Is Moldy Soap Safe To Use?

Have you had mold grow on your soap? You probably threw it away (just like me)! But have you never wondered if the soap is still usable even with mold/bacteria in it?

Is moldy soap safe to use? It is not recommended to use soap with mold/bacteria in it. Your skin might get irritated or you might get infected if you have a cut or a wound. Scraping off the surface might give you the impression of safety but, bacteria would still be in your soap.

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The main reason for us to use soap is to clean our hands from dirt and wash of germs we catch on during our busy working day. But, if you have mold on your soap and you plan on using it, stop right here and read this first before going further.

Many people believe that since it’s soap, it cannot harm you even if you see spots on it or it smells bad, this cannot be further from the truth I am afraid.

What does mold in soap look like?

There is a good reason why this question is relevant because there is a lot of confusion around this subject. Many people don’t really know the difference between DOS and mold/bacteria growth. Both of them are independent issues but can occur at the same time.

Mold/Bacteria growth:
If your soap has black or dark spots on them and smells really bad, in that case, we are looking at mold/bacteria growth. How and why this happens will be discussed later on.

Dreaded Orange Spots (DOS):

If your soap has DOS (dreaded orange spots) on it, then this is rancidity. This indicates your soap has decayed, and the cause of this is the oxidation of “soft” oils in your soap. Rancidity can happen in different ways, such as hydrolytic rancidity or microbial rancidity.

There are a few more types, so if you wish to know more about it, just do a quick search online.
A significant difference between DOS and mold/bacteria growth is that there is no bad smell; however, the fresh smell your soap should have may have disappeared, or it might smell slightly musty.

Another big difference between them is that rancidity only happens when the ingredient has passed its shelf life, while mold and bacteria can occur at any time.

Soda ash:
I saw people asking on forums if they had mold on their soap while it was just soda ash, so I thought I’d give a short explanation. Soda ash occurs quite often when making cold process soap; it forms when lye (which is still unsaponified) reacts with naturally occurring carbon dioxide in the air.

It is harmless but can be very frustrating as it creates an uneven white film on your bars and makes it look ugly. But there is nothing wrong with using it, so no worries there.

Should I use soap that has mold on it?

Let’s see, would you put anything that has bacteria grow within on your face? I know I wouldn’t, so why would you do that with a soap?
Some people online would tell you to scrape off the surface that as mold and use the rest, but the idea of putting something that might have bacteria or fungus on your face is simply not ok.

Using moldy soap might cause rash or skin irritation, or worse, you might get infected if the area you use soap on has a cut or a wound.

Earlier, we talked about the differences between DOS and Mold/bacteria growth. Another big difference between the two is that you can still use soap that has DOS in it, but that is not the case with moldy or soap.
With DOS, your soap might not have the same effect. It might not lather anymore, but it’s still considered safe to use.

Why did my soap grow mold?

If you make cold or hot process soap, the soap’s pH level should not allow for mold to grow, even without preservatives. But, it’s a different story if you are using additives like fresh ingredients. Like natural fresh herbs and fruits you would eat every day, they all go bad eventually and have mold/bacteria grow in them.

Additives are added after the saponification process, which means that they do not change in structure and are still prone to go bad. Even if the additive is something like milk powder.

Earlier I mentioned that without preservatives soap without any fresh additives will not have a mold or bacteria problem. Well, in case you have fresh ingredients in your soap, preservatives will still not save you, I am afraid.

Preservatives are used to prevent mold and bacteria from occurring in products containing water, such as lotion or emulsified scrubs, but they cannot avoid mold growing from fresh additives.

How can you prevent mold on soap?

The short answer, there is no way to prevent it. I am sorry, this is probably not what you expected, but there is no way for fresh ingredients to stay fresh for an extended period of time.

It is the same thing as if you would take fresh ingredients and leave them on the counter, what would happen, you think? They will turn brown and eventually bacteria/mold will grow in them.

The only way to avoid having this problem is to use your soap before things start to change for the bad (or put a validity date on the soap in case you wish to sell it). An easy and simple way to know how long it stays fresh is to make a batch and keep an eye on when it starts to decay and grow mold on it.


First, make sure to confirm you have mold/bacteria growth, you can easily mistake one for the other. Moldy soap looks like brown or black spots, and it usually smells really bad.

If you have DOS on your soap, you can scrape it off or even use it just as it is.

If you have soda ash on your soap, there is nothing wrong; you can simply use it but might want to check how to solve your ash problem.

If your soap has mold/bacteria growth, it is not recommended to use.
You can scrape the surface or just cut a chunk out of your soap, but you are still taking the risk of bacteria lingering within your soap, which might cause skin irritation or even infection if you have a cut or a wound on the area you used the soap on.

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