Natural Remedies and Home Remedies for Canker Sores — Do They Actually Work?

The Problem With Canker Sore Home Remedy Articles

Most articles on this topic are lists. They aggregate whatever people report trying, add a disclaimer, and call it a day. This article is different: every remedy gets a mechanism explanation and a verdict based on actual evidence.

Some remedies are supported. Most aren't. A couple are actively counterproductive. Knowing the difference matters if you're trying to get better faster, not just doing something that feels productive.

Salt Water Rinse

Verdict: Weak Evidence — Mild Benefit Likely

A salt water rinse is the most universally recommended canker sore remedy, and the evidence is weak but not zero.

Mechanism: Salty water draws fluid out of the swollen tissue around the ulcer, which can take down some of the swelling and inflammation. Salt is also mildly antibacterial, so it keeps the ulcer cleaner.

What the evidence shows: No published RCT has specifically tested salt water rinse for aphthous ulcers. The evidence base is expert opinion and physiological rationale. The reduction in bacterial load is plausible; the anti-inflammatory effect is modest at best.

Verdict: Won't heal faster. May reduce pain modestly. No harm. 1/2 teaspoon in 8oz warm water for 30 seconds — that's the physiologically reasonable protocol.

Antiseptic Mouthwash (Listerine)

Verdict: Weak Evidence — Thin and Possibly Slanted

Standard Listerine contains 21–26% alcohol, and alcohol stings on an open ulcer. Canker sores are immune-mediated, not bacterial infections, so antiseptic action doesn't address the root cause — though reducing secondary bacterial colonization of the open wound may play a minor role, which is the proposed mechanism behind chlorhexidine's modest benefit.

There is one trial: over 6 months, people with recurrent canker sores who rinsed twice daily with Listerine had shorter, less painful ulcers, while a plain alcohol-and-water control rinse did not produce that effect (Meiller et al., 1991 — Oral Surg Oral Med Oral Pathol 72:425). It has never been replicated, its results were reported mainly against baseline rather than head-to-head, and Listerine's manufacturer at the time is acknowledged in the paper.

Verdict: Not harmful beyond the sting, but one unreplicated study isn't enough to recommend it. Prescription chlorhexidine has more consistent evidence.

Hydrogen Peroxide

Verdict: Weak Evidence — Possible Harm

Hydrogen peroxide is frequently recommended for its "antiseptic" properties. The evidence doesn't support it as a canker sore treatment, and there's a legitimate concern about harm.

Mechanism concern: Hydrogen peroxide is toxic to the cells lining your mouth. Even at the standard 3% drugstore strength, it damages the very repair cells that are trying to close the ulcer, which works against healing. Prolonged use also causes a harmless but unpleasant condition called "hairy tongue" and throws off the natural balance of bacteria in your mouth.

What the evidence shows: No RCT evidence for aphthous ulcers. The American Dental Association does not recommend hydrogen peroxide for aphthous ulcer treatment.

Verdict: Skip it. The theoretical antiseptic benefit doesn't outweigh the mucosal irritation risk for open ulcers.

A note on honey and H2O2: You may have read that Manuka honey's mechanism includes hydrogen peroxide. This is accurate, but the concentrations are incomparable: honey produces H2O2 at roughly 0.001% through glucose oxidase activity when diluted by wound fluid — about 3,000 times weaker than the 3% bottle from the pharmacy. At that concentration, H2O2 has antibacterial properties without cytotoxic effects. Applying drugstore H2O2 directly to an open sore is a completely different scenario.

Manuka Honey

Verdict: Supported — Moderate Evidence

Honey in general, and Manuka honey specifically, has more legitimate evidence than most remedies on this list — including a head-to-head trial against a prescription steroid.

Mechanism: Manuka honey's healing power comes mainly from a compound called methylglyoxal (MGO), which is antibacterial, plus a small amount of naturally produced hydrogen peroxide. Honey also draws in and holds moisture, keeping the ulcer surface moist — which the lining needs to heal. And it's mildly acidic (pH ~3.5–4.5), enough to discourage bacteria but not so acidic that it damages healing tissue (unlike apple cider vinegar — see below).

What the evidence shows: Several small randomized trials support topical honey for canker sores. The largest: El-Haddad et al. compared honey with a steroid paste and with Orabase, a plain protective paste, in 94 people with 180 ulcers. Honey did better than both on ulcer size, days of pain, and redness (El-Haddad et al., 2014 — PMID: 25019115). A 2025 trial found thyme honey did better than a steroid paste too (Ghalwash et al., 2025 — PMID: 39723829), and two other trials found honey about as good as a steroid. These trials used ordinary and thyme honeys. Manuka, the honey used in FDA-cleared medical wound dressings, has the strongest wound-healing track record, though it hasn't had a canker sore trial of its own.

Verdict: Supported by several small trials. Dab honey on the dried ulcer a few times a day and don't eat immediately after. Raw honey is a reasonable cheap option; certified Manuka or a honey gel costs more and isn't proven to work better. For a full breakdown of grading systems and which products to buy, see our Manuka Honey for Canker Sores guide.

