Do Probiotics Need Refrigerating?

Written and medically reviewed by Dr Zeeshan Afzal (MBBS), Medical Content Lead at Welzo. Last updated: 28 July 2026.

If you have ever stood in front of the fridge holding a bottle of capsules, wondering whether you are about to ruin them either way, you are asking a fair question. Do probiotics need refrigeration? For most modern supplements sold in the UK, the answer is no — freeze-dried, moisture-protected formulas are designed to sit in a cupboard. But for live liquid products, fresh fermented drinks and certain fragile strains, refrigeration is not optional, and getting it wrong can quietly cost you most of the live bacteria you paid for.

This guide explains exactly what determines whether your probiotic needs the fridge, what actually kills probiotic bacteria (it is not only heat), how to read the storage line on your label, and what to do if you have already left a bottle out. If you are still building the basics, start with our overview of gut health in the UK, then browse the full Welzo gut health range and our probiotics collection. Readers working on a broader protocol often pair a probiotic with Akkermansia muciniphila, modified citrus pectin powder, Welzo Ultra Purity Berberine or Welzo Ultra Purity TUDCA — and each of those has its own storage rules, which we cover below. It is also worth reading our guides to shelf-stable probiotics, CFU vs AFU and how to choose a probiotic alongside this article.

Table of contents

• The short answer: do probiotics need refrigeration?
• Why storage matters: probiotics are a living product
• What actually kills probiotic bacteria
• Freeze-drying: why most probiotics no longer need the fridge
• Which probiotics do need refrigerating?
• Which probiotics do not need refrigerating?
• Strain-by-strain stability at a glance
• Refrigerated vs shelf-stable probiotics: is one better?
• How to read your probiotic label for storage instructions
• Does refrigerating a shelf-stable probiotic do any harm?
• What if you left your probiotics out?
• Storage after opening
• Storing probiotics while travelling
• Probiotics in the post: UK deliveries and summer heat
• Seven common storage mistakes
• Is your fridge actually cold enough?
• Storage rules for the rest of your gut-health shelf
• When to speak to a healthcare professional
• Key takeaways
• Frequently asked questions
• References

The short answer: do probiotics need refrigeration?

Most probiotic supplements sold in the UK today do not need refrigeration. They are freeze-dried and packaged with moisture barriers so that they remain stable at normal room temperature for their full shelf life. A minority — chiefly live liquid products, fresh fermented drinks, refrigerated dairy and some high-Bifidobacterium formulas — do need cold storage, and the manufacturer will say so on the pack.

The rule that never fails: follow the storage line on your specific product's label. Industry guidance from the International Probiotics Association is explicit that stability testing should be carried out under the same conditions that appear as the storage instruction on the finished pack. In other words, when a label says "store below 25°C" or "keep refrigerated", that instruction is the condition under which the potency claim was actually verified. Deviating from it means the CFU count on the front of the bottle no longer describes what you are swallowing.

A three-question decision tree

1. Does the label say "keep refrigerated" or "store at 2–8°C"? Then refrigerate it. No exceptions, no matter how convenient the cupboard is.
2. Is it a liquid, a fermented drink, a fresh dairy product or something you bought from a chilled cabinet? Refrigerate it, and keep it cold from the shop to your kitchen.
3. Is it a dry capsule, tablet, sachet or powder with a room-temperature storage instruction? A cool, dry, dark cupboard is correct. The fridge is optional and, for some formats, marginally counterproductive.

Why storage matters: probiotics are a living product

Probiotics are defined by an international expert consensus as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. The word doing the heavy lifting is live. Unlike vitamin D or magnesium, a probiotic is not a stable chemical — it is a population of organisms that declines over time, and how quickly it declines depends almost entirely on how it was made and how it is kept.

What "live" means for a capsule in your cupboard

Freeze-dried probiotic cells are not busily metabolising inside the capsule. They are in a state of suspended animation: dehydrated, dormant, and waiting for water. That dormancy is precisely what makes room-temperature storage possible. It is also why moisture is far more dangerous than most people assume — water is the trigger that wakes the cells up in a bottle where there is nothing for them to eat.

