A Pharmacist’s Guide to Choosing the Right Probiotic

Dr. Selena Colarossi, RPh, PharmD, BASc

Written by: Dr. Selena Colarossi, RPh, PharmD, BASc

Updated: April 9th, 2024

Has a healthcare professional, friend, or even your own curiosity inspired you to start taking probiotics? Have you visited the probiotic section of your local drugstore and have no clue which product to select? If your answer to both these questions was a resounding yes – worry not! 

Like you, many Canadians find that selecting the right probiotic can be a very confusing process, and are sometimes unsure if they even need to take one at all. We are here to help, and hopefully answer some of your most burning questions below! 

What are Probiotics?

The World Health Organization (WHO) defines probiotics as “live microorganisms which when administered in adequate amounts, confer a health benefit on the host”1. The human gut contains several different types of bacteria, which are collectively referred to as your “gut microbiome” or “intestinal flora”2. Normally, you have a balance of good bacteria and bad bacteria, but sometimes factors like medications or diseases can destroy this balance. Imbalanced gut bacteria can be associated with inflammatory bowel disease (IBD), antibiotic-associated diarrhea, colon cancer, and many other diseases2Probiotics are used to replenish the good bacteria in the gut and restore the balance, which can help to improve symptoms. They can either be in supplement form (pill or powder form), or in certain fermented foods including fermented milks like some yogurt, kefir, and cheeses3

Selecting a Probiotic

There is a common misconception that taking any product labelled “probiotic” will help improve your condition or even your overall wellness. However, as with any medication, you do need to select the right probiotic product, for the right reason to reap its benefits. Here are some other key facts:

The first and most important step in determining what the right probiotic to take is, is to ask yourself what you are taking it for, and then find the correct probiotic strain, if any, that has been studied for use to improve your symptoms.


Probiotics may contain a variety of microorganisms that can be either bacteria or yeasts. Most commonly they contain bacteria that belong to groups called Lactobacillus and Bifidobacterium, or yeasts that belong to a group called Saccharomyces5. Different types of organisms have different effects, and some have multiple uses. 

We like to refer to specific organisms as strains. Each strain will have the group (or genus) name, followed by the species name, followed by the strain name. For example, Culturelle Probiotics (a CDHF Certified product) contain Lactobacillus rhamnosus GG (LGG)6. The group is Lactobacillus, the species is L. rhamnosus, and the strain is GG. Make sure to look at the strain name in its entirety when selecting the right probiotic for you, otherwise you may mix up strains that all fall under one group.

Let’s go through a few common uses of probiotics to see how the strains can differ:

Antibiotic-Associated Diarrhea

One question we get often at the pharmacy is “which probiotic should I take with my antibiotic?” Antibiotics are designed to kill off bad bacteria during an infection, but since they can’t differentiate between bad and good bacteria, they will kill both, which leads to an imbalanced gut flora and diarrhea. Antibiotic-associated diarrhea happens in about 5-30% of patients during antibiotic therapy, and up to two months after7. Yeast strains, like Saccharomyces boulardii, work well to protect the gut during antibiotic treatments, and won’t be killed off by the antibiotics themselves7. Bacterial strains, like Culturelle’s LGG, have also proven effective in preventing antibiotic-associated diarrhea8. Other effective strains include Lactobacillus acidophilusL casei GG, L bulgaricusBifidobacterium bifidumB longumEnterococcus faecium, and Streptococcus thermophiles7.

IBD – Ulcerative Colitis 

Controlled clinical trials have shown that the strain Escherichia coli Nissle, a strain combination called VSL #3 or ‘De Simone Formulation’, are effective in treating ulcerative colitis when added to standard therapy9. Other strains will have no effect despite their usefulness in other disorders, so narrowing your search is key here.

Bloating and Gas

Many Canadians suffer from abdominal bloating, gas and discomfort, but don’t meet the criteria for other gastrointestinal diseases like Irritable Bowel Syndrome10. This may leave you with a feeling of hopelessness if you don’t receive the diagnosis you were expecting, and confusion about what medications or supplements can help you. Probiotics are useful in these cases, as they can reduce unwanted symptoms and improve your quality of life. Culturelle’s LGG strain has been proven to provide a significant reduction in symptom severity when taken for bloating, gas and overall abdominal discomfort10.


Other indications for probiotic use include irritable bowel syndrome, colic, H. pylori, functional abdominal pain, bacterial vaginosis, constipation, weight management, oral health, mood disorders, eczema, and many others. If you are interested to know which strains work best for these conditions, there’s an app for that!

The Alliance for Education on Probiotics (AEProbio) created a free app (for iPhone or Android) called Probiotic Guide Canada, to help you select the right probiotic for each use. If you feel overwhelmed by all the information surrounding probiotic strains, download this handy tool from your app store so it’s ready for when you start shopping. 

Cost & Usage

Once you’ve narrowed down your selection to products containing the correct strain, you should consider other important differences between them. Price-wise, select a product that fits in your budget, and be sure to take long-term use into consideration when doing the math. We like to check the label to see how many doses are required each day, and determine how long one package will last. 

