Mold On Eggs: Are They Safe To Eat? And How To Prevent It

Eggs are a delicious, highly nutritious, and very cheap source of protein enjoyed around the world. So what happens if you open the container so you can begin to create an excellent omelet for breakfast, only to find that your eggs have patches of what looks like mold on them?

Can the eggs still be eaten, is it a sign that the eggs are off and need to be thrown away and how can you be 100% certain it’s mold and not just a little dirt?

In this article we will be fully covering the topic of mold on eggs, answering the questions above in detail and a whole bunch more, so keep reading!

Common strains of mold found to grow on eggshells are Penicillium, Alternaria, and Rhizopus. These strains can have blue, off-white, green, or black colorations, and are made up of powdery, formations of either small dots or larger spiderweb shape growth. Eggs with mold found should be discarded.

Mold on eggs

Do eggs get moldy?

Mold can unfortunately affect many sources of food, and eggs are no exception. As long as the conditions are right, mold will be able to live on any source of nutrients it can find.

For mold to grow it needs a few things, a dark environment, a source of nutrients, an ambient temperature of between 60 and 80 Fahrenheit, and humidity levels greater than 55%.

The main cause of mold growing on eggs is improper storage. Poor temperature and humidity controls during either the storage or transportation processes will create the perfect opportunity for mold to begin growing and spreading across a whole batch of freshly laid eggs.

Organic material left on the outer shell becomes its source of nutrition, and as they are often stored in the dark with very little airflow, if the temperature is not controlled properly, mold has everything it needs, so eggs certainly can become moldy.

Of course, there are strict rules enforced to make sure produce finds its way from the producer to your home in top condition, but these rules are not always met, and accidents can also happen, so whilst it’s uncommon to find a box of contaminated eggs, it does happen.

What does a moldy egg look like?

This is where things get a little more tricky. I am sure you have looked at a freshly purchased egg at some point and thought that it looks a little unclean, they even sometimes still have feathers on them.

This occurs more often in the U.K. where eggs are not washed before being sold, but even in the US, some bacteria and organic material can still be found, even if they appear clean to the naked eye.

The most common blemishes you’ll find, are small patches of a green, powdery substance. This is often a sign of fungal growth, but it can also come in black and white shades.

Is it definitely mold, or could it be something else?

To be certain that what you are seeing on your eggs is definitely mold growth, you should check for spiderweb-like growths of green, black, or white powdery substances.

The most common forms of mold found growing on eggshells are Penicillium, Alternaria, and Rhizopus, which can grow in partially circular patterns.

However, what you think may be mold, could, in fact, be perfectly natural organic matter picked up from the enclosure the hens are kept in. Grit is added to the flooring of chicken coups to prevent them from eating their own feces, the eggs are laid onto the ground, and this grit and dirt can find their way onto the eggshell.

Ironically, much as buying dirty eggs may sound unpleasant, eggs have a natural coating (called the “bloom”), which keeps air and bacteria from permeating the shell and contaminating its contents. If the shells are washed, this layer is removed and the eggs can quickly go bad.

One easy way to tell whether what you are dealing with is dirt or mold is to bring it close to a heat source. Once mold comes close enough to heat, the powdery structure will begin to deteriorate and give the appearance of melting, heat will have little to no effect on the dirt’s appearance.

Are eggs with mold on the shell safe to eat?

If you have conducted the above test and determined that what you are dealing with is definitely mold, the egg should be thrown away. Despite the mold being on the outer layer of the shell because an eggshell is porous, if the mold has been established on the egg for long enough, it may have already penetrated through the shell and into the white and yolk.

Under this circumstance, washing the mold off the eggshell would still not make them edible for the above-mentioned reasons. Mold can be invisible to the naked eye whilst it is developing, so it is not worth the risk to assume once you have cleaned the egg that it is safe to eat.

What happens if you eat moldy eggs?

In the majority of cases, if your eggs have been damaged during transit and have become contaminated with mold or bacteria, you will know as soon as you break them that they are no good.

