Canker Sores
Natural Remedies

Alum for Canker Sores

46 User Reviews

5 star (38) 
3 star (2) 
1 star (2) 

Posted by John (Lake Oswego, Oregon) on 01/19/2012
5 out of 5 stars

I've been using alum on canker sores as a cure for 30 years and wouldn't use anything else. My whole family uses it.

Posted by Mariana (Roseville, Minnesota) on 12/22/2011
5 out of 5 stars

I was surprised to find alum missing from your list of remedies. It would be interesting to see what other folks use this for. It's great for treating canker sores. They go away almost instantly. My mother used this for us when we were kids, and her mother used it too. I think it's a pretty ancient substance that was used widely in the Middle East and Africa. We use the powdered kind that is sold in grocery stores. (It's used in pickling, for crispness. )

Anyhow, what we do to treat a cankersore is merely moisten a Q-tip, and dip it in a very small amount of alum mixed with a teaspoon of warm water. After the alum is on for a few minutes, just rinse your mouth because the alum is very bitter. People also use alum as a mouthwash and to treat gum disease or aching teeth. It's used to treat eczema itching, and styes as well. I'm sure the solution would need to be much milder for use on the eyes, or as a mouthwash, or in treating eczema. Anyway, I hope others might want to mention their experiences with using this common household ingredient. Mariana

Replied by Robert Henry
(Ten Mile, Tn Usa)

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=============

Replied by Susan
(San Francisco, Ca)

My grandmother taught me this when I was a kid (I'm 57). I've tried other remedies and the Alum has always been the cure that worked fastest for me.

Replied by Jessica
(Waconia, Minnesota)
5 out of 5 stars

I use Alum for cold sores and canker sores too! It is utterly amazing how fast they disappear with just a couple applications. I refuse to spend money on anything else. Cheapest most effective treatment out there! I tell everyone about it when I can!

Replied by Maria
(Gippsland, Australia)

Could someone please tell me what is the Alum that is often refered to here? I have done a search and found that it can be either potassium alum, soda alum (used in baking powder), ferric alum or ammonium alum. Thanks.

Replied by Didi
(Dover, Usa)

Alum is a salty substance used in Pickeling or a brine. You can get it in the spice section of the grocery store.

Replied by Maria
(Gippsland, Australia)

Thanks Didi for that. I have never seen it here (Australia) but maybe it is sold under another name and not the name Alum.

Replied by Derek
(Austin, Mn)

The Alum referred to here is Ammonium-type Alum. I've got an ancient container of Schilling Alum. On the container it reads, "Powdered Alum (Ammonium)".

Posted by Jennifer (Midland, Michigan) on 09/15/2011
5 out of 5 stars

Alum DOES work! My mother has an old jar of crystallized Alum that she has used on all our canker sores forever. I take a piece and set it on the canker sore for several minutes. It not only relieves the pain, but shrinks it and makes it disappear within a day or two. I still use it and use it on my kids now. It does not taste great, but it is worth the results it gives you. Hip, Hip Horray for Alum!!

Posted by Mikayla (Toronto, On, Canada) on 08/26/2011
5 out of 5 stars

Wow, alum works!

I never get canker sores, but a few days ago, I got itchy red hives on my torso as well as 6 canker sores under my tongue and my cheeks. I've had several surgeries but have never been in such pain in my life! So bizarre that such a little thing can cause so much discomfort.

Anyway, after reading the comments, I tried Alum and so far it's amazing. It has really numbed the canker sores. I can eat!!

My only caution is because it does numb so well, be aware not to bite your cheek accidently. I did that and another canker sore developed; but the overall relief is so worth it.

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 Kimkat (Hingham, Ma) on 04/27/2011
3 out of 5 stars

Better But With Side Effects

Alum for canker sores - I just applied to 4 cankers in my mouth and the smaller cankers on inside of lips felt a sting and then a little better instantly, achy but a little better---- BUT the almost centimeter size one on tongue- GOD HELP ME THE PAIN IS INTENSE. I couldn't keep the alum on for long for that one, 30 seconds and almost passed out. BUT I will try again~ I drooled like a fool but been doing that all day. I have eaten NOTHING today the pain got so bad and that is with double dose ibuprofen on board for 3 days. Anyone had luck with this stuff and large cankers of the tongue??

I might have to call my doctor for painkillers - this is almost unbearable (yes I have a low threshhold for pain)

Replied by Sfcb1
(San Francisco, Ca Usa)
1 out of 5 stars

It may be that I discovered this information too late, but I tried the alum solution repeatedly on my latest canker sore (haven't been able to talk or eat pain-free for 5 days now) and it seemed to make it a little worse. It certainly didn't help, although it wasn't as painful as some of the posts here warned it might be. I would have to vote Nay for this one.

Replied by Gilroy
(City, Us)

Alum isn't meant to be a pain reliever for canker sores. It is meant as a cautry agent so that they burn up and heal faster. It's not going to make the pain go away.

Posted by Bg (Lakewood, Oh) on 02/19/2011
5 out of 5 stars

I'm really prone to canker sores if I bite the inside of my lip, or if my diet becomes too acidic (too much coffee, caffeine, beer, fruits, chocolate, sweets, etc. )

I used to use a prescription paste which I haven't been able to get out here (Kenalog in Orabase? I think) which worked wonders and would quite literally get rid of my sores overnight. Since I've been unable to get that prescription filled, I needed a different remedy, so I went with alum. My only quip with alum is that it tastes NAAAAASTY. Seriously, if you swallow it, you will probably vomit. Bitter, awful, disgusting taste--BUT it works like a dream on canker sores and dries them out after a few applications. I usually daub a bit on the sore with a wet Q-tip, then let it sit there and dry for about five minutes before rinsing out my mouth and/or brushing my teeth (because the taste just sticks to your tongue). The more stubborn sores still take a few days to go away, but the alum seems to alleviate the pain and bring down the swelling and the size of the sore almost immediately. I highly recommend this remedy -- just remember not to swallow or spit it out before your five minutes are up.

