Does Ammonia Kill Mold?

This post may contain affiliate links. Read our full disclosure.

Ammonia and mold. That is a VERY loaded topic and one that I will try to break down into digestible parts. There is a lot of controversy about whether or not ammonia kills mold and mycotoxins.

You can’t talk about ammonia and mold without discussing Dr. William Croft. He is the doctor whose research and experiments confirmed that ammonia is a powerful mold killing agent. However, Dr. Croft is a very controversial figure which has led to a lot of back and forth about his work and conclusions.

Before we get into the belly of the beast, let take a look at a couple of basic things about ammonia and toxic mold.

A spray bottle with ammonia being sprayed to remove mold

What Is Ammonia?

Wikipedia defines ammonia as “a compound of nitrogen and hydrogen with the formula NH3. The simplest pnictogen hydride, ammonia is a colourless gas with a characteristic pungent smell.”

Does Ammonia Kill Mold?

Now we get back to Dr. William Croft. Dr. Croft is a research pathologist/scientist from Madison, WI, studying human and animal diseases.  He was granted a Doctor of Veterinary Medicine degree in 1970 and has a PhD in Medical Pathology which he earned in 1975.

For the past 30+ years, Dr. Croft has dedicated a significant portion of his studies to toxic mold as a group of poisons that contain mycotoxins and the impact that has had on human and animal health.

In his experiments Dr. Croft was able to confirm that ammonia not only killed the mold spores but also destroyed the molecular structure of the mycotoxin that is so dangerous to humans, animals and most forms of life.  

Dr. Croft is an interesting fellow to be sure. He certainly has fought hard to show the world that ammonia IS the best solution for controlling mold and mycotoxins. 

If you have some time on your hands, you can listen to a 22 minute interview that Dr. Croft did with Before Its News and hear his thoughts on the history of toxic mold (which is quite fascinating if you don’t know it) as well as how he came to his conclusion that ammonia is the best solution to killing mold spores and mycotoxins.

But back to the topic at hand. Does ammonia kill mold and how?

I looked at all of the research Dr. Croft had to offer and combined that with other research (cited below) to determine if ammonia was really as effective at killing mold as Dr. Croft suggested. I took a look at the agricultural use of ammonia which has been going on for centuries. There was a lot of evidence to support that ammonia has proven to be an efficient and safe practical solution to mycotoxin removal in foods and animal feeds.

I came to the conclusion that yes, ammonia does kill mold spores on NON-POROUS surfaces. Surface mold and mold spores on tile, ceramic, granite, porcelain and the like can absolutely be cleaned with ammonia. For those of you wondering “will ammonia kill mold on wood furniture and other wood items” the answer is no. Absolutely not. It cannot penetrate ANY surface rendering it useless on porous items where mold hides in all the little nooks and crannies.

How Do You Use Ammonia To Kill Mold?

First and foremost you open all windows, turn on all exhaust fans, and wear a respirator.

Household ammonia (clear ammonia) is diluted to 3% – 5% concentration so there is no need to dilute it further however, since it is so toxic, I do suggest making a 50/50 mix of ammonia and distilled water. It must be distilled water!

  • Put your clear ammonia and water mixture in a spray bottle.
  • Saturate the areas of concern with the ammonia spray.
  • Let it sit for 2-3 hours.
  • Wipe any excess moisture off the surface and then clean the surface with plain old water.

Does Ammonia Remove Mold From Clothes?

Yes, it does. But I have a HUGE word of caution. I learned a tough lesson and don’t want others to make the same mistake.

While ammonia works to remove mold from clothing, I would NOT suggest you go that route. Why? Chlorine. That’s why.

Chlorine and ammonia make a very toxic, fumey cocktail when combined. It causes serious respiratory issues. I was naïve and washed my clothing in ammonia. We had chlorinated water. While no one died or was critically impacted health wise, it sure did wreak havoc on our lungs for a few days. Unless you have a water filter that removes ALL chlorine from your water, do not wash your clothes in ammonia.

You can use one of these three laundry additives to remove mold spores and mycotoxins instead.

Pros of Using Ammonia To Kill Mold

  • Ammonia is cheap and easy to find.
  • 100% effective at killing all mold species on non-porous surfaces.

Cons of Using Ammonia To Kill Mold

  • It is a VERY harsh, toxic chemical.
  • Ammonia is a skin and eye irritant. You must use a respirator when using it.
  • You should only use ammonia in a very well vented space.
  • Pets and children should not be in the area for 3 hours after using ammonia.
  • Ammonia only works on hard non-porous surfaces but it is ineffective at killing mold growing in porous material such as wood or drywall.
  • You NEVER want to mix ammonia with any amount of bleach as it will create highly toxic and potentially deadly fumes. When it comes to killing mold, you basically don’t want to use bleach anyway.

Cost of Ammonia

The brand I recommend will run you about $7 on Amazon for 32 ounces.

Where To Buy Ammonia

Any grocery store, big box store, hardware store, drugstore, and even some convenience stores. Amazon always has several choices as well.

Is Ammonia My Go-To To Kill Mold?

Not typically. Like I mentioned above, it is a very harsh chemical. I prefer to steer clear of OTHER things that are toxic when dealing with a toxic substance like mold. There is only one product that I trust completely to kill both mold spores and mycotoxins. If you are interested, you can check out my favorite product to kill mold and mycotoxins here.

Want To Learn More About How Ammonia Kills Mold? Check Out My Sources:

You Might Want To Check Out These Posts As Well

A bottle of ammonia to kill mold

Leave a Reply

Your email address will not be published. Required fields are marked *


  1. Tony Zamberlin says:

    Great article. Too bad it’s so toxic for us and animals or I would consider using it.

  2. Dr. Kerry says:

    No one in their right mind would spray ammonia on a wall (as pictured). Nothing replaces proper remediation. Croft recommended ammonia for clothing, not building structures and he is correct in that regard.

    1. Sadly I have had plenty of people contact me who have done just this. You and I might know that nothing replaces proper remediation but the vast majority of people do not know this. This is why I try to cover every base. I’m not speaking to an audience who is already well versed in mold for the most part. I am speaking to an audience who are at ground zero and don’t know what to do or where to start, even possibly have already tried and failed at a DIY option.

  3. Hi Jennifer,

    I’m in a really bad situation and I had to abandon my home. There’s physical mold in the structure of my home but inside I inadvertent contaminated my entire home when I removed a carpet. No one knew it was mold right away, we just thought it was carpet padding stuck to the concrete so this has been walked through and had fans blowing etc. It’s gone now but there’s millions of dormant spores inside my home now. I have no clue how to handle it and I’m flat broke because of everything. All I want to do is be able to go in and rescue my dog’s paw prints and pics of my daughter growing up, basically everything sentimental to me. I have PPE but still I am extremely sensitive and adding to that, I’m actually very scared to go back in. I listened to Dr. Croft’s interview and he had mentioned misting ammonia into the air. If I were to do that and it were to negate some of mycotoxins in the air, do you think if I waited for the ammonia to dissipate and then went in, it would help any? There’s a massive amount of dormant spores and don’t know if I should mist a heavy amount or could it possibly do more harm than good? Could the spores released more toxins bc they feel threatened by the ammo or is it only mold colonies that have the ability to release toxins. Thanks in advance.

    1. Hi Sue! Sorry for the delay. I had major surgery a month ago and am just now getting back to work. This is a loaded response. Did you already go back into the home or do you still need advice?