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.

Natural Medicines Comprehensive Database 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.

The effectiveness ratings for LACTOBACILLUS ACIDOPHILUS are as follows:

Possibly effective for…

• 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.

Possibly ineffective for…

• 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.

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 children. It’s been used safely alone and together with other probiotics.

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.

Moderate

Be cautious with this combination.

Antibiotic drugs

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.

There are no known interactions with herbs and supplements.

There are no known interactions with foods.

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.

Acidophilus, Acidophilus Bifidus, Probiotic, Probiotique.

To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.

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