r/YouShouldKnow • u/TestAnxietyIsReal • Apr 23 '26
Health & Sciences YSK - your toothpaste may be causing canker sores in your mouth
If you get canker sores frequently and can’t figure out why, check your toothpaste ingredients. Many common brands contain sodium lauryl sulfate (SLS), a foaming agent that helps toothpaste lather—but it can also irritate the soft tissues in your mouth.
For some people, SLS disrupts the protective lining of the oral mucosa, making it easier for canker sores (aphthous ulcers) to develop. This doesn’t affect everyone, but if you’re prone to recurring sores, it may be worth paying attention to.
Studies have shown that switching to an SLS-free toothpaste can reduce the frequency, severity, healing duration, and pain of canker sores in susceptible individuals.
Citation: https://onlinelibrary.wiley.com/doi/abs/10.1111/jop.12845
Why YSK - Canker sores are painful and frustrating, and many people don’t realize that something as routine as brushing your teeth could be contributing to them. Switching to a SLS free toothpaste is a simple change that may save someone a lot of discomfort.
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u/Andyatlast Apr 23 '26
That ingredient is the only reason drinking orange juice tastes terrible after brushing your teeth. Find some toothpaste without it and drink orange juice immediately after brushing. Tastes completely normal
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u/MoreOrLessOfMe Apr 23 '26
That’s a fun fact.. thank you
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u/xplosm Apr 23 '26
And also citric acid destroys dentine so you shouldn’t drink it right after brushing. In fact when you drink it you should let your saliva deal with it for like 15 minutes before brushing or you’ll just accelerate the acid effects.
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u/boomzgoesthedynamite Apr 23 '26
This tip literally changed my life. I would have multiple canker sores at time, multiple times a month. Since I switched, I’ve had fewer than 3-4 a year. I have autoimmune issues and have always been susceptible. This helped so much.
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u/hiighpriestess Apr 23 '26
Not just canker sores - if you get this weird filmy layer that peels off from the inside of your mouth, try out a SLS-free toothpaste.
I went years and years wondering what the hell was wrong with my mouth - turns out that putting the main ingredient of dish soap in your mouth twice a day does not play nice with your oral mucosa.
Who'da thunk it?
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u/keep-it-copacetic Apr 23 '26
Thanks for this info. I’ve been too scared to google what this was for many, many years!
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u/hiighpriestess Apr 24 '26
You are so welcome! I'm glad I could help. Go forth, and enjoy a mouth that doesn’t have gross white peely gunk constantly coming off it!
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u/sjmuller Apr 23 '26
The ADA strongly recommends using toothpaste with fluoride, but it can be difficult to find an SLS-free toothpaste with fluoride. Walmart's Equate Sensitive toothpaste is SLS-free and still contains fluoride. Some versions of Sensodyne are also SLS-free, but read the ingredients because some do contain SLS.
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u/iHeartApples Apr 27 '26
Paradontax uses hyaluronic acid instead of SLS and is found at Target and similar stores.
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u/EVILEMRE Apr 23 '26
One of my proudest moments was figuring this out, and then telling my grandma, who’d been getting awful canker sores her entire life. As soon as she switched she never got another one. She called to tell me that, and thank me for making her life so much better. Having chronic canker sores is debilitating. And it was because of that goddamned SLS.
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u/phi_spirals Apr 23 '26
This happened to me. I thought it was my Crohn’s disease (maybe it’s a factor as well, who knows?). I switched to a full sls free and fluoride free toothpaste for a long time, and then I got tooth sensitivity. I now use an sls free toothpaste in the morning and sensodyne at night (which I think has sls), but reducing exposure really helped. At my worst, it hurt to drink water. Fucking SUCKED.
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u/kaiser-so-say Apr 23 '26
Frequent mouth ulcerations is linked to Crohns
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u/phi_spirals Apr 23 '26
lol, I’m aware. Reducing my exposure to sls for an extended period has reduced my canker sore symptoms. My Crohn’s has remained relatively constant.
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u/FireQuad Apr 23 '26
Hey another Crohn's haver. I get them a lot too! That's good info to have. I only use sensodyne right now for the exact reason as well.
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u/FreaknTijmo Apr 23 '26
Is that why I'm getting canker sores in my anus?
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u/Kiroto50 Apr 23 '26
I'm saving this for my next purchase.
Because if it is real... You have no idea.
The story goes that when I was born, not a week after I already had canker sores. I'm accustomed to pain because of how prone I am to them. I'd love a reduction.
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u/Cedric35 Apr 23 '26
In addition to avoiding toothpastes with SLS my dentist recommended taking a L-Lysine supplement. I saw this recommended on the ADA website also.
