General Information

Acidophilus is a type of bacteria belonging to the Lactobacilli family. Lactobacilli bacteria are found throughout the human body, mainly in the digestive and genitourinary tracts. They can also be found in fermented foods such as yogurt and milk.

Common Name(s)

acidophilus, acidophilus lactobacillus, L. acidophilus

Scientific Name(s)

Lactobacillus acidophilus

Scientific Name(s)

Lactobacillus acidophilus can be taken orallyorallyto be taken by mouth (swallowed) (by mouth) as tablets, capsules, powders, or liquids. It is also available as suppositories. It can also be found in foods such as yogurt that contain this specific type of lactobacillus.

For oral formulations, a dose between 1 and 10 billion live lactobacillus acidophilus bacteria taken daily in divided doses is sufficient for most people.

Your health care provider may have recommended using this product in other ways. Contact a health care provider if you have questions.

What is this product used for?

Acidophilus is considered a probiotic, a word used to describe live bacteria that have health benefits for people who take them in adequate amounts. Probiotics help form part of the healthy, "good" digestive bacteria found naturally in the body. When taken orallyorallyto be taken by mouth (swallowed), it may help with digestion and protect against some harmful bacteria that can cause diarrhea.

Acidophilus has been used for a variety of problems including:

  • bacterial vaginosis
  • lactose intolerance
  • inflammatory bowel disease (Crohn's disease, ulcerative colitis)
  • irritable bowel syndrome
  • preventing and treating diarrhea caused by infection or antibiotics
  • vaginal infections caused by bacteria or yeast

Your health care provider may have recommended this product for other conditions. Contact a health care provider if you have questions.

What else should I be aware of?

Numerous studies have shown that acidophilus can be effective in treating vaginal infections caused by bacteria. More research is needed to determine its effectiveness in treating vaginal infections caused by yeast.

Lactobacillus acidophilus has not been shown to be effective in preventing or treating diarrhea in travellers or in people taking antibiotics, and more research still needs to be done before a firm conclusion can be made. However, Lactobacillus GG, a different type of lactobacillus, may be useful in reducing the number of days a person has severe diarrhea.

Acidophilus has not been shown to improve symptoms related to lactose intolerance, inflammatory bowel disease, or irritable bowel syndrome. People who have intestinal damage or who have recently had bowel surgery should also avoid taking lactobacilli.

Acidophilus is usually well tolerated by adults. The most common side effects of oral supplements are intestinal gas and bloating. People who are lactose sensitive or intolerant may develop abdominalabdominalrelating to the stomach and intestines discomfort when taking dairy sources of acidophilus.

Lactobacilli are bacteria that can cause an infection in people with a weakened immune system, such as people with HIV/AIDS or cancer, as well as people who are taking medications that suppress the immune system or who are receiving chemotherapy. If any of these apply to you, talk to your health care professional first before taking any type of acidophilus supplements.

Women who are pregnant or breast-feeding should discuss the use of acidophilus supplements, other than that found in yogurt, with their health care professional.

If symptoms of digestive upset occur, worsen, or persist for more than 3 days, you should discontinue the use of acidophilus and consult a health care professional.

Acidophilus should not be taken at the same time as antibiotics – they should be taken at least 2 hours apart.

There may be an interaction between lactobacillus acidophilus and any of the following. If you are taking any of these, talk to your doctor before taking any acidophilus supplements.

  • alcohol
  • antibiotics
  • azathioprine
  • birth control pills and contraceptive vaginal rings
  • benzodiazepines (e.g., diazepam, lorazepam)
  • cyclosporine
  • other probiotics (e.g., lactobacillus casei, saccharomyces boulardii)
  • prednisone
  • sulfasalazine
  • sirolimus
  • tacrolimus

Before taking any new medications, including natural health products, speak to your physician, pharmacist, or other health care provider. Tell your health care provider about any natural health product you may be taking.


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  2. Acidophilus. Ulbricht C, Basch EM. Natural Standard Herb & Supplement Reference: Evidence-based Clinical Reviews. Massachusetts: Elsevier Mosby, 2005.
  3. Health Canada. Drugs and Health Products. Acidophilus product information., accessed 14 april 2009.
  4. Health Canada. Natural Health Products Compendium of Drug Monographs. Probiotics., accessed 29 June 2012.
  5. Natural Standard.Lactobacillus acidophilus. Available online via subscription. Accessed 29 June 2012.

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