CFU, AFU and the potency you actually swallow

Potency is usually expressed in colony-forming units (CFU), sometimes in active fluorescent units (AFU) measured by flow cytometry. Whichever unit is used, the number that matters is the one guaranteed at the end of shelf life, not at the time of manufacture. The US Office of Dietary Supplements makes this point directly: because probiotics must be alive to have an effect and they die off during shelf life, consumers should look for products labelled with CFU at the end of shelf life. The same principle appears in the FAO/WHO guidance summarised by ISAPP, which recommends labels state minimum viable numbers of each strain at the end of shelf life.

This is not a theoretical concern. In a peer-reviewed analysis of 52 commercial probiotic supplements using US Pharmacopeial methods, 17 samples — 33% — were below their label claim for CFU before their expiry dates. A more recent laboratory assessment of 28 commercial probiotic products across capsules, powders, drops, suspensions, chocolate bars and chewable tablets found that 46.43% had CFU counts lower than the labelled values. Storage is one of several reasons why. For more on interpreting potency figures, see our explainer on CFU vs AFU and our guide to high-strength probiotics.

What actually kills probiotic bacteria

Ask most people what damages a probiotic and they will say heat. Heat matters, but it is only one of five stressors — and in a sealed dry supplement, it is often not the most important one.

1. Temperature

Higher temperatures accelerate the rate at which viable cells die off. A 2020 review of storage temperature and packaging in a fermented food concluded that high temperature meaningfully decreases microbial viability, while refrigeration has been reported to be better for the survival of certain probiotics. The effect is strain-dependent, not universal — which is exactly why blanket advice fails.

2. Moisture and water activity — the biggest hidden threat

This is the one most people miss. Freeze-drying works by removing water, and dried probiotic powders remain stable only while they stay dry. Laboratory work on dried Lacticaseibacillus paracasei stored at 4°C, 25°C and 37°C found that both storage temperature and the water activity of the powder governed survival, with drier powders and colder storage preserving viability best. Researchers reviewing targeted probiotic delivery have gone as far as suggesting that even encapsulated products should be refrigerated after opening, because humid air can drive metabolic activity and degradation once the seal is broken.

Practically, this means a bottle left open on a steamy bathroom shelf can lose potency faster than the same bottle left in a warm but bone-dry cupboard.

3. Oxygen

Bifidobacterium species are anaerobes and are among the most oxygen-sensitive organisms used commercially. This is one reason blister packs, nitrogen-flushed bottles and desiccant sachets exist, and one reason a bottle that is opened and closed twice a day behaves differently from a sealed one.

4. Light

UV exposure damages microbial cells. Amber glass, opaque HDPE bottles and foil blisters are all light barriers. Storing a probiotic on a sunny windowsill undermines a design feature you already paid for.

5. Time

Even under perfect conditions, cell counts fall. This is why reputable manufacturers add a deliberate overage at production so the product still meets its stated CFU at expiry. Buying a product close to its best-before date and then storing it badly stacks two losses on top of each other.

Freeze-drying: why most probiotics no longer need the fridge

Lyophilisation, or freeze-drying, is the reason the modern probiotic aisle is not a chiller cabinet. The process freezes the bacterial culture and then removes water under vacuum, leaving a dry powder in which the cells are dormant rather than dead. Cryoprotectants — skimmed milk powder, sugars such as sucrose and trehalose, prebiotic fibres — are added to protect cell membranes through the freeze-drying step.

A widely cited 2019 review of probiotic production and delivery notes that probiotics incorporated into dietary supplements and other dry food matrices are expected to have up to 24 months of stability at ambient temperature and humidity. That is not marketing; it is the design target that shelf-stable formulations are built and stability-tested against.

Why packaging often matters more than your fridge

Once a strain is freeze-dried, the job of the packaging is to keep water and oxygen away from it. That is achieved with:

• Aluminium blister packs — each dose sealed individually, so the rest of the pack never meets room air.
• Desiccant canisters or sachets in HDPE bottles, which absorb incoming moisture.
• Nitrogen flushing to displace oxygen at fill.
• Delayed-release or acid-resistant capsules, which also help cells survive the stomach — see do probiotics survive stomach acid?

