Most foods that say “refrigerate after opening” do so in order to prevent the food from spoiling. With hot sauce, though, “refrigerate after opening” is often a means of avoiding accidentally creating a chemical weapon. Because if you’re not careful, a bottle of hot sauce can become a Scoville bomb, coating your pantry in a layer of pureed chili, or worse, coating you and your eyeballs, instead. And even if you are careful, this can happen anyway.
A lot of popular hot sauce varieties don’t actually need to be refrigerated. Vinegar-based sauces like Sriracha or Crystal are acidic enough that bacteria can’t grow, even at room temperature. Capsaicin, the compound responsible for spiciness, further inhibits bacterial growth. More than that, most commercial hot sauces without the proper vinegar content will have added preservatives ensuring that the bottle can survive unrefrigerated for several months, anyway.
But creating hot sauces isn’t always a perfect science, and even Sriracha has undergone recalls in the past for explosive reasons. In 2019, customers in Australia and New Zealand were told to return their recently purchased Sriracha after some bottles had begun to bloat and explode upon opening. Why exactly this happened is unclear, but it’s likely because of a buildup of lactic acid in the sauce that allowed it to continue to ferment.
Fermentation produces CO2, which can build up inside the bottle and cause it to bust. Most commercial hot sauces are designed to avoid further fermentation, but small-batch or DIY hot sauces run a higher risk of continuing to ferment and then exploding. Similarly, mold can more easily develop in hot sauces without preservatives when kept at room temperature. Mold produces gas, too, adding another reason why older, opened hot sauces are at a higher risk of exploding. Hypothetically, this can happen inside the fridge, too.
Whatever you do, pay attention to the label. If it says to refrigerate it, refrigerate it. If it says to consume it all within six months of opening, do that. One thing to keep in mind is that while a hot sauce may not need to be refrigerated, it will likely last years longer if it is. The shelf-life of an opened, unrefrigerated bottle of hot sauce is around six months. In the fridge, it could last two years or longer. It’s also important to clean the lids of your hot sauce bottles so they can close properly. Bottles that have been left open or have a ton of crusty sauce around the rim are more likely to produce mold.
Exactly how you should manage your hot sauces will depend on your rate of consumption. If you’re the type to eat hot sauce with at least one meal a day, you should get through a bottle fast enough for it to be just fine out on your kitchen counter — plenty of restaurants keep their hot sauces on the table. But if you really only dabble in hot sauces every now and then, it might be better to keep them in the fridge. Six months can go by a lot faster than you think, and a hot sauce explosion is really something you probably don’t want to deal with. Have you ever gotten hot sauce in your eye? What about both eyes at once, and also your nose and mouth? Doesn’t sound fun, does it?
Long story short: Don’t let your hot sauce explode in your face.