What Is Lactobacillus Acidophilus?

A bacteria that promotes gut health and helps prevent infections

Lactobacillus acidophilus (L. acidophilus) is a type of bacteria found naturally in your gastrointestinal tract and other parts of your body.

Lactobacillus acidophilus belongs to the Lactobacillus family of bacteria. It is naturally found in some foods but can also be used in supplement form for various health conditions.

It is commonly used as a probiotic. Like other probiotics, L. acidophilus is thought to help balance bacteria in the gut so that potentially harmful strains will not flourish.

This article discusses the potential uses of L. acidophilus and the science behind them. It also covers side effects, precautions, interactions, dosage, and proper storage of L. acidophilus.

Dietary supplements are not regulated like drugs in the United States, meaning the Food and Drug Administration (FDA) does not approve them for safety and effectiveness before products are marketed. When possible, choose a supplement tested by a trusted third party, such as USP, ConsumerLabs, or NSF. 

However, even if supplements are third-party tested, that doesn’t mean they are necessarily safe for all or effective in general. Therefore, it is important to talk to your healthcare provider about any supplements you plan to take and check in about potential interactions with other supplements or medications.

Supplement Facts

  • Active ingredient(s): Lactobacillus acidophilus
  • Alternate name(s): L. acidophilus, Acidophilus, Acidophilus Bifidus
  • Legal status: Legal in the U.S. and available over-the-counter.
  • Suggested dose: Dosage typically varies but may be as high as 60 billion colony forming units (CFUs) per day for up to six months in adults.
  • Safety considerations: Side effects may include gas and bloating.
Sauerkraut, cucumber pickles and yogurt
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Uses of Lactobacillus Acidophilus

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease. 

In complementary alternative medicine, L. acidophilus has many uses. It is sometimes used to prevent or treat several health conditions, like diarrhea, irritable bowel syndrome (IBS), and bacterial vaginosis. It is also commonly used as a probiotic for gut health.

Although L. acidophilus is one of the more extensively studied probiotics, findings have varied widely due to differences in patient populations, bacteria strains, and other factors.

What follows is a look at some findings from the available research on the benefits of L. acidophilus.


Your healthcare provider may recommend L. acidophilus to treat diarrhea, which is characterized by loose and/or frequent stools.

A 2020 review on the use of L. acidophilus for digestive disorders found it to be both safe and effective in treating diarrhea. Researchers concluded that L. acidophilus could be useful as a complementary treatment for both acute diarrhea and chronic diarrhea, as well as diarrhea caused by antibiotics.

Another recent review noted the ability of L. acidophilus to reduce the duration of diarrhea in children. After looking at 15 trials, researchers from the review found that children who used L. acidophilus had shorter bouts of diarrhea compared to those who took a placebo.

Irritable Bowel Syndrome

Probiotics such as L. acidophilus have also been used for irritable bowel syndrome (IBS).

A review of L. acidophilus found some evidence that the bacteria strain could reduce abdominal pain and discomfort in those with IBS. However, the review also noted that not all human trials on L. acidophilus for IBS had proven positive results. In fact, some studies have found L. acidophilus to have unwanted side effects in those with IBS.

Additionally, a recent randomized controlled trial found L. acidophilus helped reduce IBS-associated abdominal pain and symptom severity more than a placebo.

Vaginal Health

L. acidophilus may be helpful in the prevention and treatment of vaginal infections, including bacterial vaginosis (BV) and yeast infections.

According to one review, daily intake of L. acidophilus supplements may help prevent and treat BV, a common vaginal infection that results from an imbalance in the types of bacteria in the vagina.

Like other strains of the Lactobacillus family, L. acidophilus is thought to have antimicrobial properties that make it a potentially useful treatment for BV.

L. acidophilus may also have antifungal properties, making it a potential treatment for yeast infections. Laboratory research shows that L. acidophilus and other probiotics may inhibit the growth of the fungus Candida albicans, which is a common culprit of yeast infections.

A 2015 clinical trial found L. acidophilus may help lower the risk of recurring yeast infections following standard medical treatment.

In the study, 436 people assigned female at birth with vaginal yeast infections were treated with the antifungal fenticonazole. Five days later, roughly half the study participants were given multiple intravaginal L. acidophilus treatments. Those given the probiotic had a significant reduction in recurring infections.

Immune Health

L. acidophilus is thought to have antimicrobial and antiviral properties. These properties may make L. acidophilus a treatment option for cold symptoms in children.

