How to Tell If An Onion is Bad


Do Onions Go Bad? Yes, they can. And if they do, you shouldn’t eat them. We will help you know the key indicators and how to tell if an onion is bad or spoiled.

We’ve also included bonus material for the best ways you can store onions to maximize shelf life, as well as frequently asked questions relating to onions.

yellow Onion on burlap

What To Look For When Buying Onions

Have you ever been to the grocery store to buy onions and come home only to find that one of them in the bag was rotten? It’s frustrating isn’t it. Because sometimes one bad onion in the bunch can cause the others to spoil too.

When buying onions, you want to know how long do onions stay fresh? And you’ll want to look for ones that are nice and firm, have a smooth blemish free skin, and are not yet sprouted.

Take time to look through the package of onions at each individual onion in that package before making your selection.

Key Indicators: How to Tell if An Onion is Bad [Definitive Guide]

There are key indicators that are different ways of telling if an onion has gone bad. These can be used to evaluate whether your onion should be eaten. These are the best ways to tell if an onion is bad.

By doing a careful evaluation of an onion using these factors, you will be able to have a good knowledge of knowing whether your onion is bad or whether it is safe to eat.

red onions in a basket

Signs That Onions Are Bad:

Mold. If mold has developed on the outside of your onion, it’s likely an indicator of what is happening on the inside of the onion as well. Don’t eat an onion that has mold on it.

Discolored. Sometimes onions will develop dark spots or discolored areas on their skins. This is usually a good indicator that the onion has spoiled.

Rotten odor. What does a bad onion smell like? If you’re not sure whether your onion is still good, often the sniff test will let you know. And if there’s white liquid, or any liquid for that matter, coming from the onion, then it’s bad. If the onion has a rotten garbage smell, then it has gone bad.  Please throw it away.

Soft squishy. If the onion is soft or squishy when you give it a gentle squeeze, or seems slimy, those are all indicators that the onion has spoiled. A good onion should be nice and firm.

Dry flesh. As an onion begins to spoil, sometimes its flesh will become dry and dehydrated. If you notice this, throw the onion away rather than eating it.

Sprouting. An onion that is sprouting can also be a good indicator that the onion is no longer good to eat. Spoiled onions tend to sprout before they rot away.

How to properly store onions

What is the best way to store onions? And how to store onions for a longer use? If you’ve selected healthy onions at the point of purchase and bring them home and want to maximize the onion’s shelf life, the next key will be to how they’re stored.

Here are the best recommendations for how to store onions for length of shelf life.

Keep them away from moisture

Select a dry place, that’s not humid to store your onions. This will help keep mold from developing on them and will help them to last as long as possible.

Get the temperature right

A cool place is the best place to store onions whether they’re whole or cut. Consider placing them in the crisper drawer in your refrigerator so long as they won’t risk freezing there. Or a cool, dry cellar is also ideal.

Store away from other foods

If your onion has already been cut, you’ll want to ensure that it’s been sealed in an airtight container or zipped food storage bag to keep it away from other foods in your refrigerator.

If not, you risk everything in the vicinity absorbing the flavor of the onion. It’s an important step for how to keep an onion fresh.


The best place to store onion is usually in the refrigerator. This is true for whole onions as well as cooked onions.

Use the right packaging

For cut onions, make sure they’re sealed in an airtight container or zipped food safe storage bag before moving them to the refrigerator or freezer.

Types of Onions

There are many varieties of onions that can be used in cooking and for eating. Which onion is healthiest? All onions have healthy antioxidants that can be of benefit.

Some of the more popular types of onions include Vidalia, yellow onion, green onion, brown onion, red onion, purple onion, and white onion.

barbers french onion dip caramelized onions

Shelf Life of Onions

Following is the estimated shelf life of onions if stored in a optimum storage environment.

Pantry. Whole onions stored in a cool, dry pantry can usually last 4-6 weeks.

Refrigerator. Whole onions stored in a cool, dry refrigerator can usually last for up to 3 months.