Baking Soda Paste

Verdict: Debunked (No Evidence, Possibly Counterproductive)

Baking soda (sodium bicarbonate) paste is commonly recommended to "neutralize acid" and reduce pain.

Mechanism analysis: The "neutralize acid" rationale is based on a misunderstanding. Canker sores are not caused by acid. The ulcer pain comes from exposed nerve endings in damaged tissue — alkaline paste doesn't address this. Baking soda is also mildly abrasive and can irritate already-damaged mucosa.

What the evidence shows: No RCT evidence. No compelling mechanistic rationale.

Verdict: Skip it. The rationale doesn't hold up, and the abrasive texture may irritate the ulcer.

Aloe Vera

Verdict: Weak Evidence — Inconsistent Results

Aloe vera has anti-inflammatory properties in some wound-healing contexts, and there's one small placebo-controlled trial in canker sores.

Mechanism: Aloe vera gel contains compounds that can calm inflammation and support wound healing in some settings.

What the evidence shows: In a small double-blind trial of 40 people with minor canker sores, a 2% aloe vera gel applied three times a day led to shorter healing times, less pain, and less inflammation around the sore than a placebo gel (Babaee et al., 2012 — Dent Res J). It's one small trial, and an independent appraisal rated it low-level evidence, but it's a real result in canker sores.

Verdict: Weak but positive evidence. One small trial found faster healing and less pain with a 2% aloe gel. Pure aloe vera gel (not commercial products with alcohol or preservatives that will burn) is unlikely to harm.

Milk of Magnesia

Verdict: No Strong Evidence

Milk of magnesia (magnesium hydroxide suspension) is applied topically to "coat" the ulcer and neutralize oral acidity.

Mechanism analysis: Similar to baking soda, the acid-neutralizing rationale doesn't address the actual mechanism of aphthous ulcers. Magnesium hydroxide does have a mild anti-inflammatory effect at high concentrations, but topical application to an ulcer is short-lived.

What the evidence shows: No quality RCTs. Anecdotal reports of temporary comfort, likely from the physical coating effect on exposed nerve endings — the same benefit you'd get from anything viscous applied to the wound.

Verdict: Not worth seeking out. If it's already in your medicine cabinet and you find the coating sensation soothing, no harm done.

Ice

Verdict: Temporary Relief Only — No Healing Effect

Applying ice to a canker sore numbs the area through cold-induced analgesia. That's it.

Mechanism: Cold slows down the nerves carrying pain signals, so it numbs temporarily. No effect on inflammation. No effect on healing speed. The moment the area warms back up, the pain returns.

Verdict: Fine for short-term pain relief during a meal. Not a treatment. Ice temporarily narrows the blood vessels in the area, which may even slightly slow healing by reducing blood flow to the ulcer.

Apple Cider Vinegar (ACV)

Verdict: Debunked — Likely Harmful

Apple cider vinegar is among the most aggressively promoted home remedies online. It is also among the least scientifically supported and potentially the most harmful for canker sores.

Mechanism analysis: ACV is roughly 5% acetic acid, making it strongly acidic (pH 2–3). Putting something that acidic on an open sore in your mouth works against you: the acid burns tissue and kills the repair cells trying to rebuild the lining.

The argument that "acid kills bacteria" is not a reason to apply acid to an open wound. Benzocaine kills pain without destroying healing tissue.

What the evidence shows: No RCTs supporting ACV for aphthous ulcers. No plausible positive mechanism. Multiple case reports of ACV-induced oral burns.

Verdict: Do not apply ACV to canker sores. This is a case where the popular remedy is actively counterproductive.

SLS-Free Toothpaste

Verdict: Supported — Among the Strongest Interventions

SLS-free toothpaste doesn't treat an existing ulcer, but it's included here because it's often listed alongside home remedies and the evidence for it is better than most.

Switching from regular to SLS-free toothpaste cut canker sores by about two-thirds in a small 10-person study (Herlofson & Barkvoll, 1994 — PMID: 7825393); a larger trial found it mainly made sores less painful (Shim et al., 2012 — PMID: 22435470). SLS — the detergent that makes toothpaste foam — strips away the thin protective film over your mouth's lining, leaving it more exposed. Removing it prevents sores; it won't heal one you already have.

Verdict: Do this. It's the highest-evidence, lowest-effort intervention available.

Putting Toothpaste Directly on a Canker Sore

Verdict: Debunked (No Evidence, Likely Makes It Worse)

This one gets passed around on Reddit and in "life hack" lists: dab some toothpaste on the sore, leave it there, and it'll dry out and heal faster. It's borrowed from the old trick of putting toothpaste on a pimple, which dermatologists don't recommend either.

Why people think it works: Toothpaste tingles. Mint oils like menthol create a cooling feeling that briefly distracts from the pain, and the paste feels like it's "drying out" the sore. A strong sensation feels like treatment.

