Are Slimy Mushrooms Bad?

It often happens that mushrooms in your fridge become slimy quickly. Most of the time you don’t want to throw them away because they cost money. You’d rather find a way to use them, but when mushrooms are slimy, are they bad?

When mushrooms are slimy, it means they are turning bad. Slimy mushrooms means they have bacteria or fungi growing on them. These microorganisms are causing the mushroom to decompose which ruins their taste and can potentially make you sick.

Slimy mushrooms are a sign that your mushrooms are turning bad 1. There are other signs mushrooms are turning bad which I’ll inform you about. In addition, this blog post will tell you how you can prevent your mushrooms from becoming slimy. 

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Are Slimy Mushrooms Bad?

Typically, fresh whole mushrooms last from 7 to 10 days, after that they start turning slimy. This means some kind of bacteria is growing on them, causing them to decompose. On occasion, mushrooms may last up to two weeks.

When they first start to become slimy, many people will cook them to prevent them from turning badder. This will extend their shelf life but if they have been slimy for a long time, throw them away. 

There are ways to extend mushrooms shelf life before they become slimy. One way is to store them unpeeled in the fridge inside a paper bag 2. 

Another way is to brown the mushroom in a little bit of olive oil and garlic. Place them into a sealed container in the fridge. 

For a longer-term option, you can freeze mushrooms. In that case, you need to cook or steam them first and then put them in the freezer. Frozen they can last for about 6-12 months.

Steaming mushrooms before freezing allows them to last longer. I wrote a whole blog post on freezing mushrooms which covers everything you need to know step by step. You can check out that post by clicking here, The Complete Guide To Freezing Mushrooms.

Can You Get Sick From Slimy Mushrooms?

Ingesting slimy mushrooms can make you sick. Typically symptoms may include nausea, stomach cramps, vomiting and diarrhea. In rare cases, the toxins from older, bad mushrooms can cause botulism, E.coli or salmonella.

If you’ve eaten slimy mushrooms and you feel sick, contact your doctor. The more serious illnesses noted above can be fatal.

It’s safe to say the best thing to do is throw away slimy mushrooms instead of risking sickness. 

Mushroom Fun Fact: Mushrooms made the Environmental Working Group’s Clean Fifteen List for 2020 3.

Can You Wash Slimy Mushrooms?

You can wash the slime off of mushrooms, but that doesn’t mean they’ll be safe to eat. Slimy mushrooms that have been washed can make you sick since the bacteria are growing on them.

Slimy mushrooms may ruin your dish because washing them won’t get rid of the mold and bad flavor it causes. Mold can burrow deep into mushrooms, which means it may not be visible on the surface. Besides tasting bad, some types of mold are harmful if ingested.

Keep them dry to prevent the growth of mold and bacteria on the surface. Do not wash your mushrooms because they are very porous and absorb water like a sponge. Wash them quickly and scrub them gently with a soft brush just before cooking them 4. Even better, use a dry cloth or paper towel to wipe any dirt off of mushrooms instead of using water.

What Happens if You Cook Bad Mushrooms?

Bad mushrooms that have been cooked may cause illness. The slimy mushrooms may contain bacteria and mold which may cause stomach cramps, nausea, vomiting or diarrhea.

You’ve noticed your mushrooms have gone slimy, what now? Don’t think cooking them will make them okay to eat. Make sure to go through the package carefully and remove any mushrooms without slime or any signs of going bad.

Many times only a few of them have started to turn. If you have doubts about any of them, discard the mushrooms. Your always better safe than sorry.

Many people have the opinion that a small amount of slime or a wet feel on a few mushrooms will not cause harm. Typically, they’ll wash the slim off and cook them right after cleaning them. Most of the time, they’ll be okay and likely won’t get sick. 

Even though, it’s best to avoid them because they could cause food poisoning or at the very least, nausea. Washing the mushrooms in between good and bad, as well as the good ones, gives you the chance to check them all thoroughly.