Cut. For how to store a cut onion, you can place it in an airtight container on the counter. It can last 1-2 days at room temperature, 1 week in the refrigerator, and up to 3 months in the freezer.

How to Tell if an Onion is Bad After Cooking 

You can use similar indicators to know whether an onion is bad after it’s been cooked.

If it smells strange, develops a slimy texture, becomes discolored, grows mold, or tastes off, your onion is likely no good and should be thrown away.

Frequently Asked Questions

Following are questions that are asked frequently about how to tell if an onion is bad and everything you ever wanted to know. We trust you’ll find our answers helpful. If you have questions that we don’t have listed here, please submit them in the comments box below.

spoiled onion

How long do whole onions last?

Storing an onion whole will provide the greatest shelf length of onions that are fresh. A whole onion, if kept in a cool, dry place such as the crisper drawer of your refrigerator can last for up to 6 weeks.

How to store peeled or cut onions?

If you have peeled or cut onions, the best way to store them is in an airtight container in the refrigerator.

If peeled or cut onions are not used as soon as they’re prepared, they should only be used as cooked onions, rather than consumed raw.

How long do onions last in the freezer?

Can you freeze raw onions? Yes, onions can last for up to three months in the freezer. When freezing an onion, you should prepare them as desired then place them in a zipped freezer bag, labeled with the contents and date.

How long are onions good for?

How Long Do Onions Last? How long onions are good for varies depending on the current state of onion such as whether it’s peeled, sliced, diced, or still whole with the skin on, as well as where the onion is stored.

Whole onions with the skin still on that are stored in a cool, dry place will last for about 6 weeks.

Frozen onions prepared and sealed in a zipped freezer bag will last for about 3 months.

Cut or sliced onions, stored in the refrigerator will last for up to a week, and should be used only for cooking and not eaten raw once they’re left in the refrigerator overnight.

For the greatest shelf life for fresh onions, follow our recommended storage guidelines.

Where should onions and potatoes be stored?

Onions and potatoes should be stored in a cool, dry location to lengthen their shelf life.

How to make sure onions stay fresh for longer?

The best way to make sure onions stay fresh longer is to buy fresh onions and store them properly.

How to use onion for garnishing?

The best onion to use for garnishing is the green onion or spring onion. Just wash it thoroughly and use kitchen scissors to cut the green ends of the onion.

Green onion adds a beautiful green color as well as delicious flavor to savory dishes.

Can you get sick from eating a bad onion?

Yes, you can get sick from eating a bad onion. Bad onions can store bacteria, and when consumed can make a person sick.

To avoid eating a bad onion, follow our key indicators for how to tell if an onion is bad.

What does a lousy onion smell like?

If you’re giving your onion the smell test, but you’re not sure what to look for, let us just say you’ll know a bad onion when you smell it.

A bad onion smells like rotting garbage. That’s the best way we can explain it.

How to tell if onions are bad, rotten, or spoiled?

Use your senses to know if an onion is bad, as well as our key indicators for how to tell if an onion is bad.

If an onion has mold, is discolored, has a strange odor, feels slimy, is soft, is oozing juices, do not use it, instead throw it away.

Can you eat an onion that has sprouted?

With the exception of green onions, you should know that when an onion sprouts it’s usually an indicator that the onion is spoiled.

Check the onion for other key indicators that the onion has gone bad.

How to store onions to extend their shelf life?

What’s the best way to store onions? The best way to store onions to extend their shelf life as fresh onions, is to leave them whole, with skin on and store them in a cool, dry location.

We recommend placing them in a refrigerator crisper drawer or in a cool cellar.

How to use extra before your onions go bad?

There are three main ways to use extra onions before they go bad. The first is to find some favorite recipes to make that use onions, such as French onion dip, French onion soup, onion and cheese sandwich, and onion pancakes.

The second is to finely dice your onions and use a food dehydrator to preserve your onions for long term use and storage.

And the third recommendation is to prepare your onions for your favorite dishes and then place them in the freezer in a zipped freezer bag. You will then enjoy pulling out prepared onions and simply incorporating them into dishes, casseroles, soups, and more.

How long are onions good for when prepared in a dish?