Since probiotics are over-the-counter products they are generally not covered by your private health insurer even if your doctor writes it on your prescription. Pharmacists sometimes have coupons or samples behind the counter, so it doesn’t hurt to ask before you buy!

Nearly 23% of Canadians admit they have a problem remembering to take medications on a regular basis, especially when their care plan is complicated11. While unintentional, forgetfulness can make your probiotics ineffective if you’re not taking the appropriate amount. 

If you have a busy schedule or a hard time adapting new routines, opt for a probiotic that requires infrequent dosing, like once a day.

Most probiotics can be taken with or without food, at any time of the day. It’s still important to read and follow the label of the probiotic you select in case there are any specific instructions. Ultimately, consistency is key! Follow the dosing schedule as closely as possible – taking a probiotic at random or only when you feel discomfort won’t do enough to help restore your microbiome and improve your symptoms. If you’re taking an antibiotic at the same time, it’s always best to mention this to your pharmacist. They will let you know if you need to separate the doses from each other depending on the product you take. 


In Canada, probiotics are considered natural health products (NHPs). The manufacture, packaging, labelling and importation for sale of NHPs is regulated under the National Health Products Regulations3. It’s important to check to make sure the product label has an NPN (natural product number), which tells you that it has been approved for use in Canada. Some products may label themselves as probiotics, or probiotic-containing, and make false health claims that are not backed by evidence. 

Dosage Form

You’ll want to make sure the dosage form is convenient for you and your lifestyle. Probiotics come in many forms including capsules, liquids and powders12. If you’re someone that can’t swallow capsules easily, opt for a liquid or dissolvable powder form. If you’re often travelling or on-the-go, we recommend a capsule option that can be stored at room temperature. 

You may notice some probiotic products are sold in the refrigerated section, but this doesn’t automatically make them the superior option. Just make sure you store your probiotics exactly as recommended on the product label to maintain their viability and effectiveness, and always discard your probiotics once they expire. 

Other Ingredients

Oral medications like probiotics also contain several non-medical ingredients aside from the active strain. These can include gelatin, corn starch, lactose or wheat12. If you have dietary restrictions due to allergies, lactose-intolerance, celiac disease or other digestive conditions be sure to read each product label in detail. Some probiotics, like Culturelle Probiotics, are even advertised as gluten free and vegetarian right on the front of the box to save you time6.

If All Else Fails, Ask a Pharmacist!

As always, if you get lost or confused at any point during your probiotic shopping journey, don’t hesitate to ask a pharmacist or other qualified healthcare professional for help. We are well versed in the world of probiotics and will gladly steer you in the right direction to choosing the right probiotic for you! 


  1. Food and Agricultural Organization of the United Nations and World Health Organization. (2002). Joint FAO/WHO working group report on drafting guidelines for the evaluation of probiotics in food. Food and Agricultural Organization of the United Nations.
  2. Vyas, U. & Ranganathan, N. (2012). Probiotics, Prebiotics, and Synbiotics: Gut and Beyond. Gastroenterology Research and Practice.
  3. Health Canada. (2022). Questions and Answers on Probiotics. Canada. https://www.canada.ca/en/health-canada/services/food-nutrition/food-labelling/health-claims/questions-answers-probiotics.html
  4. National Institutes of Health. (2022). Probiotics – Fact Sheet for Health Professionals.https://ods.od.nih.gov/factsheets/Probiotics-HealthProfessional/
  5. National Center for Complementary and Integrative Health. (2019). Probiotics: What You Need To Know.National Institutes of Health. https://www.nccih.nih.gov/health/probiotics-what-you-need-to-know
  6. Culturelle Probiotics. (2017). Culturelle Digestive Health Daily Probiotic Capsuleshttps://www.culturelleprobiotic.ca/products/digestive-health/digestive-health-probiotic-capsules
  7. Barbut, F. & Meynard, J. L. (2002). Managing antibiotic associated diarrhea. British Medical Journal324(7350), 1345-1346. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1123310/
  8. Szajewska, H. & Kolodziej, M. (2015). Systematic review with meta-analysis: Lactobacillus rhamnosus GG in the prevention of antibiotic-associated diarrhea in children and adults. Alimentary Pharmacology and Therapeutics, 42(10), 1149-1147. https://pubmed.ncbi.nlm.nih.gov/26365389/
  9. Fedorak, R. N. (2010). Probiotics in the Management of Ulcerative Colitis. Gastroenterology & Hepatology, 6(11), 688-690. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3033537/
  10. Di Stefano, M., Miceli, E., Armellini, E., Missanelli, A., & Corazza, G. R. (2004). Probiotics and Functional Abdominal Bleeding. Journal of Clinical Gastroenterology, 38(2), 102-103. https://journals.lww.com/jcge/Abstract/2004/07002/Probiotics_and_Functional_Abdominal_Bloating.13.aspx
  11. HealthCare Plus. (2022). Improving Medication Adherence. https://healthcareplus.ca/blog/improving-medication-adherence/
  12. Reker, D., Blum, S. M., Steiger, C., Anger, K. E., Sommer, J. M., Fanikos, J., & Traverso, G. (2019). ‘Inactive’ ingredients in oral medications. Science Translational Medicine, 11(483), 6753. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7122736/

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