Other Signs Mushrooms Have Gone Bad

Besides being slimy, mushrooms gone bad may also display other signals they should be discarded. The following represent signs a mushroom has gone bad:

  • Slimy.
  • Wrinkles.
  • Dark Spots.
  • Their color has darkened.
  • They smell ammonia-like, fishy or pungent.
  • They have been in the refrigerator for more than two weeks.

What To Do With Old Mushrooms?

Old mushrooms should be uneaten and discarded. Slimy mushrooms can be included to your compost. Since the bacteria have already started decomposing your mushrooms, it will accelerate the process. 

Mushrooms have naturally high levels of potassium, copper and phosphorus. They are the only good source of selenium from produce. By adding mushrooms to your compost, all these minerals will become a part of the completed compost. Your garden and plants will have access to these minerals making your compost even richer 5. 

The organic material in compost is mostly decomposed by fungi, such as mold, yeast, and mushrooms. When you put your mushrooms in a compost pile, it speeds up decomposition by spreading fibers and cells that break down tough organic materials. It is especially good to use them when the composting conditions are not good for bacterial decomposition because the mycelium in fungi can complete the task.

Mushrooms have a vast mycelium network. Enzymes break down into basic sugars and nutrients. This efficiently feeds plants and helps them grow faster when the network expands. When nutrition is returned to the soil, carbon dioxide is released for plants to breathe. Then the plants give the fungi substance the mushrooms can’t produce on their own.

Putting mushroom in your compost will directly benefit the vegetables and plants that you are growing.

What Do Mushrooms Smell Like When They’re Bad?

When mushrooms are bad, they can smell ammonia-like, pungent or fishy. A mushroom that hasn’t turned bad produces an earthy smell. If a mushroom smells bad it should be discarded.

A good habit is to smell your healthy mushrooms prior to cooking them. It will help you identify what they are supposed to smell like which will make it easier for you to identify a slimy mushroom gone bad.

How Long Do Mushrooms Stay Fresh For?

The following are how long a mushroom stays fresh before turning bad:


  • Raw Mushrooms can last up to two weeks but typically the average time is two days.
  • Sliced raw mushrooms can last up to 5-7 days.
  • Cooked mushrooms can last up to 7-10 days.


Frozen mushrooms may last up to 9-12 months in the freezer.

Many factors can change how long a mushroom lasts before turning slimy. Refrigerator temperature, packaging, moisture levels and the freshness of the mushroom when you purchased them. These factors can always affect the typical time a mushroom stays edible.

If you decide to freeze them 6, be aware the mushroom will lose some of its quality, nutrients, flavor and texture.

How Do You Pick Mushrooms?

Pick mushrooms with the following characteristics:

  • Appear dry but not wrinkled.
  • They feel firm and not mushy.
  • A mushroom should maintain a smooth appearance.
  • Appear plump.
  • No brown spots or darkened color.
  • Smell fresh and earthy.

Are The Mushrooms In My Yard Poisonous?

Mushrooms in the yard may be poisonous and make people and pets ill. If you have small children or pets that play in your yard, the mushrooms should be removed before anybody ingests them. In case of accidental ingestion, identify the mushroom eaten, so physicians or veterinarians can make a better diagnosis.

Some yard mushrooms are edible and perfectly safe to eat but most wild mushrooms are not edible 7. If you are unsure about what kind of mushroom you have it best to follow the advice above and not cook them to consume in your dishes.

Read Next – More Food Storage

How To Freeze Spinach

A Guide To Storing Asparagus The Proper Way

Food Storage Bags Vs. Freezer Bags – What You Need To Know

Article Resources: Foods For Anti-Aging follows strict guidelines to ensure our content is the highest journalistic standard. It's our mission to provide the reader with accurate, honest and unbiased guidance. Our content relies on medical associations, research institutions, government agencies and study resources. Learn more by reading our editorial policy.
  1. USDA: Mushrooms[]
  2. Fruits & Veggies: Mushrooms[]
  3. EWG: EWG’s 2020 Shopper’s Guide to Pesticides in Produce[]
  4. FDA: Selecting and Serving Produce Safely[]
  5. Oregon State University: What is mushroom compost?[]
  6. National Center for Home Food Preservation: Freezing Mushrooms[]
  7. The Mushroom Council: FAQ[]

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