What Happens When Probiotics Expire?

Overview

• Expiration dates on probiotic bottles provide a useful guideline, but they’re not always exact. A probiotic’s potency depends on factors like strain type, the delivery vehicle, packaging, and storage conditions, all of which influence its shelf life.
• Certain probiotic species and strains, like B. animalis subsp. lactis and L. rhamnosus GG, are more resistant to environmental stresses, helping them stay viable longer.
• The packaging of your probiotics can determine how long they last. Glass and metal containers offer more protection against heat, moisture, and oxygen compared to plastic.
• For probiotics to remain effective, store them properly. Keep them in a cool, dry place and follow storage instructions to ensure they stay potent through their expiry date.
• DIY tests like the “milk test” aren’t reliable for checking probiotic viability.

You finally remember to take your probiotics—only to notice the expiration date passed weeks ago. Do they still work, or are you just swallowing expensive dust?

Probiotic organisms are microscopic and placed in a hibernated dried state that need to survive until consumption to be effective. Their lifespan depends on more than just a label with a date on it, including the bacterial strains used, the delivery vehicle, packaging, and storage conditions.^1,2 

Then what’s the point of the expiration date on the bottle? Great question! 

When a probiotic is tested and shown to be effective in clinical studies, it’s important that the product contains the same amount of live bacteria when you buy it—typically at least one billion. Over time, factors like heat and moisture can reduce the number of live bacteria, which is where the expiration date comes in.^1,3

Basically, companies add expiry labels to let consumers know how long their product will provide the intended, clinically tested dose. 

Why Probiotic Expiration Dates Matter

The widely accepted scientific definition of probiotics came from the World Health Organization, which states that “probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host,”⁴ In other words, if too many of them die off before they make it to your gut, they won’t be able to do what they’re meant to.³  

Pro tip: To ensure you’re getting probiotics that maintain their potency, consider choosing products with advanced delivery technologies, like Seed’s DS-01® Daily Synbiotic. Its ViaCap® technology is designed to protect probiotics as they travel through your digestive system, helping them reach your gut alive and effective.

What Affects Probiotic Shelf Life? 

Several factors play into how long probiotics last, from the strains used in the ingredients to how the product is packaged before it’s shipped. Here’s a closer look at the key elements that influence probiotic longevity:

• Strain resilience: Not all probiotic strains are created equal! Some species and strains last longer because of what they can tolerate. Bifidobacterium animalis subsp. lactis and Lactobacillus rhamnosus GG, for instance, are resilient to various forms of environmental and manufacturing stress, which directly impacts their survival over time.^5,6,7 
• Formula Design: Probiotics that are paired with prebiotics (nutrients that support the growth of beneficial bacteria, including probiotics) are known as synbiotics, and certain combinations can help the probiotics remain stable during storage.^1,8  
• Packaging: Probiotic organisms are sensitive to heat, moisture, and oxygen—all of which can damage or reduce their effectiveness.² To help preserve their potency, some brands use advanced delivery systems (for example, certain capsule types) and packaging. Viability tests show that glass and metal packaging have a more protective effect on probiotic survival than plastic packaging.³  
• Capsule Design: The way probiotics are encapsulated makes all the difference in how well they survive during storage and on the journey through your digestive system.^9,10 The capsule can act as a protective barrier, helping the probiotics make it past stomach acids and bile salts to reach the small intestine and colon, where their real work begins. Without a strong capsule (for example, one that has a precision-release system to deliver strains to the lower small intestine to support systemic benefits, including digestive, heart, skin, and gut health,) the microbes could be destroyed before ever reaching their destination.

How to Tell If Your Probiotic Has Expired

While labels with “best by” dates are helpful, they’re not the only factor to consider. Here are a few other ways to determine if your probiotics have lost their oomph:

• Storage Conditions: Probiotics need to be stored in a cool, dark, and dry place.³ Heat, humidity, and direct sunlight can accelerate their degradation.^2,3 If you’ve been storing your probiotics improperly (like in a hot car, on a window sill, or in a humid bathroom), you may have unknowingly decreased the amount of live bacteria in your probiotics, especially if they’re stored in a plastic container.³  
• Effectiveness: If the product has expired and you notice a decline in the positive effects you typically experience from taking probiotics, it might be a sign that the probiotics are no longer at the appropriate viable count.¹¹ 
• Physical Changes: Look for changes in the product itself. If the capsules appear clumped together, have an unusual smell, or are damaged in any way, this could indicate that moisture or other environmental factors have compromised the probiotics.

