How long do cooked onions last?

This article will answer the question “How long do cooked onions last?”, and how to tell if the onions are spoiled?

How long do cooked onions last?

Cooked onions will last 3-5 days in the fridge and upto 3 months in the freezer If stored within 2 hours of cooking. 

Discard the cooked onions if they have been sitting out for more than 2 hours at temperatures between 40℉-140℉. This temperature range is ideal for bacterial growth, hence, referred to as the ‘Danger Zone’ by the USDA.

How to sweat onions?


  • Onions (sliced, diced, or rings)
  • Oil or butter 


Follow the steps below to sweat onions.

  1. In a saucepan, melt some oil or butter. Add onions and cover them with a dampened cartouche. Cover the saucepan with a tight lid and let the onions sweat on low heat.
  1. Check the onions If you see too much steam escaping the pan. When the cartouche becomes dry, re-dampen it. In case the onions at the bottom are browned, do not stir them in the rest of the onions. Your best bet is to start over.
  1. Onions will be done after 10-15 minutes of sweating. They should be perfectly translucent. The onions should be easily smashed between your fingers and should have a mild and sweet taste.

How to store onions?

  1. Like shallots and garlic, onions should be stored in a cool, dry, and dark place away from heat sources like sunlight and stovetop. The pantry or kitchen cabinet works fine.
  1. Do not wash the onions beforehand. 
  1. Do not keep the onions in a pile. The onions at the base of the pile will go bad quickly.
  1. Keep the onions in a ventilated paper bag and leave it open. If you are using a bowl or container, do not cover it and let the onions breathe. Do not use a plastic bag for storing onions. It will block air circulation.
  1. Keep the onions away from ethylene-producing fruits and vegetables like apples, bananas, and tomatoes.
  1. Sliced, cut, or chopped onions should be kept in an air-tight container or freezer bag to seal the moisture and the pungent smell of onions.
  1. Cooked onions should be placed in an air-tight container or freezer bag and stored in the fridge. 

The shelf-life of onions

In the pantryIn the fridgeIn the freezer
Whole onions1-6 monthsNot recommendedNot recommended
Half-cut onionsNot recommended6-10 daysNot recommended
Chopped or sliced onionsNot recommended6-10 days6-8 months

How to buy onions?

When shopping for yellow and red onions, look for the ones with dry and peppery skin. They should have a firm texture and a considerable weight that shows they are not overripe. The onions should not have soft or mushy areas.

When shopping for spring onions, look for the ones with unbruised and frim stalks. The bulb should not be slimy. Leeks should have crisp and firm stalks with no discoloration.

How to tell If an onion is bad?

The worst-case scenario is mushy and soft onions, which is an indication of rotting and happens only if onions have been in direct contact with water.

Whole onions

Whole onions, if kept for too long in the storage, begin to germinate and develop long and slender green stems. In this case, the onion will start to wither developing wrinkled and rubbery outer leaves. The outer leaves can be removed to eat the rest of the firm onion.

The sprouted onion is also edible in most cases. In the case of immature stems, they taste bitter and are not a pleasant addition to your food.

Cut onions

Cut onions will go bad once they start giving off a foul odor and develop a slimy texture. The spoilage is quick due to an increased surface area.  Therefore it is recommended to refrigerate sliced or chopped onions tightly covered in plastic wraps. 

However, the rule of thumb is, a bad onion would have a discolored appearance and/or darkened and soft spots.

Mold growth 

Soot-like patches on the onion are a clear sign of mold growth. This happens due to contamination from the soil and improper storage conditions that favor these bacteria to multiply.  

It is recommended to remove these black pathy areas and store the onion in the fridge after proper rinsing. However, if the mold continues to the inside of the onion, discard it.

Does eating bad onions make you sick?

Eating a bad onion might not have any serious effects. Your stomach might act up a little and obviously, it will taste bad. But food poisoning from eating a bad onion is a rare case.

Other FAQs about Onions that you may be interested in.

How long do diced onions last?

Are onions safe to eat after cutting?

Are pearl onions the same as shallots?


This article answered the question “How long do cooked onions last?”, and how to tell if the onions are spoiled?


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