The definitive answer: Do probiotics expire if kept in the fridge?

October 11, 2025 •

5 min read

A study examining expired probiotic products found that many still contained live bacteria, but the total cell counts were often too low to be therapeutically effective. This highlights a crucial point: Do probiotics expire if kept in the fridge? The simple answer is yes, because refrigeration only slows, but does not stop, the natural degradation of these living organisms.

Quick Summary

Probiotics, being live microorganisms, have a finite lifespan and an expiration date indicating their maximum potency. Proper storage, even refrigeration, helps extend this lifespan, but doesn't prevent their eventual expiration.

Key Points

Refrigerated probiotics do expire: As living organisms, the bacteria in refrigerated probiotics will eventually die off, rendering the supplement ineffective over time, even with ideal storage.
Refrigeration slows potency loss: Keeping probiotics in the fridge slows the decline of viable CFU counts but does not stop it completely, so the expiration date is still a critical guideline.
Expiration date is the potency guarantee: The manufacturer's expiration date indicates the point up to which they guarantee the stated number of viable CFUs, assuming proper storage.
Expired probiotics are likely safe but ineffective: Consuming expired probiotics is generally not harmful, but their potency is diminished, meaning you will not get the full health benefits.
Visible signs indicate spoilage: Look for unusual changes in color, texture (like clumping), or an off-putting odor, which can signal that the probiotics have been compromised by moisture or heat.
Temperature and moisture are key enemies: Inconsistent refrigeration, such as leaving the bottle out, can introduce moisture through condensation, while exposure to heat and humidity can destroy the living bacteria.
Follow all storage instructions: Always adhere to the specific storage instructions on the product label and keep supplements in their original, sealed container to maintain potency.

The Science Behind Probiotic Expiration

Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit to the host. The efficacy of a probiotic supplement depends on the number of viable, live bacteria it contains, which is measured in colony-forming units (CFUs). As living organisms, these bacteria have a finite lifespan and naturally begin to die off from the moment they are manufactured. The expiration date printed on the product is the manufacturer's guarantee that the stated CFU count will be maintained up to that date, provided the product is stored according to instructions.

Why the Refrigerator Isn't a Time Machine

While a refrigerator's cool, dark environment is ideal for many probiotic strains, it does not halt the expiration process entirely. It primarily serves to slow down the metabolic activity of the bacteria, thus preserving more of them for a longer period compared to room temperature storage. However, the process of degradation continues, and the number of living CFUs will inevitably decrease over time. For probiotics that require refrigeration, any lapse in proper cold storage, such as leaving the bottle out for a prolonged period, can accelerate this loss of potency.

Factors Influencing Viability (Even in the Fridge)

Even with consistent refrigeration, several factors can affect a probiotic's lifespan and effectiveness:

Temperature Fluctuations: The viability of refrigerated probiotics can suffer from frequent temperature changes. Repeatedly taking a bottle out of the fridge and returning it can cause condensation and introduce moisture, which is detrimental to freeze-dried bacteria.
Moisture: Humidity is a significant enemy of probiotics, especially those that are freeze-dried and reactivated by moisture. The original, airtight packaging is designed to keep moisture out. Exposure to humid environments, such as a bathroom, can drastically reduce viability.
Oxygen Exposure: For anaerobic bacteria like Bifidobacterium, prolonged exposure to oxygen can be harmful. Opening and closing the container can expose the contents to oxygen, leading to cell death. Some advanced packaging, like Activ-Vial™ technology, helps mitigate this by absorbing moisture.
Light Exposure: Direct sunlight and UV light can also damage or kill probiotic bacteria. The opaque or amber-colored bottles used by many manufacturers are designed to offer protection.

Refrigerated vs. Shelf-Stable Probiotics: A Comparison

To understand the nuances of probiotic expiration, it's helpful to compare refrigerated and shelf-stable options. Neither is inherently superior, but their storage requirements differ based on the strains and manufacturing processes.


Feature	Refrigerated Probiotics	Shelf-Stable Probiotics
Storage Temperature	Requires consistent refrigeration (typically 32-40°F / 0-4°C).	Can be stored at room temperature, away from direct heat and light.
Bacterial Strains	Often contain more delicate strains that are sensitive to heat and moisture, like some Lactobacillus and Bifidobacterium species.	Typically contain hardier strains (e.g., soil-based organisms) or are processed using techniques like freeze-drying to make them more robust.
Packaging	Standard opaque, airtight bottles are common. Some use advanced desiccant-lined bottles to control moisture.	Designed with high-tech, moisture-resistant packaging (e.g., blister packs or special sachets).
Travel Convenience	Less convenient for travel due to the need for a consistent cold chain.	Much more convenient for travel and busy lifestyles as they do not require constant cooling.
Potency Guarantee	Should guarantee CFU count through expiration, assuming correct storage.	Guarantees CFU count through expiration, assuming correct storage.