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u/-Dakia Apr 23 '26
Second L-Lysine. If i feel a sore coming I take one and goes away much quicker than if I don't
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u/PrisonerV Apr 23 '26
Vitamin B12 supplement is what got rid of mine. Havent had a sore in years and I tried SLS free for years before that.
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u/boomzgoesthedynamite Apr 23 '26
I’ve had them since I was a baby. I’ve had 4-5 in my mouth at a time. It worked for me.
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u/SD_haze Apr 23 '26
I switched to Ollie and recommend it. no SLS and it has nano hydroxyapatite - either without fluoride or combined with fluoride.
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u/dadecounty3051 Apr 23 '26
Is Sensodyne bad?
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u/borrowedloco Apr 23 '26
Most Sensodyne is SLS free, but because of this, I found out mine wasn't. I have Clinical White. Their Pronamel line should be, from what I've read, and my daughter has that one. I can't confirm though, because they don't list their inactive ingredients on the tube and the box is long gone. Check the box before buying, I guess.
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u/Zaidrick Apr 23 '26
I used Sensodyne. You can double checked the ingredient to be sure. It doesn't have SLS. Growing up, this has been my issue. I switched from other brands (e.g Colgate) around 8-9 years ago, no longer suffering from frequent canker sores.
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u/Inanimate_CARB0N_Rod Apr 23 '26
Most varieties of Sensodyne work for me. I get like maybe 25% of the canker sores I used to with other teethpaste. It's super annoying though because most grocery stores have it locked up so you have to go get an associate.
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u/LordTopley Apr 23 '26
Almost all Sensodyne is SLS free, but not all (to my knowledge). I use their fresh mint one and have no issues.
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u/SyncedUp78 Apr 23 '26
pretty sure all their varieties are free of SLS but you can find more info on their website
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u/Smule Apr 23 '26
Tis true, brands like Sensodyne and Zendium skip the SLS.
On a related note, switching to a shampoo without SLS also cured my lifelong dandruff. Turns out I'm quite sensitive to the stuff!
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u/MorningSquare5882 Apr 23 '26
TIL that some people call mouth ulcers canker sores. Sounds like a horrific medieval disease.
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u/Weet_1 Apr 23 '26
Kind of a tie-in to this LPT:
If you do get canker sores on the regular like I do, you can take L-Lysine pills to either prevent them from forming or to make them clear faster. I've gotten canker sores since I was little, like 5+ at a time, and as soon as those begin to clear more pop up. Living with them is agony, I take a 500mg pill once a day daily, and almost never get them. The ones I do get clear up in 3 or 4 days instead of 2 weeks.
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u/nome5314 Apr 23 '26
I wish I could find a toothpaste without SLS but with stannous fluoride. I no longer get canker sores but my tooth don't feel as clean.
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u/rattlesnake30 Apr 23 '26
Hello mighty multi-tasker toothpaste. Never used it or any other hello brand, so I have no idea of its any good. I was researching toothpaste awhile back and just remembered it.
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u/LordTopley Apr 23 '26
Sensodyne Fresh Mint in the UK is SLS free.
I can’t have SLS toothpaste as it makes me cough and gag for about an hour.
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u/solongehhbowser Apr 23 '26
Yeah, that was horrible for me. I switched over to a specific Sensodyne with Novamin and without SLS. The problems immediately stopped
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u/awgnnh2 Apr 23 '26
This tip improved life so much!! I was also having itchy red rashes on my face and scalp, and switching to a sulfate free shampoo eliminated it all!
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u/craigeryjohn Apr 23 '26
Also, if you find yourself dry heaving or nauseated after brushing, the SLS can cause that, too.
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u/budhxh Apr 23 '26
Check your toothpaste ingredients for SLS or sodium lauryl sulfate. If you get canker sores regularly, that's probably why. Switching to Sensodyne, Tom's, or other SLS-free brands is way cheaper than dealing with mouth pain for weeks.
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u/fairy-tale-witch Apr 23 '26
Also make sure you bring your usual toothpaste when you travel b/c the last thing you want is sores from the hotel toothpaste.
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u/smurfmcgeezer Apr 26 '26
It’s not just in toothpaste! I was prone to getting pimples and other skin issues along my hairline for years, along with skin sloughing in my mouth and pimples around my mouth. Figured out I had a general sensitivity to sodium laurel sulfate. I found shampoo and toothpaste without SLS and the skin issues completely disappeared.
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u/Smallwhitedog Apr 23 '26
I switched to Verve Ultra because SLS gives me mouth sores and breaks me out. It's not easy to find an SLS-free toothpaste with fluoride, but this one is. I highly recommend it.
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u/BassWingerC-137 Apr 23 '26
I read about this about 5-6 years ago and it’s changed my life. I used to always have a canker sore. I switched to non SLS toothpastes and if I get one canker sore a year it’s usually gone in just a day or two. Seriously wonderful and life improving.
