a canker sore (aphthous ulcer), remedy for canker sores

Canker sores (aka aphthous ulcers) are one of life’s little mysteries. Experts estimate that roughly one out of five people put up with these painful mouth lesions. Some suffer more than others:

“My husband has canker sores in his mouth all the time. The specialists we have seen say it is not curable and he just has to live with them. We have tried many topical remedies plus some prescription drugs without benefit.

“He is not sleeping well because of the pain and desperately needs some relief. We enjoy reading the remedies you share and wonder if you might have some suggestions that could help us now.”

What Causes Canker Sores?

Oddly, scientists do not know the exact cause of canker sores. Citrus fruits, trauma to the mouth and weakened immunity have all been blamed for these painful mouth lesions. Some research suggests that nutritional deficiencies (B vitamins or iron) may be partially responsible in certain cases.

Although they normally last about a week to 10 days, some people are plagued by these sores for much longer periods of time. The pain and irritation can be so severe that eating solid food can be almost impossible.

Is Toothpaste Responsible?

Some readers believe that a foaming agent (SLS or sodium lauryl sulfate) found in many toothpastes contributes to the problem:

“My sister and daughter suffered from severe canker sores for years. My sister’s doctor told her to stop using toothpaste with SLS. Now, both my daughter and sister have very few outbreaks.”

Despite such a testimonial, research is equivocal regarding the benefits of using SLS-free toothpaste (Oral Diseases, Jan. 1999). One study found that people using a toothpaste without SLS got just as many canker sores (Shim et al, Oral Diseases, Oct. 2012). However, the sores healed more quickly with SLS-free toothpaste.

Could Sugar Be a Problem?

Others are convinced that sugar is the culprit and cutting back on cookies and candy is the answer. That certainly is healthful advice for anyone, canker sores or no.

No Nuts to You:

Some readers believe nuts trigger an attack:

“I also suffered from massive canker sores. I finally realized that five days after eating walnuts the cankers would appear. Now I never touch the nuts and no sores!”

Treating Mouth Ulcers at Home:


Many people believe the solution lies in the amino acid supplement L-lysine despite a lack of scientific evidence:

“I had troubles for years with canker sores. A friend told me to start talking L-lysine twice a day at the first sign of a canker sore. It stops canker sores from getting larger and heals them within a day or two.”

Sauerkraut Juice:

Although these home remedies have not been tested, some people report success with swishing their mouths with an ounce of sauerkraut juice in the morning and evening, then swallowing about a tablespoonful:

“It is an unusual cure for canker sores, but I had a recurring sore that went away overnight after the first use of sauerkraut juice. And, you can have wieners and kraut with the leftovers.”


Another option is buttermilk:

“My oldest son used to get canker sores a lot. My mother-in-law gave us the ultimate cure that worked overnight. Swish cultured buttermilk in the mouth and hold it for about a minute then spit it out. We don’t know why it works, but it does.”

Kiwi Fruit:

We have even heard that kiwi fruit helps:

“My husband got a canker sore on Thursday and we bought a few kiwis to try this cure. He ate one kiwi in the morning, and by the mid-afternoon the sore was dried up. A second kiwi wasn’t needed. Amazing.”

Baking Soda:

One reader shared this experience with a very old-fashioned remedy from generations back.

“I occasionally get a canker sore, especially if I’ve eaten too many sweets. For the past 75 years I’ve always gotten immediate relief within 24 hours by taking one tablespoon of baking soda with a glass of warm water, just like my grandmother taught me. One dose does the job.”

While we appreciate remedies passed down from grandmothers, this one is not appropriate for everyone. A tablespoon of baking soda contains a lot of sodium-too much for some people. The “dose” recommended on the box for heartburn is a half teaspoon of baking soda in a 4 oz. glass of water. We would suggest starting with a lower amount than a tablespoon to see if it helps heal the canker sore.

