Do probiotics need to be refrigerated?

Why products differ

Probiotic products contain particular living microorganisms, such as bacteria or yeasts. Strains, formulations and packaging differ. Instructions for one product do not establish what another needs: a refrigerated food and a shelf-stable capsule are different cases. For another supplement type, see storing vitamins and minerals. For benefits and safety in vulnerable people, see the probiotics evidence guide.

A 2026 laboratory study followed one batch each of ten probiotic capsule products sold in the Czech Republic for 12 months. Samples in original packaging were kept at 22°C, 6°C or −18°C under controlled conditions. Live bacterial counts generally fell faster at 22°C, but products and bacterial groups behaved differently. Some fell below stated counts under multiple conditions.

The study measured live counts, not clinical benefit or safety. It did not establish a storage rule for other products or an opened bottle. Do not assume freezing or refrigeration suits yours: follow its label and ask the manufacturer if uncertain.15

What to look for on the label

Check storage conditions, expiry or use-by date and any after-opening instructions. A label may identify the genus, species and strain. It may also list colony-forming units (CFU), an estimate of live microorganisms. Counts can fall over time, so a count at manufacture does not necessarily describe the count at expiry.1

What a study of expired products found

A 2020 laboratory study examined 33 selected expired probiotic products, most stored according to manufacturer instructions. They were between one and 22 years past their labelled dates. Researchers found living microorganisms in 22, but only five had counts at or above their original label claims.

Packaging, storage history and time since expiry differed. The study did not test whether anyone benefited from or was harmed by taking them. A surviving count does not establish safety, an effective amount or an extended expiry date for your bottle. Follow your product’s date and storage instructions; ask the manufacturer or pharmacist if uncertain.4

If it has got warm or been left in a car

Record the product name, conditions, how long the exposure lasted and whether the pack was open. Contact the manufacturer or a pharmacist. A general article cannot tell you how many organisms remain alive or whether your product still meets its label. Putting it back in the fridge does not prove the original live count is restored.1

Travelling with a probiotic

Check the label before leaving. If the product needs refrigeration, ask the manufacturer about your journey and any interruption to the stated conditions. A cooling pack alone does not prove the product stayed in range. Food and supplement import rules may also apply at your destination or transit point.1

A higher count is not the whole story

A larger CFU count alone does not prove greater benefit. The strain and the question studied matter too. People who are seriously ill or have weakened immune systems may need a health professional’s advice before using probiotics.

Some neonatal units use or study particular probiotics to help prevent serious bowel disease in premature infants, but evidence and recommendations vary. The US FDA warns that live probiotic organisms have caused serious, potentially fatal infections in hospitalised preterm infants. Decisions about a premature infant’s care belong with the neonatal team. Storage conditions alone cannot establish that a probiotic is appropriate or safe.123