A well-packaged shelf-stable product can outperform a poorly handled refrigerated one. Conversely, a refrigerated product that was allowed to warm up in transit has already lost part of what you were buying.

Which probiotics do need refrigerating?

Live liquid probiotics and fermented drinks

In a liquid product the bacteria are not dormant — they are hydrated and metabolically active. Cold storage slows that metabolism down; room temperature lets it run, consuming the substrate and changing the product. Almost every live liquid probiotic sold in the UK carries a refrigeration instruction, at minimum after opening. Our reviews of Symprove and the best probiotic drinks in the UK cover the specific handling requirements of the main brands.

Live yoghurt, kefir and refrigerated fermented foods

These are foods first and probiotic vehicles second. They need refrigeration for straightforward food-safety reasons as well as culture viability. The Food Standards Agency advises that the fridge should be set between 0°C and 5°C and that chilled food should be kept out of it for the shortest time possible. See our guides to kefir benefits, fermented foods in the UK and kefir vs probiotic supplements.

Some high-Bifidobacterium formulations

The Council for Responsible Nutrition's retailer education white paper notes that although probiotics are usually manufactured with sufficient overages to guarantee the claimed quantity at end of shelf life when stored as directed, refrigeration at retail should be considered for products containing highly unstable strains — including most of the Bifidobacterium genus. If your product is Bifidobacterium-dominant and the label recommends refrigeration, take that seriously. Our guide to Bifidobacterium longum goes into strain-level detail.

Anything the label tells you to

Some manufacturers use fragile strain combinations, moisture-permeable packaging or a shorter shelf life, and compensate with cold storage. If refrigeration is on the pack, it is part of the specification, not a suggestion.

Which probiotics do not need refrigerating?

Spore-forming Bacillus strains

Species such as Bacillus coagulans, Bacillus subtilis and Bacillus clausii form endospores — dormant structures with dehydrated cores and protective coats that make them remarkably resistant to heat, moisture and mechanical stress. A 2024 review in Foods reported that during baking at 180°C for 20 minutes, most tested Bacillus strains showed a reduction of roughly 2 log CFU/g, a level of survival that ordinary vegetative probiotics simply cannot achieve. For a category built around this property, see spore-based probiotics, Bacillus coagulans and our comparison of spore-forming vs Lactobacillus probiotics.

Saccharomyces boulardii

This is a yeast rather than a bacterium, and freeze-dried preparations are conventionally supplied as room-temperature-stable capsules or sachets. Read more in our guide to Saccharomyces boulardii in the UK.

Freeze-dried Lactobacillus and Bifidobacterium in protective packaging

Plenty of Lactobacillus and Bifidobacterium products are perfectly stable at room temperature, provided the freeze-drying, cryoprotectant system and moisture barrier were designed together. Strains such as Lactobacillus rhamnosus GG and Lactobacillus plantarum appear in both refrigerated and shelf-stable products, which tells you the format matters as much as the species.

Strain-by-strain stability at a glance

The table below is a general guide to relative robustness. It does not override the storage instruction on your specific product, because formulation and packaging can move any strain in either direction.

Refrigerated vs shelf-stable probiotics: is one better?

Neither format is inherently superior. Refrigeration is a manufacturing decision, not a quality badge, and treating a chilled cabinet as a proxy for potency is one of the most common mistakes UK shoppers make.

Consistency beats theoretical potency. A shelf-stable product you take every morning will almost always outperform a refrigerated one you forget four days a week — a point we develop in should I take probiotics every day? and how long do probiotics take to work?

How to read your probiotic label for storage instructions

The four phrases worth finding

• "Store below 25°C in a cool, dry place" — a shelf-stable product. Cupboard is correct.
• "Keep refrigerated" or "Store at 2–8°C" — refrigerate from purchase, without exception.
• "Refrigerate after opening" — cupboard until the seal is broken, fridge thereafter.
• "CFU guaranteed through end of shelf life" — the strongest quality signal on any probiotic pack.

