My must-haves for canker sores

A reader wrote in this week: “Is magnesium good for canker sores?”

Yes. But if magnesium is the only thing you change, you’ll probably be disappointed, because for most people the real trigger is sitting on the bathroom counter: their toothpaste.

Most toothpaste foams because of a detergent called sodium lauryl sulfate, or SLS, the same class of molecule as dish soap. (The cleaner I used on my garage floor for years was 50% SLS.)

That foam isn’t cleaning anything. It’s stripping away the thin, slippery mucin layer that protects the tender tissue inside your cheeks and lips, and once that shield is gone, the raw tissue underneath is primed to ulcerate.

Here’s the rule I’ve repeated for forty years: if your mouth burns, tingles, or feels raw after you brush, that isn’t clean; that’s damage to your oral microbiome.

Nobody warns you that a “healthy” brushing habit could be feeding your canker sores. But it doesn’t have to be that way.

My must-haves for anyone who gets canker sores

✔️ Magnesium, but not the drugstore kind. Canker sores can be a sign you’re running low, and most of us are. Just skip the cheap magnesium oxide on the shelf; you absorb almost none of it. Look for a high-quality, third-party-tested blend like this one. I love this stuff.→ Link

✔️ SLS-free nano-hydroxyapatite toothpaste. This is the switch that matters most. No SLS, no foaming detergents to strip your mucin layer, and nano-hydroxyapatite to rebuild enamel while you’re at it. (Full disclosure: I co-founded Fygg, because for years no SLS-free toothpaste included nHAP and I was tired of the trade-off.) Whatever brand you pick, read the label because SLS hides under a dozen other names.→ Link

✔️ Zinc-rich foods. Zinc is the other mineral tied to how fast a sore heals. Load your plate: oysters (by far the richest source), beef, lamb, crab, pumpkin and hemp seeds, cashews, chickpeas, and lentils.

✔️ A super-saturated salt rinse (for an active canker). This one’s free, and it genuinely works, but only if you make it strong enough. Stir a high quality salt into warm water and keep adding it until it stops dissolving; most people toss in a spoonful, call it done, and wonder why it didn’t do anything. Rinse for a full five minutes, four times a day. The salt draws fluid out of the swollen tissue, brings blood flow to the area, and helps the ulcer close over faster; the exact opposite of what a stripping mouthwash does.→ Link

✔️ Mouth tape. Sleep with your mouth open and you dry out that same mucin layer for eight hours straight, waking up with tissue that’s parched and easy to ulcerate. And if you already have a sore, that overnight dryness is brutal and it stalls the healing, because saliva is what soothes and repairs that tissue in the first place. That’s its whole job. Tape keeps you breathing through your nose all night so your saliva can do that work and you’ll sleep better for it.
→ Link

One caveat: if your canker sore shows up in the exact same spot every time, that’s not minerals or toothpaste — it’s mechanical. A sharp tooth, or a rough edge on a night guard, catching the same place over and over. Your dentist can smooth it in five minutes.

– Dr. B

P.S. Skip the hydrogen peroxide and Listerine—and not just when you have a sore. I steer everyone away from them, because both strip the protective layer off your entire mouth. But with an active canker sore it’s even worse: there’s no infection there to kill in the first place, so all that “disinfecting” does is scald already-raw tissue and drag the healing out for days longer. A much better rinse is this oil pulling blend which nourishes the mouth rather than strips. I broke down all five root causes of recurring canker sores here.