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How to Tell if an Onion Is Bad?

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Onions are great because they last so long. When you buy onions, you don’t have to worry as much about them spoiling. Typically, they can sit on your countertop for weeks before they start to go bad.

It takes a lot of time for an onion to spoil. Usually, a bad onion starts turning brown or black. It can also start to smell or become slimy. Finally, the onion layers will start to separate, and once all the juice is out of the onion, it will turn dry and flimsy.

three pieces of purple onion on craft paper background

Cutting into an onion moves the clock forward because you don’t have as much time to eat it compared to a whole onion sitting somewhere dark in your kitchen or the pantry. When you slice open an onion, you usually only have a few days to eat whatever you don’t cook.

Of course, no one wants to eat a rotten onion. Here are some easy ways to tell if an onion is bad and how to store onions to extend how long you can keep them in good condition.

Raw Onions vs. Cooked Onions

Whether you’re cooking a yellow onion, red onion, or white onion, all the signs of an onion going bad are similar. The main difference in how fast an onion goes bad is whether it’s cut open or still has the skin on it.

If the onion is raw, it will last much longer. A whole onion can last for weeks on a shelf or in a cabinet. When you cut it or cook it though, it will go sour much faster. Here are some signs to look for to determine whether an onion is bad.

Brown or Black Spots

Closeup of moldy spoiled onions on a white background

Sometimes brown spots start to develop on an onion that’s been sitting around for too long. If you want, you can simply cut around the brown area and use the rest of the onion, like you would with an apple or any other fruit.

However, if an onion develops several black or brown spots around the outside layers, it’s probably a good idea to toss it in the trash can.

Foul Smell

A rotten smell is another reason to throw away your onions. Often, the onion will feel soft and look slimy and start to have an unpleasant odor. A good onion will have a faint onion odor that’s not overpowering.


macro shot of a slice of onion

The texture of your onion is another sign to look for when deciding if your onion is bad. A good onion will be crisp and full of water content. When you press against the peel, it should be firm to the touch.

Likewise, when you cut through an onion, the knife should slice through without much effort. It should feel like slicing through crisp fruit.

A bad onion will feel limper. It will bend more easily and be harder to cut. There will be less water inside the layers of the onion, so you won’t get that satisfying feeling when you cut through it.

These are just a few ways to tell if an onion is bad. Next, let’s dive into how you can store them and some information on how long you can expect them to last.

Whole and sliced purple onions on a wooden chop board on a stone countertop

How Long Do Onions Last?

A regular onion will last for weeks before you cut it open. Their long shelf life is one of the reasons why grocers typically sell onions in large bags. They don’t go rotten quickly, so you don’t need to worry about buying them in large quantities as they won’t easily go bad.

When you cut an onion open however, you dramatically shorten its lifespan. A sliced onion will usually only last a few days after it’s been cut. If, for example, your recipe only calls for half an onion, you can put the other half in a sealed bag and stick it in the fridge. But you should find a way to use it the same week to prevent wasting it.

Cooked onions will last longer than a cut raw onion. However, you should only expect to keep cooked onions for only as long as the recipe lasts. For instance, caramelized onions by themselves won’t last as long as something like canned chili.

In the right recipe, a cooked onion can last forever if the food is preserved correctly.

Pile of onions with green sprouts on a dark wooden background

Can You Eat an Onion That Is Sprouting?

Sprouting onions can freak people out a bit, but you can eat them the same as any other onion. You simply cut the sprouts off and prepare the onion the same way you would any other onion.

Sprouting onions is where we get green onions, so you’re not going to get sick or anything if you eat a sprouting onion. You only need to worry about when the sprouts get too big and start separating the onion layers.

Best Ways to Store Onions

The main concern with raw onions is keeping them in a place where they won’t sprout or come in contact with anything that will spoil them. If you leave onions on the kitchen windowsill, for example, they’ll get too much sunlight and will start to sprout.

You can keep onions from sprouting by storing them in a dark place, like the bottom shelves of your pantry or inside some of your cabinets.

Don’t put raw onions in the fridge because it will mess with their internal moisture levels. Colder temperatures can dry out your onions faster than you’d like, so just keep them somewhere that’s room temperature and dry.

Can you freeze onions? Freezing onions is a better alternative to storing partially used onions in the fridge. By freezing them, you’re stopping the spoilage process. You freeze them in the state they were in when you cut them.

Thawing frozen onions takes a bit more preparation, but you can thaw them and use them for cooking without any problems.

baskets with potatoes and onions on shelf in the kitchen


Thankfully, onions are some of the most affordable items you’ll find in your grocery store farm produce section. The main thing you want to avoid is eating any spoiled onions to avoid getting sick or ruining the dinner that you’re making. These tips will keep your onions fresh longer and help you spot any rotten onions.