"At time of manufacture" is a warning sign

An asterisk explaining that the CFU figure applies at the time of manufacture tells you nothing about what is in the bottle when you open it. Trade guidance from the International Probiotics Association is that products should contain 100% of the declared quantity at end of shelf life, not at production. Where a brand will not commit to that, the headline CFU number is close to meaningless.

What the official storage terms actually mean

The United States Pharmacopeia's general chapter on packaging and storage requirements defines the vocabulary that most supplement labels borrow. These definitions are a useful reference for home storage:

Note the last row. A "dry place" has a formal definition, and a bathroom cabinet next to a shower does not meet it.

Does refrigerating a shelf-stable probiotic do any harm?

Generally, no — with one caveat

Putting a sealed, dry, shelf-stable probiotic in the fridge is unlikely to damage it, and for many freeze-dried strains a lower storage temperature slows the rate of decline. The International Probiotics Association's own consumer-facing conclusion is that if you have room in the fridge, storing them there will not hurt and may keep more organisms alive.

The condensation caveat

The risk is not the cold; it is the humidity swing. Taking a cold bottle out, opening it in a warm kitchen and letting moist air condense on the chilled powder introduces exactly the water that freeze-drying removed. If you do refrigerate a dry product:

• Keep the cap tightly closed and leave any desiccant sachet inside.
• Take out what you need quickly and return it promptly.
• Do not decant capsules into a pill organiser stored in the fridge.
• Never store a dry probiotic in the fridge door, where temperature cycling is greatest.

Never freeze a probiotic supplement

Home freezers are not laboratory freezers. Uncontrolled freezing and thawing forms ice crystals that rupture cell membranes, and repeated cycles are worse than a single one. Freezing is not a way to extend a probiotic's life.

What if you left your probiotics out?

The honest answer is that it depends on the product, the temperature and the length of exposure, and no one can give you a precise percentage without testing the batch. What you can do is judge the risk sensibly.

Low concern

A sealed, dry, shelf-stable capsule left in a cupboard, handbag or desk drawer at UK room temperature for hours or days. This is what the product was designed for.

Moderate concern

A refrigerated dry product left at room temperature overnight, or a shelf-stable product that spent a hot afternoon somewhere above 30°C. Some loss of viable cells is likely; the product is not dangerous, and the sensible response is to return it to correct storage and use it sooner rather than later.

High concern — discard

• A live liquid or fermented drink left out of the fridge beyond the label's stated window.
• Any probiotic that was left in a car, conservatory or windowsill in summer heat.
• Any product showing clumping, caking, discolouration, a swollen sachet, a damaged blister, or an off smell.
• Any refrigerated product that arrived warm in the post.

How can you tell if a probiotic has "gone off"?

You usually cannot, and that is the difficult part. Loss of viability is invisible and odourless in a dry capsule. The only reliable signals are visible moisture damage, format changes such as caking, and the absence of any effect you had previously noticed. If in doubt with a poorly stored bottle, replace it — the cost of a replacement is lower than the cost of three months of taking something inert. Our article on do probiotics actually work? covers how to judge whether a product is doing anything for you.

Storage after opening

Opening the pack is the moment the storage question genuinely changes. Every time you open a bottle you exchange the protected internal atmosphere for room air carrying moisture and oxygen.

• Close it properly and immediately. Most potency loss after opening is a humidity problem, not a temperature problem.
• Leave the desiccant in. It is not packing filler; it is an active moisture barrier.
• Keep it out of the bathroom and away from the kettle, hob and dishwasher.
• Follow "use within X days of opening" where it appears, particularly on liquids and sachets.
• Do not decant into unlabelled containers. You lose both the barrier and the expiry date.
• Blister packs are the exception — each dose stays sealed until you press it out, which is why they travel so well.

Timing your dose is a separate question with its own evidence base — see when to take probiotics and probiotics after antibiotics.

Storing probiotics while travelling

Travel is where refrigerated products fall down and where shelf-stable formats earn their place. A few practical rules:

• Choose a spore-based or blister-packed product for trips. Endospore formers are the most forgiving format in a hot climate.
• Keep supplements in hand luggage. Aircraft holds experience wide temperature swings; cabins do not.
• Never leave a bottle in a parked car. Interior temperatures easily exceed the "excessive heat" threshold of 40°C in summer.
• Use an insulated pouch with a cool pack if you must carry a refrigerated product, and treat it like a chilled food.
• Take only what you need in a small labelled container, leaving the main bottle sealed at home.

