Dr. Bronner's Products

Dust Mites and Castile Soap

Eeew. To me that’s a pretty icky word in the title there. Dust Mites are something I don’t like to think about, especially not in the context of their residence in my house. However, just slightly below them in my grossness hierarchy is the dust itself. One reason to keep up with regular cleaning is to reduce the presence of dust mites in my house. The idea that dust causes people to sneeze is somewhat valid, but what is of greater concern – and potentially dangerous to asthmatics – are the dust mites which feed on the dust.

I always equated dust with dirt – very fine dirt. I figured we have a lot of it because we have five people and two dogs tracking in dirt from the outside. While there certainly is some dirt in my household’s dust, it’s not at the top of the list. A variety of sources agreed on what this article from Time magazine summed up:

Nearly everywhere, dust consists of some combination of shed bits of human skin, animal fur, decomposing insects, food debris, lint and organic fibers from clothes, bedding and other fabrics, tracked-in soil, soot, particulate matter from smoking and cooking, and, disturbingly, lead, arsenic and even DDT. (Here’s more on that.)

So let me say it again: Eeeeewww!
And dust mites find this medley quite tasty. So where there is dust, there are dust mites. Just to lay it all on the table, the exoskeletons and poop from the dust mites cause an immune system response in sensitive individuals. (Although, I would imagine that inhaling any bug – technically an arachnid here – would be problematic.)

The best habitat for dust mites are carpets and bedding. Such places are sheltered and cozy with lots of nooks for dust and lots of opportunities to snag skin particles, animal fur, lint, and the rest of that list above. In regards to human breathing, however, the bedding is the main concern. By in large, unusual circumstances notwithstanding, we spend more time lying in our beds than we do on our carpets. Fortunately for us, it’s easier to wash our bedding than our carpets.

Here’s where the Castile Soap enters in
As I’ve covered earlier in regards to spraying for ants, Castile Soap dissolves exoskeletons. So, when it comes to treating for dust mites, this particular attribute of Castile Soap once again comes in handy. I use Sal Suds for my everyday laundry – it is slightly better at whitening whites and getting rid of stains. However, for my bedding, I reach for Dr. Bronner’s Liquid Castile Soap – usually the Peppermint, but any one of them will be effective.

Heat also kills dust mites, so with the combo of heat and Castile Soap, there’s really little chance for survival. Bedding should be washed frequently because new mites take up residence regularly. Also, the combo of high heat and frequent washings can take a toll on fabrics, so opt for 100% cotton fabrics with a moderately high thread count (300+).

The recipe*:

  • 1/3 c. (80 mL) Castile liquid soap
  • 1 c. (240 mL) vinegar
  • Hot water
  • Hot dryer
  • If you have an HE machine, cut each of the measurements by half.

Add the Castile soap to the bedding in the washer. Set the washer at the hottest setting. Put vinegar in the fabric softener cup, so that it will be added during the rinse cycle. (Castile soap can leave a residue on fabrics washed in hard water. Vinegar eliminates this residue.) Dry the bedding on the hottest setting.

For my laundry routine, see my post, Green Laundry Care with Dr. Bronners

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Castile Soap Cheat Sheet

Dilute! Dilute! OK! But how much? Print this guide!


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JOY says:

I bought Sal Suds Concentrated, confused

do I dilute it before adding to HE large washer?

I so what to what ratio?


Heather Hartman says:

We see a LOT of dust in the cleaning industry, love this recipe to kill the mites!

Susana Pires says:


1- Is apple cider vinager ok for the rinse cycle? (I’m not a fan of the smell)

2- I used to put cytric acid diluted with drops of lavander oil for the rinse cycle, is it ok to maintain the cytric acid or do you think that’s not as effective as vinager with dr bronners?

Thanks in advance!

Lisa Bronner says:

Hi Susana- I have not used Apple Cider Vinegar for this. I figure that its acidity would serve the same purpose as white vinegar as far as counteracting the minerals in the water and softening the fabric. The only concern is whether the color of ACV might discolor light fabrics. When using vinegar, I have found that once the fabrics are dry, the smell dissipates. You can also scent white vinegar with essential oils.

Lisa Bronner says:

Hi Cynthia- Castile soap interacts with minerals in hard water, causing heavier fabrics and towels to lose absorbency over time. Vinegar counteracts that reaction, keeping fabrics soft and absorbent. If you have don’t have hard water, you can do without.

William Kilfoyle says:

We have a small stackable washer and dryer we live in an apartment. How much of your soap do we use in the washing machine? Thank you.

Lisa Bronner says:

Hi William- I know stackable washers can be as small as less than 2 cubic feet of washing capacity. If that is the case with yours, use about 3 Tbsp. Castile, or 1 Tbsp. Sal Suds.

Lakshmy says:

Hi Lisa,
I have heard using soap instead of surfactant in washing machine can cause the machine to breakdown .

Have you heard of this or have any information or research around this topic?

We have recently switched to Dr Bronners.for body and face wash and pending this, hopefully looking to move our laundry to your castile soap as well.