Look for discoloration of the yolk or white and an unpleasant aroma, if you see or smell any of these things, the egg is no good and should be thrown away.

We’re you to eat an egg that had been infected with either bacteria or mold, you may experience gastrointestinal discomfort, and potentially even salmonella, which can cause diarrhea, vomiting, fever, and stomach cramps.

Were you to notice halfway through a meal that your egg had mold in it and you had only eaten a small amount, you may not suffer any serious issues at all. However, even a small amount of egg that contains salmonella bacteria can make you ill, so if you notice any of the above tell-tale signs of mold or bacteria growth, do not risk eating it.

Can eggs mold in the fridge?

Eggs can be stored at room temperature, and are often sold and stored this way throughout Europe. In the US, it is more common to store eggs in refrigerators. This is because of what was stated earlier about eggs in the US being washed which removes their natural protection against bacteria entering the inner egg.

Once an egg is put in a refrigerator, mold can indeed still begin to grow if the circumstances are correct. A fridge will generally have a fairly high humidity level, due to other foods being stored in it, and condensation caused by warm foods being placed into a cold environment.

If there is any malfunction of the refrigerator, such as a faulty thermostat or damaged gasket, the temperature the eggs are kept can become unstable. This mixture of high humidity coupled with temperatures potentially reaching close to, or greater than 60 degrees Fahrenheit can allow mold to begin to grow on eggshells.

Can hard-boiled eggs get moldy?

Yes, hard-boiled eggs have the ability to become moldy, as boiling the eggs will remove the protective layer on the outer shell, allowing bacteria and mold to penetrate the shell.

A freshly boiled egg will last around seven days if it has not been peeled, but an egg without its shell will last no longer than 3 days before it begins to go bad.

Bacteria is more likely to begin to grow in or around the egg than mold, but as mentioned previously, if the conditions are correct, mold will indeed be able to form on either a peeled or unpeeled boiled egg.

Can moldy eggs be saved?

Unfortunately not, if you discover any signs of mold either on the eggshell or within the egg once it’s been opened (such as black spots on the inside of the shell), they should be discarded.

Often, there will be a pungent smell accompanying the mold growth, which is a sure signal that you should not consume them.

You may think that if the mold is on the outer shell, the eggs can be saved with washing, however, because egg shells are porous, it’s quite possible that the mold has already permeated through the shell and into the white and yolk, so it cannot be safely eaten.

How to prevent eggs from becoming moldy

Finding your eggs have become moldy is a disappointment, to say the least, so in order to keep your eggs fresh for as long as possible, follow these tips on correct storage to prevent mold being able to form.

  • Store your eggs in a room with plenty of airflow
  • Make sure they are stored in a location with a humidity level lower than 55%
  • For people outside of the US, keep your eggs at a temperature no higher than 60 degrees Fahrenheit
  • For US readers, ensure your refrigerator thermostat is functioning correctly, and there is no damage to the gasket which could increase condensation and cause temperature fluctuations

For readers that prefer to refrigerate their eggs, I would highly recommend using a specific egg storage container for fridges. These containers not only help to protect delicate eggs but also provide plenty of ventilation without risking cross-contamination with other food items. Clicking on the links below will take you to Amazon so you can take a look at our recommended products.

Totally Kitchen Egg Holder for RefrigeratorOpens in a new tab. (US)

Hershuing Large Capacity Egg Holder for RefrigeratorOpens in a new tab. (US)

YANJINGHE 12 egg containerOpens in a new tab. (UK)

Vellichor Egg Storage ContainersOpens in a new tab. (UK)


In this article, you will have learned what kinds of mold grow on eggs, whether or not it’s safe to eat moldy eggs, what happens if you accidentally eat moldy eggs, and how you can prevent them from becoming moldy in the future.

Chris Walker

Chris Walker has struggled for several years with mold after buying his own property. After finding the solutions to several issues around his home, he decided to create this site in order to answer as many questions about mold and mildew as possible to help others dealing with the same problems.

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