“Hey kiddo, do any of your books have a picture of a flamingo that looks like a question mark?”

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“I don’t think so…oh yeah, my dictionary!”

It’s not a huge dictionary, but it’s not a small one, so I am equal parts awed and scared.

Deodorant sits at the intersection of snackHQ’s hot topics. Why are we conditioned to think of regular human emissions as unacceptable? Why are pseudoscientific claims linking a product to cancer so compelling? Why do we all use the word “deodorant” when we really mean “antiperspirant”?

I’m not answering any of these questions today, because I need an answer to a much smaller one: why did my deodorant turn pink?

Our family’s mantra this year has been

Use what we have
Replace with care

which means that in August, I opened a closet full of abandoned tubes and bottles, like that toothpaste I didn’t love the taste of or the cache of runners-up in my years-ago deodorant test.

When I turned two clicks’ worth of Mitchum Advanced Control Shower Fresh, little bubbles of pinkish liquid came up. The pink varied throughout the product, but it was brighter than bubblegum and lighter than watermelon. Think flamingo or shrimp pink. It still smells the same as the first time I stopped using it, which may indicate why I’d forgotten it in a moving box to begin with even if I hadn’t remembered the burns that meant long sleeves for a week. It wasn’t so much gel as it was spill-over-the-side-of-the-container watery. There was no expiration date on this product, but it’s clear it hasn’t aged well.

Sure, I could have tossed the stick and resolved to do less bulk-shopping…just as soon as we’re done with our toothpaste taste test. But I was curious. Why did it turn pink?

I started by googling “deodorant turned pink,” and to my delight, the question has been asked more than once on Yahoo Answers, which is perhaps not the best place to find an actual answer but a great place if you’re a trio of brothers looking for material for your comedy podcast. The answer was as clear as my deodorant was not.

Internet Answer #1: Dye

The most common answer is that the deodorant user had recently worn a red shirt, a reasonable enough theory because if it can stain your laundry, it can probably stain your deodorant.

This answer failed to satisfy me because as a pale redhead, red is at the bottom of my clothing choices, only just above pink. I generally avoid red, save for one sleeveless dress and a long-sleeved race shirt I have never worn.

Others have suggested that armpit hair dye could be causing the problem, which I’m also confident wasn’t the cause in my case, because while I’d love to be the kind of woman brave enough to protest the patriarchy, I just can’t bring myself to put down the razor, let alone ombre-dye my pit hair.

I didn’t wear red and didn’t dye my armpits red, but there is one more way that I could have caused the dye stain myself: chromhidrosis. Although I did turn my toilet seat blue when pregnant, that may just have been because I was too lazy to launder new pregnancy jeans, so I think it’s safe to assume my body isn’t doing the dye-ing.

Internet Answer #2: Time

Another frequently-offered answer is time: deodorant turns red because you kept it too long and it expired. That’s the position offered by Amazon reviews of a similar product, and one complaint on Complaints Board, which I think could provide further material for the McElroys. (See, for example, Yahoo: The disappearance of section of comments.)

Tiny little crystals did fall out of the top when I opened this long-neglected tube, so we might be onto something here. The FDA does not require approval for deodorants because they are categorized as “cosmetics,” but they do require approval for antiperspirants because they are considered drugs. The FDA regulates what types of aluminum salts may be in antiperspirant and in what concentrations, as well as some fun rules about the claims a company can make about its effectiveness. For example, if you can demonstrate a 20% reduction in wetness you can claim a certain number of hours of effectiveness, which explains all those 48-hour deodorants on the market.

The main rule that applies to our question here is the FDA required expiration date. Because it is a drug, an antiperspirant must have an expiration date, and the industry-wide date appears to be three years.

What, exactly, happens to an antiperspirant during that time? One internet-offered idea is that the aluminum rusts, which makes sense because aluminum gets blamed for everything else in antiperspirant, but makes less sense because aluminum does not rust, because aluminum is not iron, and another word for rust is iron oxide.

Another internet-offered theory is that there’s some kind of lethal bacterial contamination, which seems at odds with the function of antiperspirants, which are generally marketed as antiperspirant-deodorants specifically formulated to inhibit bacterial growth.

Company Answer: Throw it Out and Buy Some More

These first two answers weren’t particularly satisfying, so I emailed the company directly:


After a year spent misplaced in a moving box, my stick of Advanced Control Shower Fresh turned pink. A quick bit of Googling turned up some farfetched explanations (the user must have worn a red shirt, the pink indicates life-threatening bacteria, etc.), none of which seem accurate. I would like to set the record straight on snackdinner.com, where I teach parents who to be better researchers.

My assumption is that prolonged exposure to air causes the pink hue, but could you offer a more specific scientific explanation as to what’s going on, as well as advice about whether or not to discontinue using antiperspirants that have turned pink?

