Lactobacillus acidophilus
Lactobacillus acidophilus


Lactobacillus acidophilus (L. acidophilus) is a type of probiotic ("good" bacteria) found in the human gut, mouth, and vagina, and also in certain foods.

"Good" bacteria such as L. acidophilus can help break down food, absorb nutrients, and fight off "bad" organisms that might cause diseases. L. acidophilus is sometimes added to fermented foods like yogurt and is also found in probiotic supplements.

People commonly use L. acidophilus for diarrhea from antibiotics, as well as irritable bowel syndrome (IBS), overgrowth of bacteria in the vagina, and an infection caused by the bacteria Helicobacter pylori (H. pylori). It is also used for acne, hay fever, eczema, and many other conditions, but there is no good scientific evidence to support many of these other uses. There is also no good evidence to support using L. acidophilus COVID-19.

Don't confuse L. acidophilus with other probiotics, or with fermented food products such as fermented milk, kefir, or yogurt. These are not the same. Also note that the Lactobacillus genus was split up into 25 different genera in April 2020. Some other species' names changed, but L. acidophilus remained the same.
When taken by mouth: L. acidophilus is likely safe. It's been used safely together with other probiotics for up to 9 months. Some people might experience gas or bloating, but it's usually well-tolerated.

When applied to the vagina: L. acidophilus is likely safe. It's been used safely for up to 12 weeks.

Special Precautions & Warnings:

Pregnancy: L. acidophilus is possibly safe when taken by mouth during pregnancy. It's been used safely together with other probiotics for 6 weeks, starting at 24-28 weeks of pregnancy.

Breast-feeding: There isn't enough reliable information to know if L. acidophilus is safe to use while breast-feeding. But there's no reason to expect safety concerns when used appropriately under medical supervision.

Children: L. acidophilus is likely safe when taken by mouth appropriately in most children. It's been used safely alone and together with other probiotics. However, there isn't enough reliable information to know if L. acidophilus is safe for very small premature infants.

Weakened immune system: Some probiotics have caused blood infections in a small number of people with weakened immune systems. If you have a weakened immune system, talk with your healthcare provider before taking probiotics, including L. acidophilus.

Damaged heart valves: Some probiotics have caused infections of the inner lining of the heart chambers and heart valve. This is extremely rare, but people with damaged heart valves should stop taking probiotics like Lactobacillus acidophilus before dental procedures or surgical procedures.


NatMed Pro rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
Likely effective Effectiveness definitions
Possibly effective Effectiveness definitions
  • Diarrhea in people taking antibiotics (antibiotic-associated diarrhea). Taking L. acidophilus by mouth, alone or with other probiotics, seems to reduce the risk of diarrhea while taking antibiotics.
  • Overgrowth of bacteria in the vagina. L. acidophilus vaginal suppositories and vaginal tablets might help treat this condition. But it's not clear if taking L. acidophilus by mouth helps.
  • A digestive tract infection that can lead to ulcers (Helicobacter pylori or H. pylori). Taking L. acidophilus by mouth along with most standard drug therapies helps treat stomach ulcers caused by H. pylori.
  • A long-term disorder of the large intestines that causes stomach pain (irritable bowel syndrome or IBS). Taking L. acidophilus by mouth with other probiotics seems to reduce symptoms of IBS.
Likely ineffective Effectiveness definitions
Possibly ineffective Effectiveness definitions
  • Prone to allergies and allergic reactions (atopic disease). Taking L. acidophilus by mouth during pregnancy, while breastfeeding, or giving it to newborns doesn't seem to prevent allergies in children.
There is interest in using L. acidophilus for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.
Insufficient evidence Effectiveness definitions

Dosing & administration

L. acidophilus is sometimes added to fermented foods such as yogurt, but it's most commonly used in dietary supplements.

In adults, L. acidophilus has most often been taken by mouth, alone or together with other probiotics, in doses of up to 60 billion CFUs daily for up to 6 months. In children, L. acidophilus has most often been taken by mouth in doses of up to 30 billion CFUs daily, for up to 3 months. Speak with a healthcare provider to find out what dose might be best for a specific condition.

Interactions with pharmaceuticals

Antibiotic drugs

Interaction Rating=Moderate Be cautious with this combination.

L. acidophilus is a type of friendly bacteria. Antibiotics are used to reduce harmful bacteria in the body. Taking antibiotics along with L. acidophilus can reduce the effects of L. acidophilus. To avoid this interaction, take L. acidophilus products at least 2 hours before or after antibiotics.

Interactions with herbs & supplements

There are no known interactions with herbs and supplements.

Interactions with foods

There are no known interactions with foods.
Plus Double Strength
RRP: $69.95$47.56Save: 32%
Sold out
Create account
return unknown
Ultra Flora Spectrum
Practitioner product
ProBiotica Daily Health
RRP: $45.99$35.87Save: 22%
Create account
RRP: $53.96$36.69Save: 32%
Sold out
Create account
return unknown
RRP: $36.95$25.12Save: 32%
Create account
Plus Dairy Free
RRP: $86.96$59.13Save: 32%
Sold out
Create account
return unknown
Ultra Flora Restore
Practitioner product
UltraBiotic Immune Support for Juniors
Practitioner product has licensed monographs from TRC Healthcare.
This monograph was last reviewed on 19/02/2024 11:00:00 and last updated on 18/11/2020 02:23:18. Monographs are reviewed and/or updated multiple times per month and at least once per year.
Natural Medicines disclaims any responsibility related to medical consequences of using any medical product. Effort is made to ensure that the information contained in this monograph is accurate at the time it was published. Consumers and medical professionals who consult this monograph are cautioned that any medical or product related decision is the sole responsibility of the consumer and/or the health care professional. A legal License Agreement sets limitations on downloading, storing, or printing content from this Database. No reproduction of this monograph or any content from this Database is permitted without written permission from the publisher. It is unlawful to download, store, or distribute content from this site.