Do At-Home Potency Tests Work?

You may have heard of people trying a DIY method—the “milk test”—to see if their probiotics are still good. This at-home test involves mixing the probiotics-in-question with warm milk and waiting to see if it curdles. The belief is that if the milk clumps up within 24-48 hours, then it must mean that the probiotics are alive and active due to the fermentation.

However, milk tests have been debunked as a reliable way to check if your probiotics are still good to use. While this test might reveal some bacterial activity, it only works for certain types of probiotics (mainly those found in yogurt), and can’t tell you how many of the probiotic bacteria are actually present.¹²  For example, Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis do not have the ability to break down the proteins in milk.⁷ So, odds are, you wouldn’t be able to detect them in a milk test, even if they’re alive and well.¹² There’s also the possibility that the milk might curdle regardless of the probiotics, which would be misleading.

The only way to truly know if your probiotics still work is through professional laboratory testing. Scientists would count exactly how many beneficial bacteria are alive (“probiotic enumeration”), likely using the gold standard for quantifying them: the “Plate Count (PC) method.”^1,13 

But, honestly, who has time and lab contacts for that?

Instead of trying home tests or shipping your possibly expired probiotics off to some testing facility, just focus on storing them properly by following the package instructions and expiration dates.³  

How to Keep Your Probiotics Fresh

While expired probiotics usually won’t make you sick, they might not provide the health benefits you’re looking for.³ So, keeping those microorganisms effective for as long as possible starts with finding a high-quality product and storing it properly. 

Here are a few science-backed tips:

1. Look for protective packaging: High-quality probiotics will use delivery vehicles (for example, special capsules) and packaging that helps shield them from heat, moisture, humidity, and oxygen.² This might include things like moisture-resistant vials or specialized capsule coatings.^9,10 
2. Choose stable strains: Some probiotic strains have been rigorously tested for their ability to remain viable throughout their shelf life.^1,2,3,5,14 For instance, most strains of Bifidobacterium animalis subsp. lactis are known for their ability to withstand certain environmental stressors, such as exposure to air.^7,14 
3. Store correctly: Probiotics should be stored in a cool, dry place (around 72°F/22°C).² Some products are designed for room-temperature stability, while others may require refrigeration. But don’t store them in the freezer (or a cold car!) Temperatures close to freezing (32°F/0°C) can cause chemical damage during freeze-thaw cycles, leading to microbial cell death.¹⁵  

Key Insights

Probiotic products do expire, but this doesn’t necessarily mean they lose their value the moment the clock strikes midnight on their expiration date. A probiotic’s effectiveness depends on several things, including the strains used, the product’s formulation, and even the bottle it comes in.^3,5 Find the right combination of stable, clinically studied strains, protective packaging, and proper storage, and the potency of your probiotics can last for an extended period.^1,3,6   

It’s important to remember that longevity is not just about survival—it’s about ensuring that the beneficial  bacteria are able to deliver their intended effects, whether that’s helping with digestion, microbiome diversity, general gut health; or even for supporting systems beyond the gut, such as your heart, liver, kidneys, lungs, and skin. 

To maximize the benefits, try to choose products that use proven, stable and robust strains, and store your bottle of probiotics in a cool, dark, and dry place.^3,6 This way, you’ll get your money’s worth and you can be confident that your probiotics will work as intended.

Frequently Asked Questions

Are Expired Probiotics Harmful?

No, taking expired probiotics will not hurt you, but they do lose their efficacy over time.³ When the contents are non-viable, they are—by definition—no longer probiotics. 

Can I Extend My Probiotic’s Shelf Life?

If you follow storage recommendations and the manufacturer has performed the appropriate tests to set up the expiration date, there is nothing else you can do to extend the shelf-life. If you don’t follow the recommendations, you may reduce the shelf-life. 

If you’re looking for specific product recommendations, DS-01®, a daily synbiotic from Seed, stays potent for 18 months unopened and six months after opening. 

How Long Do Probiotics Last?

Many probiotic brands have a shelf life between 6 months and two years, but some can last up to four years. Check the expiration date on the product for when the microbes will start to decrease in potency below the level in which they were clinically proven to work.³ 

Why Do Some Probiotics Need To Be Refrigerated?

Some products have formulations that are less stable, requiring refrigeration to slow down microbial degradation.¹¹ Other products, like Seed’s DS-01®, are designed for room-temperature stability, so you can store it out in the open without worrying about the contents “going bad.”