Does oat milk go bad after opening?

Oat milk has become an increasingly popular plant-based milk alternative in recent years. Made from soaked and blended oats, oat milk has a creamy, mild flavor that makes it perfect for drinking, baking, and adding to coffee and cereal. But there is some confusion around how long opened oat milk lasts before it goes bad.

How long does unopened oat milk last?

An unopened carton or bottle of oat milk will typically last 5-10 days past the “best by” date printed on the package. The shelf life depends on the type of oat milk and how it was processed and packaged. Higher fat oat milks like barista blends will generally last a bit less time than low fat versions. Unopened shelf-stable oat milk in aseptic packaging can last 6-12 months at room temperature before expiring.

Does opened oat milk need to be refrigerated?

Once opened, oat milk does need to be stored in the refrigerator to prevent it from spoiling. Leaving opened oat milk at room temperature allows bacteria to multiply rapidly, causing the milk to curdle and take on a sour odor and taste.

How long is oat milk good for after opening?

The shelf life of opened oat milk depends on the type:

  • Refrigerated oat milk: lasts for 7-10 days after opening
  • Shelf-stable oat milk: lasts for 5-7 days after opening
  • Oat milk “barista blends”: last for 5-7 days after opening

These timeframes assume the oat milk is properly stored in a sealed container in the refrigerator at 40°F or below. The cooler the temperature, the better it will retain freshness.

How to tell if opened oat milk has gone bad

Here are some signs that your opened oat milk has spoiled and should be discarded:

  • Sour smell
  • Curdled texture or watery appearance
  • Mold visible on the surface
  • Expired “use by” date printed on package

If your oat milk develops an off odor, flavor, or appearance, it is best to play it safe and throw it out. Consuming spoiled milk can cause unpleasant digestive symptoms or food poisoning.

Does oat milk last longer than dairy milk?

Oat milk generally has a longer shelf life than dairy milk because it does not contain lactose sugars that can ferment and spoil as quickly. The shelf life also depends on processing methods. Here is how they compare:

Milk Type Unopened After Opening
Dairy milk 5-7 days 5-7 days
Oat milk 7-10 days 7-10 days

As you can see, both opened and unopened oat milk lasts around 2-3 days longer on average than regular dairy milk.

Tips to extend the life of opened oat milk

Here are some tips to help your oat milk stay fresh for as long as possible after opening:

  • Store in a tightly sealed container in the refrigerator immediately after use.
  • Check the “use by” date and follow it.
  • Give the carton a sniff to check for sour odors every couple days.
  • Use clean utensils to remove oat milk from the container.
  • Keep refrigerated at 40°F or below.
  • Don’t leave the container out on the counter between uses.
  • Don’t return unused milk back to the container after pouring.
  • Freeze in airtight containers to prolong shelf life for 1-2 months.

Can you freeze oat milk?

Freezing is an effective way to extend the shelf life of oat milk. To freeze:

  • Pour milk into freezer-safe containers, leaving 1⁄2 inch of headspace.
  • Seal tightly and label with date.
  • Freeze for up to 2 months.
  • Thaw in the refrigerator before using.
  • Use thawed within 1 week.
  • Avoid freezing more than once.

Freezing can cause some separation, so shake well before using thawed oat milk. The taste and nutrition should remain the same.

Uses for oat milk past its prime

If your oat milk is getting close to the end of its shelf life or has separated, don’t pour it down the drain! Here are some uses for oat milk that has overstayed its welcome:

  • Smoothies or protein shakes
  • Overnight oats
  • Chia pudding
  • Pancake or waffle batter
  • Oatmeal
  • Casseroles
  • Soups
  • Sauces or gravies
  • Baked goods like muffins, breads, cookies

The small amounts used in cooking or baking help mask separation or off flavors.

Should you smell or taste test oat milk before using?

It’s always a good idea to inspect and smell oat milk before consuming it or adding it to recipes, especially if it is near or past its printed expiration date. Look for:

  • Clumps or curdling: This indicates spoilage.
  • Sliminess: Milk that is excessively ropy or slimy is probably spoiled.
  • Off odors: Milk should smell mild and pleasant. A sour or unpleasant smell means it has gone bad.
  • Change in color: Significant darkening is a sign of spoilage.

If anything seems off, do a small taste test. Sour, bitter, or unpleasant flavors are huge red flags. When in doubt, throw it out.


The shelf life of opened oat milk is about 7-10 days when properly stored in a sealed container in the fridge. Signs that oat milk has gone bad include curdling, off smells, sliminess, and separation. To maximize freshness, keep oat milk refrigerated at all times and check expiration dates. Smell and inspect cartons before use and toss at the first signs of spoilage. Freezing can prolong the shelf life for 1-2 months. With proper storage and handling, opened oat milk can stay fresh and delicious for up to 2 weeks.

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