinn DH, Song JH, Kim HJ, et al. Therapeutic effect of Lactobacillus acidophilus-SDC 2012, 2013 in patients with irritable bowel syndrome. Dig Dis Sci 2008;53(10):2714-8.
  15. Vissers YM, Snel J, Zuurendonk PF, et al. Differential effects of Lactobacillus acidophilus and Lactobacillus plantarum strains on cytokine induction in human peripheral blood mononuclear cells. FEMS Immunol Med Microbiol 2010;59(1):60-70.

Copyright © 2011 Natural Standard (

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

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