Lisa Bronner says:

Hi Lakshmy – Great to hear you’re giving our soaps a try! Soap is a surfactant, so there’s not a difference on that front. My guess is that someone is trying to make the case that detergents are better than soaps. Both soaps and detergents are surfactants, which means they break the surface tension of water, a key part of cleaning. There isn’t a reason soaps would harm a washing machine. My guess is that perhaps that was a marketing pitch.

Debra says:

If you are using the peppermint Castile liquid soap as an all purpose liquid hand soap, should you dilute it?

Lisa Bronner says:

Hi Debra- Use 3-4 drops directly on hands, or it works great in a foaming pump dispenser diluted at a ratio of 1 part soap to 3 parts water.

Natalie says:

Hi! The washing machines in my building use hard water and do not have a fabric softener cup. Should I add the vinegar together with the Castile soap or just use less Castile soap?

Lisa Bronner says:

Hi Natalie- When mixed together, vinegar causes Castile Soap to unsaponify and turn into a goopy mix. Based on what I’ve read and comments from a few readers, I’ve heard adding vinegar (instead of fabric softener) to a Downy ball works when there’s no fabric softener compartment. If you give it a try, let me know how it goes!

Nancy Wood says:

We have hard water, too. I’ve been adding Borax to the wash cycle to soften water; is that okay?

Lisa Bronner says:

Hi Natalie- There’s no interaction between Borax and Castile Soap. I choose not to use Borax because it’s a skin irritant and any left of fabrics could be problematic.

Megan says:

If I don’t have hard water, is it necessary to add vinegar to the rinse cycle?

Lisa Bronner says:

Hi Megan- When used in hard water conditions, Castile Soap can cause fabrics to lose softness and absorbency. Vinegar counteracts this. If you don’t experience that, you can skip the vinegar rinse.

Christine Brown says:

Hi! Im slowly but surely transitioning to nothing but natural ingrediants & Dr Bronner’s. What do you recommend for the mattresses. I keep mattress covers on them, but you know, those dust mites are persistent & micro particles of ick still get threw & into the mattress. As well as lint & even sweat, dispite the water proof mattress cover. Thanks to you & your family for these wonderful products.

Lisa Bronner says:

Hi Christine- For surface cleaning a mattress, I use one of my All-Purpose Sprays – either 1 Tbsp of Sal Suds in a quart of water or 1/4 cup of Castile. Spray the mattress lightly and wipe with a damp cloth. Allow to air dry fully. The key is to be sure not to have moisture soak into the mattress where it might not dry and may mold. Another option is to spray the damp cloth with the a bit of the All-Purpose Spray and then wipe the mattress. Other readers have suggested steaming the mattress with a garment steamer, as heat is effective on dust mites, but this isn’t something I’ve tried personally.

Kyra says:

Hi Lisa, is using 1/2 cup Castile soap along with 5 cups water, washing and baking soda effective laundry detergent?

Lisa Bronner says:

Hi Kyra – Sorry for my delay here. If all that is going in to one load, yes that’s a good amount of castile. You could even do with a little less Castile. Using both washing soda and baking soda might be unnecessary, since they both do the same thing. Washing soda is stronger than baking soda and might wear your clothes down faster. Unless you’re washing really grungy loads, you might just want to go with the baking soda.

Amy says:

Hi Lisa,

Would Castille soap be effective for lice? I have never actually had lice nor have my kids but they’re about to go off to school and I’d like to do some preventative research!

Lisa Bronner says:

Hi Amy- Lice is one of the nastiest four-letter words in my house. Some people have found that washing hair with Tea Tree Castile soap and using a very small amount of coconut oil in the hair can keep lice at bay.

Daisy Berru says:

Hi thank you for this recipe. But what about for everyday laundry like clothes? I’ve seen recipes where it’s a cup of Castile soap dissolved in a gallon of water with soap. Would that be ok for baby clothes ?

Lisa Bronner says:

Hi Daisy- Castile Soap works great on baby (and grown-up!) clothing. Use 1/2 cup Castile Soap with 1 cup vinegar added to the rinse cycle. The vinegar keeps fabrics soft and absorbent. For extra whitening/brightening add 1/2 cup baking soda in with the Castile Soap. Halve these amounts in an HE machine. For more, here’s my blog post on laundry:

Erica says:

I am going to try this on our bedding! Thanks so much.
What about the mites that could be in our carpets (we rent – otherwise I wouldn’t have any carpet!) how do we eliminate them there? We do not own a carpet cleaning machine and can’r rent one (at least for the time being) should I spray a solution on my carpet and then vacuum?
Thanks so much for your posts – we have been using your soaps for several years and I am trying to transition to using them to clean the rest of our house!

Lisa Bronner says:

Hi Erica- Thorough, frequent vacuuming is the best option for potential mites in your carpet. I don’t advise spraying the carpet with a soap solution and then vacuuming. The amount that you would have to spray the carpet would likely be way too much moisture for a vacuum cleaner to handle. It would likely damage it.


Lisa Bronner

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Castile Soap Cheat Sheet

Dilute! Dilute! OK! But how much? Print this guide!