If the onions are cooked in a casserole, soup, or dish then most likely if the dish is still good, the onions will be fine too.

A general rule of thumb for keeping leftovers in the refrigerator is that they will typically last for 3-4 days. After that, they should be thrown out or moved to the freezer.

Can onions go bad?

Yes, onions can go bad. They can grow mold, begin to rot, and can capture harmful bacteria that can make people sick if consumed.

If you think your onion has gone bad, throw it away and use another one instead. Do not take the risk of becoming sick from eating an onion that has gone bad.

Is an onion spice or vegetable?

An onion can be classified as both a spice and a vegetable. An onion is often used to provide flavor or seasoning to dishes so would be a spice. And it’s a vegetable because the plant itself is the portion that can be consumed.

How to tell if the chopped onion is bad?

If a chopped onion is bad, it might smell strange, appear off, or taste off. Chopped onion can begin to grow mold, develop black spots, or become discolored. It might also begin to smell like decomposing food. If you suspect that your chopped onion has gone bad, you should throw it away and not use it in any dish.

How long do cut onions last? Once an onion has been peeled and chopped, if it is going to be eaten raw, it should be consumed the same day. If a chopped onion has been stored overnight, it can begin to grow bacteria and should only be used as a cooked onion.

How to tell if the diced onion is bad?

Diced onion and chopped onion should be treated the same as each other. If you notice any discoloration, strange odor, growth of mold, or visible sliminess, you should assume that your diced onion is bad and throw it away.

Once diced onion has been stored overnight, it runs the risk of growing bacteria and should only be used in cooked foods, rather than consumed raw in recipes such as salads or sandwiches.

Do whole onions go bad?

Yes, whole onions can go bad. It typically takes a whole onion a longer length of time to go bad than chopped onion or diced onion, if they’re stored properly.

The key indicators that a whole onion has gone bad are similar to that of chopped onions. If your onion is beginning to sprout or grow, that could be an indicator that you’d no longer want to use it for cooking.

The bulb of the onion has a tendency to rot at that point.

Do onions absorb bacteria?

There is an old myth that says that if a peeled onion is left by the bed of a sick person, it will absorb the bacteria and take away the illness from that person. There is no scientific evidence that says that this is true.

It is possible, on the other hand, that if a peeled or cut onion is left long enough, it will however begin to grow bacteria and can cause illness if consumed.

What happens if you eat a bad onion?

Can bad onions make you sick? Possibly. Any item that has gone bad has the potential of making you sick if you eat it.

But despite some myths, onions aren’t any more likely to make you sick than other food that has gone bad.

Do onions go bad if not refrigerated?

Yes, they can, but typically it depends on the state of the onion. For example, a chopped onion will certainly go bad after a day or two if not refrigerated, but a whole onion will likely be fine if it’s not refrigerated but is kept in a dry location.

Refrigerating a whole onion will, however, lengthen its shelf life compared to storing it at room temperature.

How long can you keep onions?

You can keep onions for as long as they last, so long as they have not spoiled. Whole onions that still have their peeling will last for several weeks in a cool dry location such as a refrigerator drawer.

How long do green onions last in the fridge?

Green onions typically last for 1-2 weeks if kept in the refrigerator.

How long do cooked onions last?

Cooked onions usually last 2-3 days if stored properly in the refrigerator.

How do I know if an onion is bad?

If an onion is bad, its appearance, smell, taste, or how it feels will be off. See our list of key indicators for knowing how to tell if an onion is bad.

How to tell if a red onion is bad?

If you notice mold, black spots, the onion is mushy, it smells strange, or has a slimy texture, then the red onion is bad and should be thrown away.

Exterior blemishes such as strange spots on the outside of the onion usually represent what is happening on the inside of the onion.

How to tell if a cut onion gone bad?

Cut onion that has gone bad, usually develops a slimy residue on the outside of it, first. It can also grow mold or develop small black spots.

Take a few moments to smell your cut onion and if it smells strange, it has also gone bad. Cut onion should not kept if you suspect it has gone bad. Instead, throw it away.

