Canker Sores
Natural Remedies

Alum for Canker Sores

| Modified on Jan 18, 2023
Posted by Stacy (New Haven, Ct) on 07/21/2017
5 out of 5 stars

I have been using Earth Clinic for natural remedies for a few years now, but this is my first review because it's the one remedy that works EVERY single time. Sometimes I think, this canker sore is TOO painful or TOO big for this remedy to work, but it absolutely does.

Is there ANYTHING worse than trying to chew on one side of your mouth to avoid irritating a canker sore? Anything worse than avoiding your favorite foods/drinks as to not make the pain worse?? I love salty snacks, love my coffee and salt & vinegar chips, so I'm definitely prone to cankers sores every couple months.

My method is as follows:

Dip the end of a Q-tip into a bit of raw honey, just enough to coat the tip. Then dip the honey end into the alum. For this next part, I find it best to use one hand to hold my iPhone with the flashlight on to light up the inside of my mouth so I can see what I'm doing. With the other hand, place the Q-tip on the canker sore to coat it. Don't swallow for 1 minute. I do this in front of the bathroom sink because sometimes you do drool! Then I rinse my mouth with water, go to sleep, and by the morning it's painless and much smaller, if not completely gone.

Sometimes the after taste of the alum can leave your mouth feeling funny and dry, but drinking water definitely helps.

Thanks to to all who have suggested this amazing remedy! My mouth thanks you! :)

Posted by Twinkytoze (Brampton On) on 06/18/2017
5 out of 5 stars

Alum, worked a charm. A big fat white canker visibly bulging out my lower lip was reduced overnight to a pin dot. Pain and irritation gone. Going to hit it again tonight before bed just for good measure.

Posted by Daisy (San Francisco, Ca) on 08/05/2011
5 out of 5 stars

I've suffered from canker sores since I was six years old and have literally tried EVERYTHING... Over-the-counter, prescriptions. I've even dipped a Q-tip in fingernail polish remover and applied that directly to the sore. (Probably hazardous, I know, but after the insane stinging went away, it actually numbed the sore for quite a while.)

I had a canker sore on my tongue for three days that was hurting so much, I couldn't eat or talk. I stumbled upon this thread in my google search for remedies and this was the first time I'd ever heard of alum.

I went to the grocery store, picked some up (in the spice aisle) and went straight home. I dipped a wet Q-tip in the alum and applied it directly to the sore on my tongue. Yes, it stung, but not horrendously (and certainly not as bad as fingernail polish remover --- cannot believe I admitted I did that). There was some drool and whatnot, and fifteen minute later my tongue was throbbing.

I dissolved an asprin directly onto my tongue and SERIOUSLY? THE PAIN ALMOST COMPLETELY WENT AWAY.

I woke up this morning and while the sore is still there, and even bigger, IT DOESN'T HURT.

After dealing with intensely painful canker sores for almost 30 years, I cannot even begin to tell you how happy this makes me. I feel like alum is going to change my life for the better. I know this sounds ridiculous, but one bad canker sore can seriously ruin your week.


Posted by Liz (Hudson Valley, New York) on 11/12/2009
3 out of 5 stars

Better But With Side Effects

I had a canker sore that was at the peak of inflammation and pain and I decided to try putting Alum on it last night as recommended here to stop the pain. I bought the crystallized kind from the spice section of the grocery store and licked my finger, dabbed it it the alum and then dabbed it on the sore and let it sit/dry/sink in for 5 minutes.

OH MY GOD - it hurt like nobody's business which I could tolerate, but then for the next hour it made my entire jaw, neck and ear area throb with terrible pain which I could not tolerate. I ended up taking pain relievers and going to bed several hours early just to stop the pain with sleep. I have not been in such agonizing pain for many years. It felt like a migraine and an earache and a toothache all at once.

However, today my canker sore has been very tender but noticeably less painful (i've also been on pain meds all day because I'm a bit scarred by what happened last night). The sore also seems to be healing. I honestly am not sure if I can recommend the alum or not, given the positive effects today and the horrible effects last night.

Posted by Cb (San Diego, CA) on 05/26/2012
5 out of 5 stars

I have been suffering from canker sores for 15 years of my life. After biting my tongue in the same place twice for the thousandth time, I decided that was the last straw. I went online and found and tried the Alum solution. It's only been a couple of days but I have already started to see positive results. My sore got bigger and deeper but not as painful. Now it's almost completely gone. It definately helped to numb the pain especially when I dissolved the Tylenol right after. I would recommend this treatment.

Posted by Robert Henry (Ten Mile, Tn Usa ) on 12/23/2011

ALUM us Aluminum Sulfate, ole folks like me made the mistake of using it to make pickles and other canned goods, crisp. All we did is put Aluminum in our brains, which brings on dememtia. I don't have a clue about the use of alum on your skin. Do not use Alum for internal consumption. We all are savvy about transdermal therapy. What you put on your skin goes into your body. Why do you think the chelation clinics are full of auto mechanics who washed parts in leaded gasoline. Now they are trying to get the lead our of their body.