What Happens If You Take Expired Refrigerated Probiotics?

Taking expired probiotics is unlikely to make you sick, as they don't typically harbor harmful pathogens. The primary issue is a loss of potency and, therefore, a decrease in effectiveness. The number of viable CFUs will have dropped below the concentration needed to produce the intended health benefits, such as supporting digestion or modulating the immune system. In some cases, a very small number of individuals might experience minor gastrointestinal discomfort, but this is rare and temporary. While heat-killed probiotics can still confer some benefits, this doesn't apply to a supplement that has naturally degraded over time, and it is always best to use fresh products for maximum effect.

Proper Storage for All Probiotics

To ensure you're getting the most from your probiotic investment, regardless of whether it requires refrigeration, follow these best practices:

Always read the label: Follow the manufacturer's storage instructions precisely. If it says 'refrigerate', do it.
Keep it cool and dry: Store your probiotics in a cool, dry place, away from heat, light, and humidity. Avoid keeping them in a warm, moist bathroom cabinet.
Keep it original: Don't transfer capsules to a weekly pill organizer, as the original bottle is designed to protect its contents from environmental stressors.
Use before the date: Prioritize using the product before its expiration or 'best by' date to ensure you get the full, effective dose.

How to Know if Your Probiotics are No Longer Good

While the expiration date is your most reliable indicator, other signs can suggest a supplement's quality has been compromised:

Physical Changes: Look for clumping, discoloration, or any unusual texture in the powder or capsules. This can signal that moisture has gotten into the container.
Off-Putting Odor: If the probiotics smell sour, foul, or simply 'off', it's a clear sign they have gone bad and should be discarded.
Lack of Effect: If a probiotic that was previously effective for you stops providing the same benefits, it may be a sign of reduced potency.

Conclusion: The Final Word on Refrigerated Probiotics

Ultimately, the question of whether do probiotics expire if kept in the fridge is not about safety, but about potency. Refrigeration extends the shelf life of temperature-sensitive probiotics by slowing the decay of live bacteria, but it cannot prevent it entirely. Adhering to the expiration date and following proper storage protocols is the only way to ensure you receive the full, therapeutic benefits that these supplements are intended to provide. If your refrigerated probiotics have passed their expiration date or show signs of degradation, it is best to replace them with a fresh product to support your gut health effectively.

Source

For more detailed information on probiotic viability and factors affecting it, research published by the National Institutes of Health provides valuable insight into the science behind probiotic survival, especially during storage.

Frequently Asked Questions

No, consuming expired refrigerated probiotics is unlikely to make you sick. The primary issue is a loss of potency, not contamination. The live bacteria simply die off over time, making the supplement less effective.

Their potency begins to diminish immediately after the expiration date, as the viable CFU count decreases. While some living bacteria may remain for a while, there is no way to know if enough are left for a therapeutic effect. For maximum benefit, it's best to use them before the expiration date.

If you left refrigerated probiotics out for a short period, they are likely still viable, especially if they are freeze-dried. However, if left out for many hours or in a warm place, their potency may be compromised. Check for any signs of spoilage, like discoloration or odor, before deciding whether to use them or discard them.

Neither is inherently better. Shelf-stable probiotics are made with hardier strains or protected by advanced packaging to withstand room temperature. The best choice depends on your needs, but both are effective if stored properly. What matters most is following the label's storage instructions.

Condensation introduces moisture into the container, which can damage freeze-dried probiotic bacteria. This can happen when a cold bottle is repeatedly exposed to warmer air, accelerating the degradation of the viable microorganisms inside.

No, it is not recommended. The original packaging is specifically designed to protect probiotics from light, moisture, and oxygen. Moving them to a weekly pillbox can expose them to elements that degrade their potency.

CFU stands for Colony-Forming Unit and represents the number of viable bacteria in a probiotic supplement. It decreases over time because the bacteria are living organisms with a natural lifespan. Environmental factors like heat, light, and moisture can speed up their death rate, even when refrigerated.