If you are travelling specifically to reduce the risk of gastrointestinal upset abroad, read our guides to travel probiotics and probiotics for traveller's diarrhoea.

Probiotics in the post: UK deliveries and summer heat

Ordering online adds a stage that most people never think about. A refrigerated product posted in an ordinary parcel is out of the cold chain from the moment it leaves the warehouse. During a UK heatwave, a package sitting in a delivery van or on a doorstep can spend hours well above 30°C.

What to look for from any online retailer:

• Clear statement of whether the product requires cold storage.
• Insulated packaging and cool packs for anything refrigerated.
• A potency guarantee that runs to the expiry date under stated storage conditions.
• Strain-level identification, not just genus and species.
• Batch number and a visible best-before date.

For most UK households, this is the strongest practical argument for choosing a well-formulated shelf-stable product: it removes an entire category of risk you cannot control. Our best probiotics UK round-up and comparison of Optibac vs Bio-Kult both account for storage format.

Seven common storage mistakes

1. The bathroom cabinet. Warm, humid, and the single worst place in a British home for any dry supplement.
2. Above the oven, kettle or dishwasher. Repeated heat and steam exposure.
3. The car glovebox. Summer interiors comfortably exceed 40°C.
4. The fridge door. The warmest, most temperature-variable part of the fridge.
5. Windowsills and conservatories. UV plus heat.
6. Throwing away the desiccant. It is doing real work.
7. Leaving the lid off while you get on with breakfast. Humid kitchen air is the enemy of dry powder.

Is your fridge actually cold enough?

If you are relying on refrigeration to protect a live product, it is worth knowing that a lot of British fridges are not running where their owners think they are. The Food Standards Agency advises a fridge temperature of 0–5°C. In the FSA's Kitchen Life 2 study, 65 households had fridge thermometers installed during fieldwork; in 34 of them, the average fridge temperature was above the recommended maximum of 5°C, and 8 households averaged above 8°C. The project's literature review cited a UK study in which fridge temperatures ranged from −1.72°C to nearly 18°C, with no fridge staying within the correct operating range throughout, and only 5% within guidelines for 80% of the study period.

Two practical implications. First, if your probiotic needs refrigeration, buy a cheap fridge thermometer and check it — the built-in dial is a power setting, not a temperature reading. Second, if your fridge is unreliable, a well-formulated shelf-stable product may genuinely be the safer choice for you.

Storage rules for the rest of your gut-health shelf

Storage advice for probiotics does not transfer to everything else in the cupboard, and the differences are worth knowing:

• Prebiotic fibres and powders (inulin, psyllium, partially hydrolysed guar gum) are not alive. They need dryness rather than cold, and they clump badly if they take on moisture. See best prebiotic supplements and prebiotic vs probiotic.
• Synbiotics contain live organisms and follow probiotic rules — see synbiotic supplements.
• Pasteurised Akkermansia muciniphila is a heat-treated postbiotic rather than a live culture, which changes the stability picture entirely. Read pasteurised Akkermansia explained and Akkermansia vs conventional probiotics, and see the Welzo Akkermansia product page for its specific storage instruction.
• Botanical and bile-acid supplements such as berberine and TUDCA are chemical actives, not organisms; cool, dry and dark is sufficient. Check berberine interactions and TUDCA side effects before combining them with anything else.
• Pectin powders such as modified citrus pectin are hygroscopic — keep the container sealed and the scoop dry.
• Digestive enzymes are proteins and are heat-sensitive in their own way — see how to take digestive enzymes.

If you are assembling a wider routine, our pieces on gut reset protocols, microbiome diversity and the best foods for gut health put supplements in context. Storage is a small lever; diet is a large one.

When to speak to a healthcare professional

Probiotics are generally well tolerated in healthy adults, but they are not appropriate for everyone. The NHS advises that if you have an existing health condition or a weakened immune system, you should talk to a doctor before taking any probiotic supplement. That applies regardless of how the product is stored.