Good people there are lots of good intentioned folks posting on this site. Some just don't have a clue. Pay attention.

========ROBERT HENRY=============

Posted by Sid (Salmon Arm, BC, Canada) on 01/18/2009
1 out of 5 stars


Alum is a form of aluminum. Oral injestion of aluminum can cause canker sores. Do you really want to do that? The reason it works may be the same reason that the mercuric ointment my mom used to put on my rashes ( I later found out that I was mercury toxic) got rid of my rash. Apparently, it makes it go deeper into your body, thereby getting rid of the eruption on the surface.

EC: More about this here:

Posted by Chris (St louis, MO) on 02/14/2009

Alum has nothing to do with alumnium; how on earth do you labor under that delusion?

EC: Best answer we could find on the alum used in cooking:

"Alum is a salt that in chemistry is a combination of an alkali metal, such as sodium, potassium, or ammonium and a trivalent metal, such as aluminum, iron, or chromium. The most common form, potassium aluminum sulfate, or potash alum, is one form that has been used in food processing. Another, sodium aluminum sulfate, is an ingredient in commercially produced baking powder. (Have you never noticed the faint metallic taste in baking powder? It comes from the alum.)

The potassium-based alum has been used to produce crisp cucumber and watermelon-rind pickles as well as maraschino cherries, where the aluminum ions strengthen the fruits' cell-wall pectins.

Alum is approved by the U.S. Food and Drug Administration as a food additive, but in large quantities — well, an ounce or more — it is toxic to humans. As a result, efforts have been made and are being made to wean us of our alum dependency. The U.S. Department of Agriculture says that if good quality produce and modern canning methods are employed, there is no need to use alum to bolster the crispness of our pickles and cherries. In any event, t"he department says, even if alum is used to soak the pickles, it should not be used in the final pickling liquid.

Posted by Keny (Canada) on 09/19/2020
5 out of 5 stars

Alum hurts the least compared to many of the other top methods!

Why it works: It seals the wound.

It essentially dries the wound and causes it to contract, sealing the wound. You have to let it dry for it to be effective, this usually takes 2-3 minutes, but I'd give it more time to be sure (depends on your air).

It only hurts for the first 20-30 seconds, unlike other methods, and it seems to hurt less than salt/baking soda. It doesn't hurt long because the wound ends up sealed, so nothing that doesn't penetrate the seal will then hurt it!

If you use it while it is still SMALL it will hurt a lot less. I highly suggest using it when you see even the remote possibility of a canker sore. Let it dry, then rinse your mouth. Don't drink the alum, unless you're genetically allergic it probably won't kill you, but it's probably not good for you either.

The havoc of having an open wound in your mouth letting in all sorts of toxins and bacteria is likely way worse than any effect you can get from slight contact with alum, which is used as a pickling ingredient. The exception is if you're deadly allergic to alum. You can test by putting pin pricking your skin very lightly with a sterilized needle and putting a little alum to see how you react to it (that is how allergies are tested).

Posted by Miss T (NC ) on 08/31/2019
5 out of 5 stars

Alum does work for shortening the healing time of the canker sore. The article is spot on with the recommendations and warnings! I have used for years for myself and my family.

Posted by Lauren (Ny) on 02/22/2018
0 out of 5 stars

Be careful...the alum reacted negatively in my mouth and cause a more severe outbreak.

Posted by Patricia (Bucyrus, Mo) on 07/26/2016
5 out of 5 stars

Canker sores on the inside of your cheek, gum or tongue can be very painful. I have found a foolproof method to get rid of them overnight. Just get a jar of Alum, available in the Spice section of your supermarket, dampen your finger and place a good amount of the alum directly on the sore. Keep it there more than a minute. Then rinse your mouth several times with clear water. In the morning, the canker sore will be gone. I have also used this remedy for sores beginning on my lip. It has worked every time.

Posted by Josh (Weatherford) on 07/05/2015
5 out of 5 stars

I literally made an account just so I could share my experience with Alum powder. From what everyone else has been saying, they were on the verge of tears when using it. It is not that bad. I have a cluster of 8 canker sores, and I have NEVER had more than one at the same time. So this was a very odd experience for me to get EIGHT AT FREAKING ONCE. LITERALLY WOKE UP ONE MORNING AND THEY WERE ALL THERE. And yes, I chew at the inside of my lip whenever I'm nervous, anxious, etc. But I never learn. Anyways, I have 4 big ones, surrounded by 4 smaller ones. I used this alum powder on one of the littler ones, just to anticipate the pain so I wouldn't dive right into killing myself over a big one. I got a little bit of water on my fingertip, and then dipped it into the powder, got a fair amount, and then put it right on top of the sore. Yeah, it stung, pretty bad. But I use oral gel soft brush sticks to numb it, and it only hurt just a little bit more than that.