A study published in the journal Pediatrics found that six months of daily L. acidophilus use reduced fever by 53%, coughing by 41%, antibiotic use by 68%, and days absent from school by 32% in children ages 3 to 5. Interestingly, combining L. acidophilus with a broad spectrum of probiotics was found to be even more effective.

Consult a healthcare provider before using L. acidophilus for any purpose to determine if it is an appropriate supplement for you.

What Are the Side Effects of Lactobacillus Acidophilus?

Although generally considered safe, using L. acidophilus may cause mild or severe side effects.

Common Side Effects

Many studies on L. acidophilus have reported little to no adverse events.

When side effects do occur, they tend to be mild. Side effects of L. acidophilus include digestive complaints, like gas and bloating.

If side effects do not improve or worsen, you should discontinue L. acidophilus and consult a healthcare provider.

Severe Side Effects

Although rare, severe side effects may occur when using L. acidophilus

There is thought to be a minor risk of infection related to the use of L. acidophilus.

Probiotics like L. acidophilus have caused blood infections in some people with weakened immune systems. There is also a low risk of infection of the inner lining of the heart (endocarditis) from taking probiotics, including L. acidophilus.

You should always speak with a healthcare provider before starting a new supplement, especially if you have a weakened immune system or other health conditions. A healthcare provider can also help you determine the proper supplement dose, which may lower your risk of side effects.


Some people may need to take special precautions when using L. acidophilus.

L. acidophilus is thought to be safe for those who are pregnant or breastfeeding, as long as it is used appropriately. For this reason, people who are pregnant or breastfeeding should speak to a healthcare provider before taking L. acidophilus.

Due to a greater risk of adverse events and complications, those with a weakened immune system should seek medical advice before taking L. acidophilus.

Likewise, you should seek guidance before taking L. acidophilus if you have a damaged heart valve. Although rare, there is a minimal risk of infection of the inner lining of the heart from taking L. acidophilus.

Dosage: How Much Lactobacillus Acidophilus Should I Take?

Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs. 

In adults, L. acidophilus is often taken in doses of up to 60 billion colony-forming units (CFUs) per day. Typically, L. acidophilus is taken for up to six months.

Children should take smaller doses of up to 30 billion CFUs daily for no more than three months.

Please follow the directions on the supplement packaging or check with your or your child's healthcare provider for an appropriate L. acidophilus dose.

What Happens If I Take Too Much Lactobacillus Acidophilus?

Although L. acidophilus is generally considered safe, it has not been well tested for safety. And, like most other supplements, it has not been approved by the Food and Drug Administration (FDA) as a treatment for health conditions.

While there are no well-documented reports regarding the toxicity of L. acidophilus, taking too much of any supplement or probiotic could increase your risk of side effects.

If you take too much L. acidophilus, you may find yourself experiencing common side effects like gas and bloating.

Remember to talk with your healthcare provider about proper L. acidophilus dosage.


It's important to be aware of any medications, supplements, or foods that may negatively interact with L. acidophilus.

For the most part, L. acidophilus is thought to have few, if any, interactions.

Antibiotics may reduce the effectiveness of L. acidophilus. To avoid this interaction, antibiotics should be taken at least two hours apart from L. acidophilus.

In lab and animal studies, a potential interaction between L. acidophilus and sulfasalazine has been reported. Taking L. acidophilus along with sulfasalazine may increase certain by-products of the medication in your blood. However, this interaction has not been reported in humans.

Before choosing an L. acidophilus supplement, carefully read the ingredient list and nutrition facts panel to know which ingredients and how much of each ingredient is included. Please review this supplement label with your healthcare provider to discuss any potential interactions with foods, other supplements, and medications. 

How to Store Lactobacillus Acidophilus

Depending on the manufacturing processes, you may find some L. acidophilus products need refrigeration, while others are shelf-stable. Be sure to store probiotics as directed on the label and minimize contact with air. 

Supplements should be stored in a cool, dry place and kept out of direct sunlight. They should also be kept out of reach of pets and small children.

Any remaining L. acidophilus supplements should be discarded once they reach their expiration date.

Similar Supplements

Research suggests that L. acidophilus may be used for gut health, vaginal health, and immune health. However, L. acidophilus is not the only supplement thought to do so.