Thank you,

I actually emailed twice, because Mitchum’s Q&A page does not include a confirmation screen, which is why a few weeks later I received two letters from the Revlon corporation. The first was from Melinda, who thanked me for my comments and who was “indeed sorry to learn of the experience you attribute to Mitchum Women Advanced Gel Shower Fresh Anti-Perspirant and Deodorant, but are glad to have the opportunity to assist you.” She also gave me two $5 gift certificates “as a gesture of goodwill.”

The second came from Phyllis, who also thanked me for my recent comments and was “indeed sorry to learn of the experience you attribute to Mitchum Advanced Control Invisible Solid Shower Fresh Anti-Perspirant and Deodorant, but are glad to have the opportunity to assist you” and enclosing a $5 gift certificate “as a gesture of goodwill.”

Why did Melinda give me more money for my trouble? Was it her status as a “Manager” to Phyllis’ “Consumer Information Representative”? Or does selecting a particular product from the complaint list automatically suggest the proper compensation? These are questions for another time, because neither letter got me further to answering the pink deodorant question. They also did not help me restock my dwindling supply of deodorant, because they are in-store coupons and I’m not risking anyone’s health no matter how big the antiperspirant spree.

Internet Answer #3: Salt

When Yahoo Answers can’t answer your question and experts don’t appear to want to answer your question, what do you do? At times like these, it helps to zoom out a bit and ask What other things turn flamingo-pink? Might those explanations apply to the antiperspirant/deodorant question?

Lakes can turn pink under the right conditions, which includes warm and dry weather that leads to evaporation, which leads to increased salinity, which makes the lake hostile to most organisms but hospitable to algae that like to feast on Halobacterium salinarum, which, despite the name, is a salt-loving not-bacteria that I will leave you to research on your own.

Was my antiperspirant like a high-salinity lake? The salt in my particular tube was at a higher concentration than many other aluminum salts (aluminum sequichlorohydrate 25%). Could warm and dry conditions (or just time) have led to evaporation that led to even higher salinity, that led to a happy environment for some tiny pink organism?

Expert Spouse Answer: Bacteria

I mentioned the salt lake-deodorant comparison to my husband, who responded “that sounds like Serratia marascens.” We thought “marascens” referred to its red color, which once enthralled religious devotees who observed bleeding statues and bread and which now will make me think differently about my next cocktail cherry, but that’s only because we were misspelling the name. The actual bacteria is called Serratia marcescens, which comes from the Latin for “decay,” and reassures me that discarding my pinkening antiperspirant was the right choice.

Serratia marcescens can cause conjunctivitis, pneumonia, urinary tract infections, and the pink ring around your shower drain. My husband suggested that the best way to find out whether or not it could also grow on antiperspirant would be to ask how people try to get it to grow on purpose. He sent me this review of MacConkey Agar, which “is used for the isolation and differentiation of non-fastidious gram-negative rods,” which I understand to mean that it is not particularly concerned with cleanliness, which makes it all the more fitting that the Cat in the Hat should take it up as a sequel subject. [“Pink ring” is perhaps not the most accurate description, but we can’t fault Seuss that Serratia marcescens wasn’t on his word list, and also because when Seuss was writing that book, the US Navy was stealth-spraying the San Franciso shoreline with what it thought was harmless Serratia marcescens to test the spread of bacteria. The resulting increase in pneumonia and other infections is how we learned that the bacteria can be harmful.]

I did recognize a few words, like enteric, which means that MacConkey Agar is good for culturing bacteria that thrive in the intestines. Serratia marcescens might not be as famous as the name-brand enteric bacteria like E. coli and Salmonella, but they all live in the same neighborhood. While unpleasant to think about, it’s not surprising that antiperspirant—which tends to live in bathrooms—could come into contact with intestinal bacteria, which also tends to live in bathrooms.

So how does the antiperspirant compare to MacConkkey’s agar? There are at least two sugars listed on the label—xylitol and glycerin—and at least one salt (the active ingredient is an aluminum salt). A gel antiperspirant is pretty damp, and even if it wasn’t it would be routinely opened in a steamy bathroom. You could hypothesize that an antiperspirant could provide just the right conditions for Serratia marcescens to grow even if you didn’t know that they are notoriously soap-philic.

Your Answer: Forthcoming

The lesson, perhaps, is never to ask the internet a question before asking your spouse, especially if that spouse has studied any amount of graduate-level microbiology. But six weeks into this question, I still can’t know for sure what happened, which is why I need your help. If you’re a snackdinner reader and a microbiologist, or a snackdinner reader and a chemist, or you’re a snackdinner reader with a microscope and a tube of pinkening deodorant, you can help answer this question for us.

That’s why I’m going to do a very scary thing for bloggers to do and turn on the comments. I will leave them on until the third pinksplanation or the third troll, whichever comes first.

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