I set a timer on my phone for 2 minutes at first (I did this process twice for each sore), I never got to the point where I was on the verge of tears. My face got a little tingly, that was really it. But it's 10 minutes that I'm typing this after I went through this, and it still quite burns. But I'm only assuming that will go away within the next half hour(or maybe I missed a little tiny sore). After the first sore was taken care of, I got a large glob of it, and stuck it right in the center of alllllll of the sores. Yup. It hurt. But remember this when I say, you will never be able to get rid of a canker sore without pain, unless anesthesia is involved. I then set a timer for 2 and a half minutes, and waited it out. The sores definitely feel a little bit different when I touch around them with my tongue. They didn't burn AT ALL right when I rinsed with water, but only started burning again about a minute after. So that must be the side effects of the powder settling in deep in the sore. Which I also assume is a good thing? Kill that sore, alum. Kill it.

If you have any questions, feel free to ask away. I plan on doing this again tomorrow morning if the pain is still there (which I assume it will be, knowing my luck). So far, alum works!

Posted by Joecool025 (Sacramento, California) on 03/24/2015
5 out of 5 stars

Alum worked very well for me for canker sores. Here's what I did:

Bought a 2 ounce jar from the local grocer for about $5, which is more than enough. I bet 1/4 ounce would be plenty.

Over the bathroom sink, wet a q-tip, and dip it in the alum powder, roll it around to get a good amount on it. Then locate your canker sore and press and hold it on there real well. Time out 2 1/2 minutes on your watch or phone, then wet the other side of the q-tip, reapply, and repeat for another 2 1/2 minutes. Afterwards, rinse out that side of the mouth really well.

This stuff stings, and tastes bad. Try not to taste it with your tongue, and try not to swallow, just let the drool come out of your mouth down into the sink. It's not the most pleasant 5 minutes I've ever spent, but it really helped attack the sore, and minimized it, and dropped the pain down to about a 1 or 0 in 2 days.

I did this process twice a day for 2 days, and I am canker sore free!

Posted by Cb (Ny, US) on 10/23/2014
5 out of 5 stars

I waited until a month after I tried my remedy to write this post to make sure it didn't come back. I found out that I had gotten a muceole (cyst in mouth) from biting my lip and did EVERYTHING wrong. I tried to pop it like a pimple, I poked at it with a needle, ate hot/ spicy foods, and played with it with my tongue and teeth. Of course after two and a half weeks of having it, I learned what it is and everything I shouldn't do. I should say muceoles seem to expand and contract everyday or so - I thought a few times it was going away by itself, but it always came back until I tried this remedy.

Buy some Alum (a pickling agent, should be able to find it in the spice aisle) and some mouth wash (I don't think it matters but I used a antiseptic tartar control one). Using your finger or a cotton swab dab some (not much, maybe a pinch) of alum onto the muceole and leave it alone as long as you can keeping the area dry by holding your lip (or wherever) out of the wetness of your mouth. I did for a about 20 mins - then wash it out carefully. WARNING - alum does not taste good and will feel strange in your mouth. Then use the mouth wash. The alum should "dry up" the muceole and the mouth wash will keep it from getting infected or bigger.

The next day (I did the first time at night) I noticed where I had placed the alum had dried the skin, much of my mouth was dry with peeling skin (not as bad as it sounds). I repeated this process three times within a six hour period the day after I started the remedy. I recommend starting on a weekend so you have time to do this. At this point I could see the white spot within the muceole (salivary gland) which is a good sign. After that I used mouth wash consistently for three days and my muceole healed and completely went away. It's now been a month without it coming back. Hope this helps someone out there!

Posted by Edward (San Francisco, CA) on 09/05/2014
5 out of 5 stars

I'm 73 years old and have used the alum treatment for canker sores most of my life...My grandmother took powdered alum, heated the powder in a small pan till it melted. My mother took the heated (melt) powder and poured the stuff into a small piece of aluminum foil to make alum crystals. Then the crystals were put on the sore...After a few minutes the pink sores turned white, and without pain.

Posted by Katherine (Calgary, Alberta) on 06/24/2012
5 out of 5 stars

Alum works wonders! I bit my lip a couple days ago and usually the canker sores don't hurt all that much as I get them a lot. This time however it got so big so fast I couldn't eat or talk. I looked at this site and went over to the grocery store and bought some alum. I held it on the canker sore for 5 minutes and it hurt A LOT. However in a couple of hours it looked like half of it was gone. I put some on before bed and the next morning all the swelling is gone, and I can't even feel that it's there. I recommend this for everyone!

Posted by Andrea (Des Moines, Ia) on 01/29/2015
0 out of 5 stars

Hey I just started using Alum tonight, and it hurt really bad, I mean horribly. And it's still burning. Will it be better in the morning? Cause I'm freaking out cause my canker sores hurt so much worse when I put the alum on it.

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