How to tell if a yellow onion is bad?

To spot a yellow onion that has gone bad, evaluate it by looking at it. If its exterior has any strange color changes such as dark spots or discoloration, it could have gone bad.

If there is a stench in its smell, or the texture is slimy or soft, and obviously if there is mold, your yellow onion is bad. Do not risk eating it. Throw it away instead.

How to tell if a brown onion is bad?

Spoiled onions will start to get dark spots, which eventually grow mold. And if they are slimy in texture or soft when you squeeze them, they’re beginning to rot.

An onion that is beginning to sprout is also an indication of a brown onion that is going bad. Throw away brown onions that have gone bad.

How to tell if a white onion is bad?

Squeeze your onions to determine how fresh they are. If your white onion is soft, has discoloration or dark spots, a bad odor, or is beginning to sprout, then it is likely spoiled and should be discarded.

How to tell if French onion dip is bad?

There is a difference between French onion dip that you buy in the refrigerated section at your favorite grocery store and French onion dip that’s homemade.

Store bought dip has a longer shelf life than dip that’s homemade. But either one should be stored in the refrigerator. If it’s left out more than 2 hours, it should be thrown away.

Indicators that your French onion dip has gone bad includes discoloration, it’s developing a green tint, mold that has developed, a strange or off odor, or strange taste. French onion dip that has spoiled should be thrown away.

barbers french onion dip with garlic

How to tell if Vidalia onion is bad?

A Vidalia onion that has gone bad will display the same characteristics as other onions that have spoiled.

It will have a dry flesh, might begin to sprout, will appear discolored, will become moldy, or will be soft and squishy.

Do not eat Vidalia onions that have gone bad. Instead, throw them out.

How long can onions last in the freezer?

Prepared onions stored properly in a zipped freezer bag and placed in the freezer can last up to 6 months.

How to defrost onion?

To speed up the process of thawing onions that have been pulled from the freezer, you can set them on the counter and allow them to thaw.

Or to speed up the process, you can place the zipped freezer bag of onions in a bowl and submerge the bag in cold water.

Onion Nutrition Facts

The following are estimated nutrition facts for one medium raw onion.

Calories 44
Total Fat 0.1g
Cholesterol 0mg Sodium 4mg
Potassium 161mg
Total Carbohydrate 10g
Dietary fiber 1.9g
Sugar 4.7g
Protein 1.2g

Closing Thoughts: Learn How to Tell If an Onion Is Bad with these Simple Tips

Following are our closing thoughts for knowing how to tell if an onion is bad. Remember to smell the onion for nasty odor, conduct a visual inspection looking for key indicators, and touch the bulb to check for firmness. And if ever in doubt, throw it out.

Should I store onions in a plastic bag?

The proper storage for onions is in a dark place that’s cool and dry. If onions are placed in plastic wrap, chances are that they tend to collect moisture and the first thing they do is begin to form brown spots.

The next thing you know it affects the rest of the onion and you have rotten onions. 

The spoilage of onions is something that you want to try to avoid and the storage method matters both in air circulation, temperature, and moisture level. If you’re going to use your onions right away, you can even store them on the kitchen counter for a few days. 

For long-term storage, however, we recommend putting them in a cool dry place.

The shelf-life of an onion can be quite long for a healthy onion that has the outer layers cured and dried. This includes a nice, papery skin with no mushy spots or mold growth. 

Should I throw away a sprouted onion?

Chances are if your onion has sprouted, then you’re no longer going to want to eat it. This is true for white onions, spring onions, sweet onions, red onions, and an onion bulb.

If you notice an unpleasant smell or a strong smell, your onion is likely on its way to being spoiled or will be within a couple of days. 

Signs of mold indicate spoilage and the presence of black mold is a sure sign that you’re not going to want to risk eating it. Moldy onions should be thrown away. 

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how to tell if an onion is bad

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Sarah is known for her extra fancy yeast breads, melt in your mouth pies, and everything salads. She has won awards as a home cook, and is passionate about helping others feel smarter in the kitchen. Sarah is the cooking genius of the sister duo.

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