Speak to your GP or pharmacist before starting, or continuing, a probiotic if you:

• Are significantly immunocompromised, including during chemotherapy or after transplantation.
• Have a central venous catheter or an indwelling line.
• Have a serious underlying illness, short bowel syndrome, or are critically unwell.
• Are pregnant or breastfeeding and unsure about a specific product — see probiotics in pregnancy.
• Are choosing a product for an infant or child — see baby probiotics and children's probiotics.

Separately, storage is never the explanation for red-flag symptoms. Seek prompt medical assessment for unexplained weight loss, blood in your stool, a persistent change in bowel habit lasting more than three weeks, difficulty swallowing, persistent vomiting, or a new abdominal mass. Our guide on when to see your GP about stomach problems sets out the thresholds, and bowel cancer screening in the UK explains the national programme.

Key takeaways

• Most modern probiotic supplements are freeze-dried and shelf-stable; they do not need refrigeration.
• Live liquids, fermented drinks, cultured dairy and some Bifidobacterium-heavy formulas do need the fridge.
• The label's storage line is the condition under which the product's potency was actually tested — follow it.
• Moisture is at least as damaging as heat. Keep the cap on, keep the desiccant in, and stay out of the bathroom.
• Refrigerating a sealed dry product is usually harmless and may help slightly; freezing is not advisable.
• "CFU at end of shelf life" is a far better quality signal than a big number "at time of manufacture".
• Refrigerated is not a synonym for better. Consistency of use matters more than storage temperature.

Frequently asked questions

Do probiotics need refrigeration?

Most do not. The majority of probiotic supplements sold in the UK are freeze-dried and packaged with moisture barriers, so they stay stable at room temperature for their full shelf life. Live liquid probiotics, fermented drinks, cultured dairy and certain fragile strain blends do require refrigeration, and their labels will say so. The storage instruction on your specific product is the one that counts, because that is the condition under which its potency was verified.

What happens if you don't refrigerate probiotics that say "keep refrigerated"?

Viable cell counts fall faster than the manufacturer's stability data assumes, so you may be taking fewer live organisms than the label claims. It is a potency problem rather than a safety problem for dry products. For live liquids and fermented dairy, leaving them out is also a food-safety issue, and they should be discarded if left beyond the stated window.

Are refrigerated probiotics better than shelf-stable ones?

No. Refrigeration reflects the strains and formulation a manufacturer chose, not the quality of the product. A well-designed shelf-stable formula with a guaranteed CFU count at expiry can deliver more live organisms to your gut than a refrigerated product whose cold chain was broken in transit. Judge products on strain identification, dose, evidence and an end-of-shelf-life potency guarantee.

Can you put shelf-stable probiotics in the fridge anyway?

Yes, in most cases, and for many freeze-dried strains the cooler temperature slows the natural decline in viable cells. The one thing to avoid is condensation: keep the cap tightly sealed, leave the desiccant inside, take your dose quickly and put the bottle back. Do not store it in the fridge door.

Can probiotics be frozen?

Freezing is not recommended for consumer probiotic supplements. Domestic freezers cycle in temperature, and uncontrolled freezing and thawing can form ice crystals that damage bacterial cell membranes. Commercial freeze-drying is a precisely controlled industrial process and is not comparable to putting a bottle in your freezer.

How long can probiotics stay out of the fridge?

There is no single number, because it depends on the strain, the format and the temperature. Sealed dry capsules designed for room temperature are unaffected by ordinary cupboard conditions. A refrigerated dry product left out overnight will likely lose some viability but is not unsafe. A live liquid or fermented product left out beyond its stated window should be discarded. If a product spent time above 30°C, treat its potency as reduced.

Do probiotic gummies, powders and sachets need refrigerating?

Usually not, but they are more vulnerable to humidity than capsules. Gummies contain moisture by design and are typically formulated with robust spore-forming strains for that reason. Powders and sachets should be kept sealed and dry, and single-dose sachets should be used immediately once opened. Always check the pack.

