Pantry and shelf-stable reference

Does oat milk need to be refrigerated after opening?

Yes. Oatly's own answer is that a shelf-stable carton keeps about a year unopened and about five to seven days once it is opened and kept chilled.

Unopened and opened

A shelf-stable package has two different lives, and only one of them is printed on the label. These are the windows Does Oat Drink go bad?, Oatly publishes, in its own units. Where it publishes none, this page says so rather than filling the gap.

Unopened: About a year at room temperature in a shelf-stable carton
After opening: 5 to 7 days refrigerated
Where to keep it once open: Refrigerator. Refrigeration is required here, not optional.

How to use this window

The after-opening window runs from the day the package was opened, not from the date printed on it, so that date is only useful if you wrote it down. Well Stockd does not know when this package was made, bought or opened: record the opened date, follow the package directions, keep your refrigerator at 40°F or below, and use the official item listing when food safety is in question.

Primary sources and limits

The windows above are quoted from Does Oat Drink go bad?, Oatly. Storage times are guidelines: quality varies with packaging, temperature, and how the jar is handled between uses. Nothing here overrides a package instruction that says to refrigerate.