Since there is no standard medical cure for canker sores, we see no harm in trying an inexpensive home remedy. You’ll find many in our book, The People’s Pharmacy Quick & Handy Home Remedies.

Revised 5/18/2017

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  1. Berryman

    I suffered with canker sores for about 50 years. I believe it was one of the Peoples Pharmacy articles that featured L-Lysine. This is a cure for me, although it doesn’t react very quickly. If I feel one coming on, I take one 1000 unit capsules every 6 hours until it has passed. Alternatively, this is not a commercial and I have no connection to the company that manufactures it, I have found that applying some Carmex liberally will halt it in its tracks. I put it on the tip of my finger and hold it on the sore (inside my mouth) for about 30 seconds and repeat this process every couple hours and the sore will be gone in one day.

  2. Shirley
    Palm Beach Gardens, Florida

    I had a tongue sore and a sensitive gum area. Both went away when I did 10 to 20 minutes of oil pulling (swishing a TBLSP of coconut oil in ny mouth) daily. Spit it out in a paper cup and throw away, don’t swallow or put in drain.

    I also switched from toothpaste with sodium lauryl sulfate to a safe paste without chemicals from the health food store. Teeth are white and mouth tissues are free of problems.

  3. Ed

    Rinse with salt water several times a day. Clears it up in two or three days!

  4. Nikki
    New Mexico

    When I have a canker sore, I saturate a cotton ball with hydrogen peroxide and place it on the sore. The canker sore is gone within 24 hours.

  5. dzrlib

    I thought they were due to a virus and on the rare occasion that I get one, I put a little Vitamin C crystals on my tongue and apply it to the sore. Stings but is very effective.

  6. Patricia

    As a child when I had a canker sore my mother helped me take a tiny bit of Alum on a toothpick and place it directly on the sore. (It is very, very bitter so instantly triggers saliva.) Hold the Alum there with a finger for a moment to prevent it from washing/spreading into mouth. Bingo, the canker sore was gone almost immediately.

    As an adult I found Alum in the baking center of the grocery store, used it as my mother taught me, and my or my children’s canker sore healed almost immediately. Alum is pure basic which neutralizes acid. Cheap remedy.

  7. Shirley
    Huntsville Tx

    I put a small amount of hydrogen peroxide in a small cup (I use the mouthwash lid), add about 4-6 drops of Tea Tree Oil, and a little water. I swish this thoroughly and spit it out. Then I wait about 30 seconds and rinse. (Don’t swallow the solution.) This works completely after a couple of days of doing this routine twice day. Works every time.

  8. mary
    montreal, canada

    Defintely baking soda works. I am 75 and when I get a canker sore – I put some baking soda directly on and leave it there. It usually is gone within 24 hrs. MAS

  9. Neila

    When I was a child my mother told me to put Alum on them and they went away in a couple of days and the pain disappeared quickly. When I get one now that is what I use and it stops them. Everyone’s body is different and what works for one doesn’t necessarily work for all. They are so painful! I got mine when a child from some diet pills that I was taking. The sores were ALL around both my upper and lower teeth. Hard to talk, eat, or anything else.

  10. Carol Holland

    I use povidone iodine on a q-tip and dab the spot it heals fast. I also use a vitamin c tablet that is chewable and place it on the canker sore and do it over and over again until the sore disappears. Oral sore throat sprays work too use the same technique as iodine dab with a q-tip until the sore dries up. All the above remedies stop the pain fast.

  11. Dallas
    Seabrook, TX

    I’ve suffered from occasional canker sores for about 60 years. I’ve tried many products but only had good success with one and surprised that it is not mentioned here – maybe because it requires a prescription. Anyway, years ago a doctor prescribed Triamcinolone Acetonide Dental Paste .1%. I keep a prescription on hand at all times now. If you dab a little on at bedtime as soon as you sense it coming on the canker sore goes away in a day or 2. The more you procrastinate the longer it will take. As I’ve changed doctors over the years I’ve had to educate them as few have seemed to know what it is or is for. As for other products: my dad make me try the baking soda dissolved in water one time when I complained to him. It didn’t help me but I sure never told him I had a canker sore again. I got no relief at all from l-lysine. I tried Canker Melts one time and they seemed to work but only if I could keep them on the sore for some time and that was very difficult.