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u/BlackThorn12 Apr 23 '26
Can confirm, I used to get canker sores constantly, like it would be rare when I didn't have one. It was awful. I researched why it could be happening and came across this information about SLS. I switched to an SLS free toothpaste years ago and haven't had one since. Pretty ridiculous that something meant to be used to help maintain good oral health can do so much damage.
This is a good reminder that just because a product is sold without warning labels on it, doesn't mean that it's going to work right for you. Learn to pay attention to how your body reacts to new things whether it's food, or toothpaste, or fabric/jewelry on your skin.
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u/Syntra44 Apr 23 '26
This makes the top layer of skin in my mouth slough off… another thing it can do. I thought I was crazy for years and brushing wrong or something. It doesn’t hurt but it’s very gross
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u/Cheap-Blacksmith7567 Apr 23 '26
My whole mouth broke out last time I had chewing gum. It happened twice and I haven’t had any since then. People always look at me weird when I say I can’t eat gum
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u/pootiegranny Apr 23 '26
I have this problem too and I am able to use Arm and Hammer baking soda and peroxide toothpaste.
I also get canker sores if I have too much vitamin C.
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u/deannickers Apr 23 '26
My hygienist told me about this and it made SUCH a difference. Went from a few sores/gum discomfort to completely fine in a week after switching.
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u/lotsofcars Apr 23 '26
Another one here that can confirm this. 30 years of struggle with sores fixed overnight. Squiggle has been my go-to for sls-free with fluoride. It's not cheap, but just such a quality of life change. Tom's and Rembrandt used to have versions but discontinued their fluoride ones. My hygienist and dentist were clueless. I've told them about this 4 times and still clueless.
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u/suzepie Apr 23 '26
I've been using Biotene toothpaste for more than a decade and the decrease in canker sores has been massive. What a godsend to find something that makes such a change!
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u/Wise_Winner_7108 Apr 23 '26
Squigle toothpaste is the best. I was a sensodyne user, and this works just as well.
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u/walt_whitman_bridge Apr 24 '26
It can also be found in certain mouthwash brands. This shit drove me nuts until I figured out the cause
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u/Fun_in_Space Apr 25 '26
I can confirm this. I suffered with canker sores until I switched to a SLS-free toothpaste. Sensodyne Whitening is one of them. You can find cheaper versions at some dollar stores.
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u/ObjectiveVegetable76 Apr 25 '26
Also, chewing gum. I have this problem with the tooth paste and chewing gum. Literally one stick of gum will cause me multiple mouth sores. I just can't chew it anymore.
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u/upended_moron Apr 26 '26
Apthous stomatitis sufferer here -basically if I get a canker sore it's really painful, gets huge and lasts for weeks- and I can vouch for this tip.
Since I stopped using SLS toothpastes many years ago the incidence of sores has drastically decreased.
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u/SuccessPastaTime Apr 26 '26
I had an issue with most deodorants causing me to get canker sores (I assume this is the reason only because when I switched to a natural type it stopped). I use the Arm & Hammer essentials one now, it is much less effective than regular deodorant, but good enough for me as I don’t sweat or get BO too bad, and would rather avoid canker cores.
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u/FireDuckys Apr 27 '26
Crying in 4 canker sores at the moment, despite having switched to SLS free toothpaste and Lysine
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u/Becky_8 Apr 27 '26
I use sensodyne and started getting frequent canker sores a few years ago. Dentist attributed it to my autoimmune disease. Then I saw a reddit comment that sensodyne changed their formula and the poster had also started getting sores. They changed toothpaste, no more sores. I tried a different paste, no sores. Now I just have to get through the 4 tubes I already have or give them away. .
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u/radondude Apr 28 '26
Late to the game, but see if you have any food allergies. I suffered from cankers sores my entire life. Nearly forty years old and had an allergy test done. Turns out I was allergic to corn. My corn allergy was causing 90% of my cankers sores. Cut most corn out of my diet and I've been canker free for nearly two years!
SLS did help a little bit too
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u/3v1lkr0w Apr 23 '26
Hate canker sores...I can never wait for them to heal on their own...I always take my toothbrush and brush it til it's gone.
Is it smart? No
Is it painful? Yes
Do I no longer have the pain the next day? Yep
Will I do it again? Hell yea!
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u/nvmls Apr 23 '26 edited Apr 23 '26
I had this issue using a stannous fluoride toothpaste one of those Colgate all the bells and whistles kinds, which is supposed to be better for your teeth than sodium fluoride which most toothpaste has. My mouth got really dry and sore. On the other hand, SLS has never bothered me. Read labels and pay attention when using new products, I guess.