Why it likely backfires: Most toothpastes contain sodium lauryl sulfate (SLS), the foaming detergent described in the section above. SLS strips the protective film over the lining of your mouth, which is the reason switching to an SLS-free toothpaste is one of the better-supported prevention steps. Holding SLS directly against raw tissue for minutes is the most concentrated version of that exposure. Strong flavorings, especially cinnamon, are a well-known cause of irritation and allergic reactions inside the mouth, and the abrasives in toothpaste are designed to polish enamel, not to sit in an open wound. "Drying out" also isn't how a canker sore heals. Your mouth is always wet, and the sore closes as new lining grows in from the edges.

What the evidence shows: No study has tested toothpaste applied to a canker sore. The toothpaste research is all about which toothpaste you brush with, and it points the other way: brushing with SLS toothpaste is linked to more sores, not fewer (Herlofson & Barkvoll, 1994 — PMID: 7825393).

Verdict: Skip it. At best it does nothing. With a regular SLS toothpaste, you're pressing an irritant into an open wound. If you want something on the sore, a barrier patch protects it from food and teeth, and honey (above) has actual trials behind it. If brushing near the sore hurts, brush gently around it with an SLS-free toothpaste.

Chamomile Tea Rinse

Verdict: Weak to Moderate Evidence — Worth Trying

Chamomile is one of the more legitimate herbal remedies on this list. It contains three compounds with real anti-inflammatory activity: apigenin (a flavonoid that inhibits inflammatory enzymes), bisabolol (promotes wound healing in epithelial tissue), and chamazulene (an anti-inflammatory sesquiterpene formed during steam distillation). These aren't vague "natural healing" claims — the mechanisms are characterized.

What the evidence shows: In a small randomized trial of 36 people, a chamomile mouthwash led to fewer ulcers by day 4 and less pain and burning than a placebo rinse (Seyyedi et al., 2014 — J Clin Exp Dent). The trial didn't compare chamomile with a steroid, so it can't tell you how chamomile stacks up against standard treatment. It used a prepared chamomile tincture rather than home-brewed tea, so tea may be weaker.

How to use: Brew a strong chamomile tea (2–3 bags or 2 tablespoons loose flower in 1 cup boiling water), steep 10 minutes, let cool completely to room temperature. Swish gently for 30–60 seconds, 3–4 times daily. Don't use while hot — adding thermal trauma to an open sore is counterproductive.

Verdict: The evidence is for a standardized extract, not a home brew — so treat this as "promising but unproven at the home-use level." The mechanism is plausible, it beat a placebo in one small trial, and the risk is minimal (avoid it if you're allergic to ragweed or daisies). Worth trying alongside other interventions. Use whole-flower organic chamomile, not generic dust-filled bags, for the best home approximation.

Alum (Potassium Alum)

Verdict: Not Recommended at Home (One Small Trial, Real Burn Risk)

Alum (potassium aluminum sulfate) is the astringent sold in the spice aisle for pickling and in styptic pencils. It binds and tightens surface proteins, which can dull the pain of an open sore.

What the evidence shows: Unlike most home remedies, alum has a randomized trial behind it. In 50 patients, a mucoadhesive patch containing 7% alum healed canker sores in an average of 7.5 days versus 12.2 days with a plain patch, with less pain (Rafieian et al., 2016 — PMID: 27757206). But that was a dilute, controlled-dose patch made for the study. What people actually do at home is press concentrated powder or a wet crystal against the sore, and that has never been tested.

The risk: Concentrated alum is caustic. In one published case, a person who repeatedly dissolved alum against a palate ulcer developed tissue death and a hole through the roof of the mouth (Pinheiro et al., 2017 — PMID: 28833282).

Verdict: Don't apply alum yourself. The trial result is interesting, but it doesn't carry over to spice-aisle alum, and the downside is serious. See Alum for Canker Sores for the full breakdown.

Coconut Oil

Verdict: Weak Evidence — Not Harmful, Not Effective

Coconut oil is recommended for canker sores based on the lauric acid content (~49% of coconut oil), which has real antimicrobial properties, and because it's widely used in oil pulling. The antimicrobial logic doesn't apply here: canker sores are immune-mediated, not bacterial. Lauric acid killing oral bacteria doesn't interrupt the CD8+ T-cell attack producing the ulcer.

Applied directly to an active ulcer, coconut oil creates a temporary hydrophobic coating that briefly reduces saliva and food contact with exposed nerve endings — similar to any physical barrier, but washing away within minutes. Not harmful; not therapeutic.

Oil pulling (swishing coconut oil for 15–20 minutes) has modest evidence for general oral hygiene. No clinical trials for aphthous ulcers exist, and the mechanism doesn't translate.

Verdict: Won't make things worse. Won't help. If you use it for oral health generally, fine — don't expect it to change canker sore frequency or healing time. See Coconut Oil for Canker Sores for the full breakdown.

Summary Table

For actual treatment of an existing ulcer, see: How to Get Rid of a Canker Sore Fast →