Does refrigeration make probiotics last past their expiry date?

No. The expiry or best-before date is the manufacturer's guarantee of the stated CFU count when the product is stored as directed. Refrigerating it does not extend that guarantee, and there is no reliable way to know what remains viable after the date has passed. Replace the product rather than trying to stretch it.

Should I refrigerate my probiotic after opening it?

Only if the label says so. Some manufacturers specify "refrigerate after opening" because the sealed pack, not the fridge, was doing the protective work. Where no such instruction appears, a cool, dry, dark cupboard with the cap tightly closed is appropriate. Researchers reviewing probiotic delivery have suggested refrigeration after opening as an extra safeguard against humidity, so it is a reasonable precaution if you live somewhere damp.

How do I know if my probiotic is still alive?

Without laboratory testing, you cannot know for certain, which is why storage discipline matters. Practical indicators of a problem include clumping or caking of powder, discolouration, a damaged blister or swollen sachet, an unusual smell, or a product that arrived warm when it should have been chilled. The best protection is buying from a retailer that guarantees potency to the expiry date under stated storage conditions, and then storing it exactly as instructed.

References

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2. National Institutes of Health, Office of Dietary Supplements. Probiotics: Fact Sheet for Health Professionals.
3. International Probiotics Association. Probiotic Supplements: Refrigerate or Not?
4. International Probiotics Association. 5 Essentials for a Quality Probiotic Label.
5. International Scientific Association for Probiotics and Prebiotics. Decoding a Probiotic Product Label.
6. United States Pharmacopeia. General Chapter <659> Packaging and Storage Requirements.
7. Council for Responsible Nutrition. Probiotics Retailer Education White Paper, 2021.
8. Fenster K, Freeburg B, Hollard C, et al. The Production and Delivery of Probiotics: A Review of a Practical Approach. Microorganisms, 2019.
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10. Cabello-Olmo M, Oneca M, Torre P, et al. Influence of Storage Temperature and Packaging on Bacteria and Yeast Viability in a Plant-Based Fermented Food. Foods, 2020.
11. Vaz de Arruda Silveira L, et al. Effect of Fluidized Bed Drying, Matrix Constituents and Structure on the Viability of Probiotic Lactobacillus paracasei ATCC 55544 during Storage at 4 °C, 25 °C and 37 °C. Microorganisms, 2022.
12. Morovic W, Hibberd AA, Zabel B, et al. Genotyping by PCR and High-Throughput Sequencing of Commercial Probiotic Products Reveals Composition Biases. Frontiers in Microbiology, 2016.
13. Label accuracy of commercial probiotics — CFU enumeration and microbial composition. Annals of Microbiology, 2026.
14. Soares MB, Almada CN, Pereira EPR, et al. The Potential of Bacillus Species as Probiotics in the Food Industry: A Review. Foods, 2024.
15. Food Standards Agency. How to chill, freeze and defrost food safely.
16. Food Standards Agency. Kitchen Life 2 research programme, including the report Storing chilled foods at incorrect temperatures, 2023.
17. NHS. Probiotics.
18. Guts UK Charity. Prebiotics and Probiotics.
19. World Gastroenterology Organisation. Global Guidelines: Probiotics and Prebiotics, 2017.

About the author

Dr Zeeshan Afzal (MBBS) is a practising doctor and the Medical Content Lead at Welzo, where he writes and reviews evidence-based content on digestive health, supplementation and preventive medicine. This article was researched against peer-reviewed literature, trade body stability guidance and UK regulatory sources, and is reviewed periodically to reflect current evidence.

Medical disclaimer

This article is intended for general information and education. It is not a substitute for individual medical advice, diagnosis or treatment. Probiotic supplements are regulated in the UK as food supplements rather than medicines, and they should not be used to treat, cure or prevent disease. Speak to your GP, pharmacist or a registered dietitian before starting a new supplement, particularly if you are pregnant or breastfeeding, immunocompromised, taking prescription medication, or managing a diagnosed gastrointestinal condition. If you have red-flag symptoms such as unexplained weight loss, rectal bleeding or a persistent change in bowel habit, seek medical assessment promptly rather than self-treating.