  12. Nancy
    Dallas, Texas

    I, too, have suffered all my life with canker sores. Somewhere, maybe here, I read about changing to a toothpaste without SLS (sodium laurel sulfate). The difference is amazing. I have now been free from canker sores for about 10 years and share “the cure” with anyone who mentions them.
    I was wondering, Since I am allergic to sulfa, couldn’t that be the culprit in the
    S-L-Sulfate toothpastes that causes a reaction in my mouth, forming those terrible sores?

  13. Kassy

    The fact that buttermilk helps some people makes me wonder if canker sores are a kind of yeast. Fermented dairy often helps with yeast infections. Other people say that nuts and chocolate trigger it and that L-Lysine helps get rid of it—–that makes me wonder if canker sores are a form of herpes.

  14. Ellie

    Sugar from candy and cookies, etc. definitely bring them on for me.

  15. PattyPR

    For immediate relief, I put a teabag (black tea- the ordinary l tea in the grocery store) on the spot, but mine are usually just inside one lip. A used tea bag works best. Sometimes, if it is in a place hard to out a full tea bag, I opoen it and use a white paper towel to make a smaller one. I take Lysine at the first hint of pain and it is gone in two days. I take the Lysine for a few days to a few weeks to keep it from coming back.

    Like some others here, I think there are multiple causes for canker sores, whteher food, acids. minir injuries, more. I was not aware of the SLS issue in toothpaste. What I do know is that, for me, eating anything acidic or carbonated drinks make them worse.

  16. Cara

    The reader who uses a stypic pencil is right on. It is alum. As a child, I iften had canker sores. My had a container of alum in the medicine cabinet. I would daub a bit of alum on the sores, and leave it for a little bit then spit. The sores always disappeared overnight. Alum is bitter. Be forewarned.

  17. R D Ward
    Boone, NC

    I had canker sores for many years. My remedies are making sure I brush my teeth every day (2 times), flossing every day and taking a probiotic every day. If I do these things, no canker sores.

  18. Art
    Albuquerque, NM United States

    I used to get those quite frequently for many,many years until I started taking Lysine. The problem was quickly cured and they’ve never returned. It’s been years now!

  19. Jeff

    I have tried many different treatments for my canker sores and I found eating a Kiwi daily helps most of the time. Now I rarely get these sores but another product that works for me is Durham’s Caner-Rid made from Bee products. However, it is painful when first applied but the upside is the canker sore goes away quickly with just a couple of treatments. You can get this on Amazon.

  20. Anne

    I get canker sores every so often, but right now I have a couple of them and the biggest, seemingly unending cold sore. I keep reading about how to stop them from growing and spreading. Well, too late for that! Please do something on managing the misery and discomfort when they seem out of control!

  21. Carol

    Whenever I get a canker sore, I put just a fingertip of salt on it. Leave for a minute and then rinse away. The sore is gone within hours.

  22. Page

    When I get canker sores I use Listerine twice a day (am= pm) and most always they are gone in 24 hours.

  23. Karen

    I would suggest having your husband tested for celiac disease. Before my diagnosis, i was plagued with constant canker sores–sometimes 7 or 8 at a time in my mouth at once. It was so painful for me. Since my diagnosis 11 years ago, I have only had maybe 3 canker sores and they were due to being cross-contaminated with gluten.

  24. Fredericka

    I used to get canker sores on my tongue from time-to-time. My father-in-law gave me some alum to apply to the sores. I’ve keep a container of alum in the bathroom every since. At the first sign of a problem I apply just what will stick to the end of my little finger. The sore is gone after a few applications.

  25. Ralph

    My wife has found that eating yogurt regularly has kept her free from canker sores for the last several years .

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