Supplements that are similar to L. acidophilus include:

  • Saccharomyces boulardii: Another type of probiotic, Saccharomyces boulardii (S. boulardii) has shown positive results when used to treat pediatric diarrhea. In infants and young children, S. boulardii supplementation has been found to decrease both the duration and severity of acute diarrhea.
  • Tea tree oil: Tea tree oil may possess anti-fungal properties, making it a possible option for fighting yeast infections. In one study, tea tree oil improved the effects of a conventional medication used to treat a yeast infection. However, these results have yet to be repeated in humans.
  • Vitamin D: Vitamin D, or the sunshine vitamin, may play a role in treating the common cold. In various studies, vitamin D supplementation has been linked to cold and respiratory tract infection prevention. However, other studies have shown mixed results.

Consult your healthcare provider about which supplement is right for you.

Frequently Asked Questions

  • Can you take L. acidophilus every day?

    While you can take L. acidophilus daily, little is known about how long it is safe to take the probiotic.

    We know it is safe to use L. acidophilus for up to nine months. However, it is unclear if L. acidophilus can be safely used beyond that timeframe.

    For best practice, talk with your healthcare provider about how long you can safely take daily doses of L. acidophilus.

  • What are the side effects of probiotics?

    Side effects of probiotics mostly include digestive complaints.

    Gas is a common side effect of taking probiotics, but you also may experience bloating, upset stomach, or diarrhea, especially in the beginning. Some people have reported more severe side effects like infections or fungus in the blood due to using probiotics.

  • How much L. Acidophilus should I take?

    In adults, L. acidophilus is typically taken in doses of up to 60 billion colony forming units (CFUs) per day. Children should take smaller doses, not exceeding 30 billion colony forming units per day.

    Your healthcare provider can help you determine the right L. acidophilus dose for you.

Sources of Lactobacillus Acidophilus & What to Look For

Although mostly found in supplements, L. acidophilus can also be found in a few foods.

And while both methods are thought to be beneficial in various ways, a food-first approach to nutrients (including probiotics) is always preferred. There is no solid evidence that probiotic foods are superior to probiotic supplements, but food forms of L. acidophilus may be preferred.

Food Sources of Lactobacillus Acidophilus

L. acidophilus is not widely found in foods, but some products are fortified with the probiotic strain.

Food products that may be fortified with L. acidophilus include:

  • Yogurt
  • Fermented milk (acidophilus milk)
  • Feta cheese

Not all brands of these foods will contain L. acidophilus, so be sure to check the ingredient list on the nutrition label to see what is included.

L. acidophilus may be present in additional fermented foods, like kimchi, kombucha, sauerkraut, and sourdough bread.

Lactobacillus Acidophilus Supplements

L. acidophilus supplements are sold in various forms, including capsules, chewable tablets, beverages, powders, and suppositories.

L. acidophilus is sometimes combined with other probiotics and nutrients to make supplements. These products are available at health-food stores, supermarkets, drugstores, and online.

There is a variety of L. acidophilus formulations. Because of this, you may benefit from reading labels and looking for two things in particular:

  • Strains: Some L. acidophilus products contain a single strain of the bacteria, while others contain several different strains or species. There are many different strains of probiotics that have similar health benefits as L. acidophilus. Look for a broad-spectrum option that includes L. acidophilus.
  • Pectin: Some L. acidophilus supplements contain pectin, a soluble fiber found in citrus and other fruits. Proponents claim that pectin is a prebiotic (a substance that promotes the growth of "good" bacteria in the gut).

Some probiotic supplements may contain milk allergens or traces of lactose. If you are allergic to milk proteins or are lactose intolerant, or if this is of concern because you are vegan, look for a supplement that is labeled as "dairy-free."

Unlike prescription and over-the-counter drugs, the FDA doesn't regulate probiotics or test them for safety. To ensure you get a quality product, look for a trusted, independent, third-party seal on the label, such as U.S. Pharmacopeia, NSF International, or ConsumerLab. This can at least give you peace of mind that what is on the product label is what is in the product itself.


L. acidophilus is a probiotic ("good" bacteria) that may be beneficial for gut health, vaginal health, and immune health. Although, some research results on these and other uses are mixed. It is naturally found in some foods but can also be used in supplement form.

If you're considering taking L. acidophilus for any condition, please consult your healthcare provider to confirm if it's appropriate and safe for you.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Brittany Lubeck, RD
Brittany Lubeck, RD, is a nutrition writer and registered dietitian with a master's degree in clinical nutrition. 

Originally written by Cathy Wong
Cathy Wong

Cathy Wong is a nutritionist and wellness expert. Her work is regularly featured in media such as First For Women, Woman's World, and Natural Health.

Learn about our editorial process