How To Tell If An Onion Is Bad- Warning Signs And Preservation Tips

Onions are kitchen ingredients that almost everyone buys in bulk because grocery shopping is only easy when it’s a list. As much as onions go into about every meal, they don’t stay around for too long. Then, how can you tell that your onion is bad?

You should be able to identify a bad onion to keep it from soiling the rest and ending up with a lot of bad onions. Don’t get confused… below is everything you need to know about what a bad onion looks like.

What is an onion?

An onion is a vegetable bulb of the species Allium cepa. It is an edible plant with tightly packed concentric layers. Onions are known for their distinctive smell and taste. There’s no way you can hide an onion bulb in a room.

Onions are diced, sliced, pureed, chopped, grated, and cut into rings to add flavor to meals. Moreover, eating onions raw or cooked has a lot of health benefits. Onions have antibacterial properties that help to protect the body and boost immunity.

Furthermore, they are also anti-inflammatory, can help improve respiratory issues, improve eyesight, help you get clear skin, and make your bones healthy.

How to tell an onion is bad?

Here are telltale signs that your onion is bad:

1. Presence of mold

Mold growth is one of the first things you’ll see on a bad onion. It first manifests as brown spots. Then, you may notice white, grey, or green growth on the body of the onion.

The first place you’ll see the mold is on the papery skin. If you cut an onion and still see mold growth on the inside, you should throw it away already.

However, if there are no molds on the inside, you can just peel off the mold on the papery skin and wash the rest with water.

2. Slime

Slime is common with cut onion that is going bad. The onion may also have mold growth and will feel slimy when you touch the surface.

Try to cut off the slimy surface and feel the new surface. If it is still slimy, you should throw it away.

3. A funny smell

Onions naturally have a strong smell. A bad onion will smell foul and rotten. The smell of onions can help you identify a bad onion that looks and feels good on the outside.

If you’re not sure of the smell, try to identify a stench of compost. Once you get that, discard the onion.

4. Skin discoloration

Some mold growth may appear as skin discoloration, which may look like the natural skin of the onion.

When you can’t tell the state of an onion with the outermost skin, peel off the skin and examine the concentric layers to check for any discoloration.

5. Mature sprouts

Naturally, sprouts do not mean an onion is bad, but when the sprouts are too mature to be eaten, the onion could be going bad.

Cut off the sprouts and the affected area to see if the other part of the onion still looks good and firm. Otherwise, throw everything into the bin.

In addition, one sprouting onion can make the others go bad quickly. Therefore, you should always separate sprouting onions from the rest.

6. Pulpy flesh

Bruised flesh or flesh with lots of spots are telltale signs that tell you your onion is going bad.

Sometimes, the pulpy flesh is hidden behind the papery outer skin. When you cut your onion and notice this, it’s no longer fit for consumption.

Also, a very dry and crisp flesh void of moisture is a sign that the onion has gone bad.

How do you tell red onion is bad?

A bad red onion will no longer have the naturally sweet taste of fresh red onion.

Bad red onion can be identified by the wet spots on the flesh and thick woody sprouts on the head. Additionally, a bad red onion will feel lighter than fresh red onion.

How do you tell white onion is bad?

You can identify a bad white onion by the presence of brown or dark spots which are signs of mold growth.

They also develop soft, mushy skin and a pungent smell. With these signs established, you should throw the onion away.

How long can an onion last?

Under proper storage conditions, a whole onion will last up to three months or longer, depending on the climate. A raw, cut onion will last a few days to one week if you keep it in a refrigerator.

Cooked onions will last only three days in a fridge. However, it is not advisable to store cooked onions.

Do onions go bad in the fridge?

Yes, they do.

Whole and cut onions will go bad in the fridge if you store them for too long. Naturally, onions easily absorb moisture, and it worsens when they are refrigerated for too long.

When onions exceed 10 days in the refrigerator, they become wet and mushy and spoil much faster.

What happens if you eat a bad onion?

Your mouth gets the first hit after you have eaten a bad onion. The unpleasant, sour, and acidic taste could mess up your taste buds for some minutes. Also, the taste of a bad onion may slightly alter the taste of your meal.

Although not so common, you may experience stomach discomfort, nausea, and a sickly feeling. However, none of these pose a threat to one’s health.

How to preserve onions

  • Preserve peeled or cut onions by storing them in the fridge
  • Store peeled onion in an airtight container or resealable bag before refrigerating
  • Keep onions in a cool environment, preferably out of the fridge
  • Also, make sure your onions are out of the reach of moisture. Keep them dry
  • Allow air circulation where you store your onions. Do not pile them on each other
  • Avoid storing onions and other foods together
  • If you keep your onions in a bag, use mesh or brown bags with small holes
  • Additionally, always check for bad onions and remove them
  • If you’re storing onion in a refrigerator, avoid opening the door of the fridge too frequently to avoid bacteria contamination


Why do spring onions become slimy?

If your spring onion is slimy, it is a sign that it is already mature. This slime is not present in smaller spring onions.

Can you eat a soft onion?

It is not advisable to eat a soft onion. Soft and mushy onion layers are already going bad, and you should dispose of them.

Can you get sick from green onions?

The harvesting process of green onions exposes the onions to contamination.

Although they are a rich source of nutrients and can help improve many health conditions, eating raw green onions can also expose you to bacterial pathogens.

Can you eat an onion that has sprouted?

Yes, you can. An onion with sprouts does not signify anything health-threatening. Besides, onion sprouts are a rich source of protein.

However, if you do not feel comfortable eating onion sprouts, you can cut them off and use the rest of the onion.


Raw, cut onions are common in households. And they are almost unavoidable because sometimes, you only need a little onion to add flavor to your dish.

But this could be the reason your onions go bad quickly and waste. Moreover, a whole onion can also go bad under certain conditions.

Therefore, you should be vigilant and examine your onion bulb before you use it. And the best way to store your whole onion is out of the refrigerator, the freezer, and anywhere cold.

I hope you found this article interesting and helpful. If you just found out all the onions you have left have gone bad, You can try out any of these onion substitutes and continue your dish,

Thanks for reading.