How Long Does Half-and-Half Last?

An unopened carton generally holds close to its printed date, while an opened one is best used within about 7-10 days, since exposure to air after opening speeds up the same bacterial growth that eventually sours any dairy product. A sour smell, visible curdling, or small lumps floating in what should be a smooth liquid are the clear signs a carton has turned, distinct from the harmless curdling half-and-half can show when poured into very hot or acidic coffee, which is a heat-and-acid reaction rather than spoilage.

Because that curdling reaction can happen to a perfectly fresh carton under the wrong conditions — an extra-hot cup of coffee, or coffee with unusually high acidity — it's worth checking the carton on its own, tasted plain or poured into a lukewarm cup first, before assuming a curdled cup means the half-and-half itself has spoiled. Storing it toward the back of the fridge rather than the door, and resealing the carton tightly between uses, both meaningfully extend that shorter opened window. Because half-and-half is used in fairly small amounts by most households, buying the smallest carton that covers a week or two of coffee is a practical way to avoid a half-full carton quietly souring before it's finished. A carton that's simply thinner and more watery than usual, without any sour smell, is often just a sign it's near the very end of its usable window and about to turn rather than already spoiled — a good moment to use it up in a cooked recipe rather than pour it straight into coffee.

See Half-and-Half's full storage & shelf-life guide (with spoilage signs) →