young woman applying antiperspirant to her armpit

When people hear the word “microbiome,” they often think of intestinal bacteria. (As well they should. For fascinating insight into some unexpected ways the intestinal microbiome affects our health, you may wish to listen to our one-hour interview with Dr. David Perlmutter, author of Brain Maker.)

We now know that there are more bacterial cells than human cells in any individual person. What most people don’t consider, however, is the microbiome of the skin. We are teeming with microbes adapted to their own particular niches.

The Microbiome of the Armpit:

One place, in particular, has a rich microbiome, and that is the armpit. This part of the body hosts a lot of bacteria, and the ecology of the bacterial communities in the armpit varies greatly between individuals.

Researchers in North Carolina conducted a study that compared bacterial communities between people who use underarm products such as antiperspirants and deodorants and those who do not. There were striking differences.

Differences in Armpit Ecology:

Not only were there many more bacteria in product-free armpits, the mix of species was quite different. Stopping the use of deodorants or antiperspirants resulted in an increase of bacteria that could be cultured. The dominant species still differed from those in armpits not accustomed to hygiene products.

Unfortunately, the authors are unable to say whether these changes have an impact on human health overall. Perhaps future studies will shed light on the impact of antiperspirants and deodorants over the long term.

Peer J, online Feb. 2, 2016

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  1. Dobermom

    I’ve been using MOM for some time now, except for special occasions because frequently I would still feel sweaty or notice some odor. Recently I added a few drops of tea tree oil to the sprayer and since have not gotten sweaty or had any odor. Now I will admit, it’s still winter, so the jury is still out, but it seems a big improvement thus far. I suspect too much tea tree oil could be harsh on the skin, and maybe cause problems for those that are sensitive, but so far it has worked great for me.

  2. Ebm

    When the first fist size huge crystal deo block was available in
    an upscale dept. store, I started using it until it was considered
    bad because of alum. Tried everything natural avail. but nothing
    worked. Now I have the best results all day with 50/50 white
    vinegar and water. Vinegar kills bacteria. If that is bad, I have
    to live with that, gotta use something, stinky clothes are
    awful and MOM was not strong enough for me.

  3. Terry

    I had some very stinky armpits from intensive gardening. I cleaned them extra good with soap, rubbing alcohol and mouthwash. I think I killed all the good germs as they are now extremely difficult to keep stink-free. I have to scrub each 3 minutes with soap. I use the MOM as deodorant and previously only used deodorant, never antiperspirant, so I have never used a product with aluminum on them.

  4. Anne

    I very rarely use anything on my armpits other than soap when I take a daily shower. Years ago (close to 30) someone told me he was sensitive to antiperspirants and never had any problem just by washing daily. He was right. Perspiring has never made me smell bad. The only time I’ve detected an unpleasant smell was from something in the fabric I was wearing that seemed to react to my skin. There are times when I seem to perspire more, and it’s usually when I’m chilled, of all things. Otherwise, even in the heat of summer, it doesn’t bother me, and I don’t smell!

  5. Helen M
    Modesto, CA

    We, in this country, have been trained to find underarm odors offensive. Not so in other countries, and I remember reading some years ago that we were considered obsessive about being clean. Witness our use of all the anti-what-not products that have our young with under-developed immune systems.

    My underarm microbiome must constantly be evolving because products stop working on me. When I first used Mitchums, once every two or three days was enough. Then daily was not enough. Ditto with the MoM product. I began with a bottle of the white stuff which had turned into a goop when the bottle was almost empty. After reading here about the bleach, and affirming it, I ordered the PP product. I am not yet done with the first bottle, but it does not last me thru the day. I don’t know if this resilient colony is a good or bad thing.

    Coincidentally, or not, I eat a lot of raw sauerkraut. When that bottle is half empty, I slice cucumbers into it, they ferment in a day or two, perfect taste for me. I grew up with barrel sauerkraut from the east side of NYC, not too easy to find here in the central valley of CA, to say the least. With the recent emphasis on gut bacteria health, stores like Trader Joe’s are now offering a similar product. Yet with all my years of good eating, I suffer with many complaints that are common with sick guts. Go figure. Wonder how much inheritance has to do with it.

  6. Mary

    The FDA requires products labeled antiperspirants to contain aluminum. I quit using such products a number of years ago.

    Check out Peoples’ Pharmacy MOM deodorant products instead.
    No heavy metals at all.

  7. Sandra

    My husband (age 70) has never used any underarm antiperspirants or deodorants. He does not have any odor on his body or his clothes. I’ve always been amazed at this since I have always used deodorant and experience underarm odor when I haven’t used it. I wonder if the odor would eventually go away if I stopped using deodorant permanently.

  8. Dr Patrick Neustatter

    I saw a young woman patient the other day with recurrent boils in her arm pits for just this reason – aggravated by the trauma of shaving. For some reason she wasn’t very accepting of my idea of letting the hair and the bacteria grow naturally in the arm pit/axilla!

  9. Laina
    Naples FL USA

    When I was barely old enough to need deodorant, the XXXX stuff was out and that is what my mother bought. I got 2 nasty painful boils under my arms, and never had one before or since anywhere. I figured that it was the deodorant. (aluminum chlorhydrate??) must work by stopping up pores. I did ‘treatment’ on them myself…and my mother did buy Mitchum’s for me. But took awhile for ‘self surgery’ to heal.

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