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Probiotic Supplements Review (Including Pet Probiotics)

See What's Really in Probiotics and Our Top Picks

Latest Update

Probiotic for Metabolic Syndrome?

Medically reviewed and edited by Tod Cooperman, M.D.

Latest Update August 24, 2026 ⓘ

Quick Summary

What did ConsumerLab's tests of probiotics show?

Four probiotic supplements could not be Approved for quality by ConsumerLab mainly because they contained lower amounts of viable probiotic cells than expected from their labels (one contained only 14 million viable cells). Twenty-five products were Approved as they contained their listed amounts of probiotics, if not more (all of which were in the billions), and were not contaminated with pathogenic organisms (see How Products Were Evaluated and What CL Found). Eight of these products were tested through ConsumerLab's voluntary Quality Certification Program.

Brands tested included Align, BioGaia, Culturelle, Dr. Mercola, Florastor, Garden of Life, GNC, Gundry MD, Jarrow Formulas, Life Extension, Microbiome Labs, Nature's Bounty, Nature's Way, NOW, Nutramax, Pendulum, Physician's Choice, Purina, Renew Life, Seed, Swanson, Trunature (Costco), USANA, Visbiome, and VSL#3.

Which are the best probiotic supplements?

Among products that were Approved for their quality in our tests, we selected six as Top Picks for some of the most common uses of probiotics for people, as well as for dogs and cats, based on whether the product contained the types and amounts of probiotic organisms that have evidence of being effective.

What are probiotics?

Probiotics are viable (living or hibernating as spores — such as B. coagulans) bacteria and/or yeasts that confer a health benefit. Probiotics are sold as capsules, tablets, powders, chewing gums, gummies, and lozenges, as well as cultured foods and beverages, such as yogurts and kefirs.

What are the health benefits of probiotics?

While healthy people typically don't need to take a probiotic, in some situations a probiotic may modestly help prevent conditions such as diarrhea from antibiotics, symptoms of respiratory infections, and (as a lozenge) dental cavities.

Certain probiotic strains may reduce gastrointestinal symptoms such as constipation, bloating, diarrhea due to conditions such as irritable bowel syndrome and infant colic, as well as slightly lower blood pressure and cholesterol (LDL and apoB) levels, improve blood sugar control, reduce symptoms of atopic dermatitis (eczema), and reduce gum disease, among other uses (see What They Do).

What's the right dose of a probiotic?

Typically, a probiotic should provide at least 1 billion cells daily — although some probiotics have been shown to work at a lower dose (100 to 500 million cells), such as those for children or used to treat conditions in the mouth. Be aware that there can be huge variation in the number of viable cells (called colony-forming units or CFUs) from product to product. Among products tested, this ranged from just tens of millions to hundreds of billions!

If using a non-enterically coated probiotic, it may be best to take it shortly before or during a meal. Be aware that, in general, probiotics will only survive in your system for a limited amount of time (see ConsumerTips).

What to watch out for on probiotic labels:

Some products label their amounts in "AFU" which is a different way of counting cells and not a generally accepted labeling practice because it doesn't necessarily reflect how many cells can form colonies. Some products also footnote their listed amounts as being as of "time of manufacturer" which means they are not promising that you'll get that amount when you buy the product. We find this practice misleading. The FDA requires that listed amounts reflect what a consumer will get.

What are prebiotics and postbiotics?

Prebiotic ingredients are sometimes added to probiotic supplements although in amounts that are typically smaller than used clinically. Prebiotics provide soluble fiber that promotes the growth of probiotic bacteria and may be beneficial for irritable bowel syndrome, constipation, blood sugar control, lowering cholesterol, and other conditions (see our Prebiotic Supplements Review). Postbiotics are also sometimes added to probiotics. Postbiotics include heat-killed probiotics as well as the byproducts of fermentation, such as butyrate, carried out by probiotic organisms. These may be beneficial for diarrhea, Crohn's disease, irritable bowel syndrome, weight loss, and preventing common colds (see All About Postbiotics). Probiotics that include prebiotics or postbiotics have, together, have been referred to a synbiotics.

Are probiotics safe?

Probiotics may temporarily increase digestive gas. If you have a milk allergy, be aware that trace amounts of milk proteins may occur in some probiotics. Probiotics may not be safe prior to abdominal surgery and should be used with caution in people who are severely ill, immunocompromised, or have feeding tubes or central lines. For more details see Concerns and Cautions.

Products tested in 2024 and 2025

+— 281 sources

In addition the results of its expert testing, ConsumerLab uses only high-quality, evidence based, information sources. These sources include peer-reviewed studies and information from agencies such as the FDA and USDA, and the National Academy of Medicine. On evolving topics, studies from pre-print journals may be sourced. All of our content is reviewed by medical doctors and doctoral-level experts in pharmacology, toxicology, and chemistry. We continually update and medically review our information to keep our content trustworthy, accurate, and reliable. The following sources are referenced in this article:

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Probiotic supplements compared in this review

Align Probiotic

BioGaia Gastrus

Culturelle Probiotics

Dr. Mercola Complete Probiotics

Florastor

Garden_of_Life_Dr_Formulated_Probiotics_Mood_plus-50_Billion-Probiotics-small.png

Garden of Life Dr. Formulated Probiotics Mood+ - 50 Billion

Garden of Life Dr. Formulated Probiotics Once Daily Women's 50 Billion

GNC Probiotic Complex

GNC Probiotic Solutions With Enzymes 25 Billion CFUs

Gundry MD Bio Complete 3

Jarrow_Formulas_Saccharomyces_Boulardii_plus_MOS-Probiotics-small.png

Jarrow Formulas Saccharomyces Boulardii + MOS

Life Extension GI With Phage Technology

Microbiome Labs Mega Sporebiotic

Nature's Bounty Probiotic 10

Nature's Way 3-in-1 Probiotic Gummy - Women's - Orange Flavored

NOW Probiotic-10 100 Billion

Nutramax Proviabe-DC - Cat & Dog

Nutramax Proviable-Forte

Pendulum Akkermansia

Pendulum Metabolic Daily

Pendulum Metabolic Daily

Physician's Choice 60 Billion Probiotic

Purina Pro Plan FortiFlora - Dog

Renew Life Women's Care Probiotic

Seed DS-01 Daily Synbiotic

Swanson Dr. Stephen Langer's Ultimate 16 Strain Probiotic With FOS

Trunature Advanced Digestive Probiotic

USANA Probiotic

Visbiome

VSL#3 Probiotic Medical Food

You must be a member to get the full test results along with ConsumerLab.com recommendations and quality ratings. You will get results for 30 probiotic supplements, including three products for pets. Twenty-one products were selected by ConsumerLab.com and nine others are included for having passed testing in its voluntary Quality Certification Program.

Which probiotic supplements and drinks failed our tests and which ones passed
CL's Top Picks among probiotic supplements by category, including probiotic supplements for treating constipation and diarrhea, preventing C. difficile infection, treating H. pylori infection, and preventing vaginal infection
Which probiotic bacteria or yeasts have been shown effective for treating or preventing specific conditions, and at what dose. These microorganisms include Lactobacillus acidophilus, Lactobacillus GG, Bifidobacterium infantis, Saccharomyces boulardii, and many others
Price comparisons of probiotics supplements

Ingredient comparisons and what to look out for on probiotic labels
What prebiotics (often included in probiotics) can and cannot do, and how to get them from supplements and foods
Tips on how to use probiotics — and store them to last longer
Concerns, cautions, and potential side effects of probiotics -- including concerns for people with milk allergies