Posted by Pcheeks (Washington, Dc, Usa) on 06/01/2010
5 out of 5 stars

I have always had problems with canker sores. I usually just wait it out or apply some numbing gel. This time I got one on my tongue. It was sooo painful and wouldn't go away. I found this website and tried alum. It really really burned the first time I used it. To the point of tears but after 3-4 applications (48 hours) it was gone! I definitely recommend this.

Posted by Dave (Austin, Tx) on 11/30/2009
5 out of 5 stars

Alum for fever blister/cold sore/canker sore

Thought I might help those of you who are suffering with cold sores etc. As a child I 'suffered' with this malady on occassion. When ever it happened, I would tell my mom and she would immediately reach into the kitchen spices for the alum. This is the new information which I have not seen on any site thus far. Before using the alum mom would put a small amount on a disposable piece of metal (usually the top removed from a can of vegetables) and heat the alum to the point where all the moisture is driven from the alum powder. At this point the alum will crystallize on the can lid (This is what I learned to call burnt alum). Allow to cool. Once the crystallized alum has cooled, take a spoon and crush the burnt alum and apply as described elsewhere. As mentioned alum is an astringent, and the value of this process is to improve the astingent properties of the alum. As with those who have used this remedy regularly, I also had complete relief within two days.

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.

Replied by Splendor
(Chandler, Az)

I have the alum on my canker sores now, so we'll see. But last night I placed an asprin pill on each of the 2 cankers that I have in my mouth; seriously just hold it on top of the sore, between your cheek and gum until it just begins to dissolve, then spit it out and rinse. This totally numbs it for like 12 hours, then apply the alum because it barely stings at all. Hope the alum does the trick! :o)

Posted by Kathleen (Newport Beach, Ca) on 10/09/2009
0 out of 5 stars

Ok! When I'm stressed I bite the inside of my mouth. Yuck!! I know! This can lead to the MOTHER of all canker sores. My dear friend just told me to dab alum into the canker sore, hold the affected area out so it can settle into canker sore and not be washed away by saliva. Let me explain. What I have going is a flipping cluster of sores( 12 in total. SERIOUSLY!!) A few are about 1/4 x 3/8. No I'm not joking. So I apply the alum out of desperation. I'm in constant pain, my lips aren't working. Drool is running down my chin(SEXY right?) AND i CAN'T eat. Ok the alum feels like flipping battery ACID. I want to rip half my face off. Who cares that it tastes viley bitter-it REALLY hurts. It does not sting. Serious PAIN. After about 20 minutes half my lower jaw is numb. Thank God!!! It feels a little swollen. I look in the mirror and honest to God it looks like I've just had half of my mouth pumped up with whatever that crap is that make you look like a freak of nature! I live in newport beach-the land of the plastic fantastic. Please tell me that this will subside and I won't look like a middle aged woman having a midlife crisis and a budget to only cover half the job! Frickin' Y-I-K-E-S !!!!!!!!

Replied by Man0fsteel
(Redondo Beach, Ca, USA)
0 out of 5 stars

Okay, so I get canker sores every so often, esp. when I don't get enough sleep. This particular monster sore on my lower lip started when I severely bit into my lower lip TWICE on the same spot a week ago. No signs of healing. And they usually do after a week. Not this one. So someone suggested Alum. A quick search online brings me here where there is a lot of positive feedback. So I put the Alum on and like the above post, the pain is pretty intense. Tears are leaking involuntarily out of my eyes. 5 minutes go by and I rinse it off. It's now about 30 min after and the sore feels like it's twice the previous size. Totally swollen. And it's throbbing like no tomorrow. If it gets better, I'll be shocked, but I will report if it does in the morning.

Replied by Alice
(Shingle Springs, Ca, U.S.A.)

Smashing up a lysine (a particular amino acid) tab and making a paste with water and applying it to the sore is reported to relieve it. Totally non-toxic.

Posted by Ben (Rochester, NY) on 01/30/2009
5 out of 5 stars

Yes to Using Alum found at the grocery store in the spices section. I read the comments about canker sores on here. Thank God for nice people! Apply it with a wet Q-tip on Sore. It will sting but the after effects are worth it! Thanksabunch

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:

Replied by Chris
(St louis, MO)

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.

Replied by Dan
(Grand Rapids, MI)

The reason alum works is that it is an astringent, not because it forces anything into your body.

Posted by Saskia (Takoma Park, MD, USA) on 10/06/2008
5 out of 5 stars

I had started taking apple cider vinegar twice a day, and after two days noticed the beginning of a canker sore. It didn't hurt yet, so I checked this site, then went out and got some Alum in the grocery store. I did as someone else suggested and wetted my finger, then dipped it into the alum, and then held it on the canker sore for about 5 minutes. Because I caught my canker sore so early, it didn't really sting at all.

I did that twice the first day, and again twice on the second day. It never hurt at all, and it got a little larger at first, but then started receding, and now 4 days later, its basically gone! I'm so happy with the Alum cure! I used to spend a whole week in agony thinking there was no way to help it- I love this website!

Posted by Cblhris (Bloomington, IN) on 08/09/2008
5 out of 5 stars

I am apparently one of those peoplt that are particularly susceptible to canker sores. I have tried many remedies, but the best by far is the alum. It stings a bit of first, but after one application the canker sore pain is gone. After two, the lesion is gone. Having used it dozens of times, I can say that if you don't mind the sting, alum is the only way to go!!

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