What happens to probiotics if they get hot?

January 3, 2026 •

4 min read

According to research, many probiotic strains are sensitive to heat and begin to die off at temperatures above 115–120°F (46–49°C). This means that if you're wondering what happens to probiotics if they get hot, the simple answer is that the live, beneficial bacteria may be inactivated or killed, reducing the product's intended potency. However, the story doesn't end there, as new research reveals that some benefits may still remain even after heat exposure.

Quick Summary

Exposure to heat can kill live probiotic bacteria, reducing a product's potency. Some strains are more heat-resistant, and innovative packaging can offer protection. Heat-killed probiotics, also known as postbiotics, may still offer some health benefits by supporting the immune system and gut barrier.

Key Points

Heat Kills Live Probiotics: Most probiotic bacteria are sensitive to high temperatures, with many strains dying off at or above 120°F (49°C), significantly reducing the product's live culture count.
Not All Strains Are Equal: Some probiotic strains, like soil-based organisms (Bacillus), are more resilient to heat and don't require refrigeration, while others, such as Bifidobacterium, are more fragile.
Postbiotics Offer Residual Benefits: Even if killed by heat, the cellular components and metabolites left behind (called postbiotics) can still provide benefits, such as supporting immune function and strengthening the gut barrier.
Follow Storage Instructions: Always check the product label for specific storage requirements. Refrigerated probiotics must be kept cold, while shelf-stable ones should be stored in a cool, dry place away from direct heat and sunlight.
Incorporate into Cool Foods: To preserve the live bacteria in fermented foods or supplements, add them to dishes that have cooled rather than boiling-hot foods or drinks.

The Biology of Probiotics and Heat

Probiotics are living microorganisms, and their effectiveness is traditionally linked to their viability—that is, the number of live cells, measured in Colony-Forming Units (CFUs), that reach your gut. Bacteria are complex living organisms with proteins and cellular structures that are vulnerable to high temperatures. Just as with other living organisms, excessive heat can cause these structures to break down in a process called denaturation, leading to cell death.

The threshold at which probiotics begin to die is generally cited as between 115°F and 120°F (46°C and 49°C), with pasteurization temperatures (above 161°F or 72°C) killing them outright. This thermal sensitivity is why many products containing live cultures, such as yogurt and kefir, require refrigeration and why you should never add live probiotic products to boiling food or drinks.

Factors Affecting Heat Sensitivity

Not all probiotics are created equal. Their vulnerability to heat can depend on several factors:

Strain Variation: Different species and strains of probiotic bacteria have different levels of heat resistance. For example, some common strains like Lactobacillus and Bifidobacterium are quite sensitive, while spore-forming bacteria from the Bacillus genus are significantly more robust.
Manufacturing Process: Freeze-drying (lyophilization) is a common method for creating shelf-stable supplements. This process puts the bacteria into a dormant, protective state, increasing their resilience to environmental stressors like heat and moisture.
Protective Packaging: Modern packaging, such as desiccant-lined bottles or moisture-proof sachets, is designed to protect delicate probiotic strains from moisture and heat during shipping and storage.
Food Matrix: The food or supplement matrix in which the probiotics are contained can also offer protection. The fats and proteins in yogurt, for instance, may provide a buffer that helps some bacteria survive slightly higher temperatures.

The Rise of Heat-Killed Probiotics (Postbiotics)

Interestingly, research has shown that the benefits of probiotics are not solely dependent on the bacteria being alive. When probiotics are killed by heat, they release cellular components and metabolites, which are now referred to as postbiotics. These postbiotics can still have a positive effect on human health, especially on immune system modulation and gut barrier support.

For vulnerable individuals, such as the critically ill or immunocompromised, heat-killed probiotics can offer a safer alternative, as they carry no risk of live bacteria translocating from the gut into the bloodstream. While not all benefits of live cultures are replicated, postbiotics can still support gut health and immune function.

Cooking and Storage Guidelines for Probiotics

To maximize the intended benefits of your probiotic products, it is crucial to handle them correctly. Follow these simple rules:

Always check the product label for specific storage instructions. Refrigerated products should be stored between 32°F and 40°F (0°C and 4°C).
For fermented foods like kimchi or sauerkraut, avoid adding them to boiling dishes. Instead, stir them into food after it has cooled.
When using probiotic supplements in powder form, mix them into cool or lukewarm beverages, not hot tea or coffee.
Store all probiotic supplements away from direct sunlight, humidity, and heat sources, such as stovetops or bathroom cabinets.

Comparison of Live vs. Heat-Killed Probiotics


Feature	Live Probiotics	Heat-Killed Probiotics (Postbiotics)
Viability	Must remain alive and active to deliver full benefits.	Inactivated by heat; benefits come from released components.
Benefits	Broad range of benefits, including gut microbiome colonization and immune support.	Focus primarily on immune system modulation and gut barrier support.
Safety	Generally safe, but some risk for immunocompromised individuals.	No risk of live bacteria translocation; often safer for vulnerable populations.
Effectiveness	Considered the traditional gold standard for maximum effect.	Can be effective, though not for all conditions; results may differ.
Storage	Often requires refrigeration; sensitive to heat and moisture.	Shelf-stable and more resilient to high temperatures.
Availability	Widely available in supplements and fermented foods.	Increasingly available in specialized products; not yet mainstream.

The Final Conclusion

The question of what happens to probiotics if they get hot is a nuanced one. While high temperatures generally kill the live bacteria, this doesn't automatically mean the product becomes useless. For refrigerated and sensitive strains, heat exposure will reduce the intended potency. For hardy, spore-forming, or shelf-stable varieties, brief exposure may be tolerated. Furthermore, the resulting postbiotic compounds may still offer health benefits, though different from those of live cultures. Ultimately, following storage instructions and using common sense—such as adding probiotics to cool foods rather than hot ones—is the best way to ensure you're getting the most out of your purchase. The best choice depends on your specific health goals and tolerance level, but advances in technology continue to improve probiotic survivability and efficacy, even under heat stress.

Frequently Asked Questions

Most probiotic bacteria are sensitive to high temperatures and begin to die at temperatures above 115–120°F (46–49°C). Higher cooking temperatures, like those used in pasteurization, will effectively kill nearly all live probiotic cultures.

If live probiotics get hot, the majority of the beneficial bacteria will die, reducing the product's potency. However, recent research shows that the heat-killed bacterial cells (postbiotics) can still offer some health benefits, particularly for immune support.

Yes, taking standard probiotics with a hot drink will kill the live bacteria. To protect the cultures, it is best to mix powdered probiotics into a cool or lukewarm beverage or to swallow capsules with a sip of cold water.

No, not all probiotic strains are equally sensitive to heat. Certain strains, like spore-forming Bacillus species, are naturally more resilient and can survive higher temperatures, making them suitable for shelf-stable supplements.

Refrigerated probiotics contain more delicate, heat-sensitive strains that must be kept cold to maintain viability. Shelf-stable probiotics are formulated with more robust strains or are freeze-dried and packaged to withstand ambient temperatures.

If a refrigerated probiotic is left out for a short time, some bacteria may die, but it is unlikely to render the product useless, especially if it was manufactured with an overage of cultures. Forgetting once is probably not a major issue, but consistently neglecting proper storage will decrease its effectiveness.

No, you should not add probiotic-rich foods like miso paste or kimchi to boiling water, as the heat will kill the live cultures. The best practice is to remove the soup from the heat and let it cool slightly before stirring in the probiotic-containing ingredient.