Written by the Nuvirox Research Team
Key points
- Recurrent canker sores (aphthous stomatitis) affect up to a quarter of adults, and a nutrient gap — especially vitamin B12 — is one of the few modifiable factors with trial evidence behind it.
- A randomized trial found sublingual B12 cut ulcer frequency, duration, and pain, but a separate trial of a generic multivitamin found no benefit — the nutrient has to be one you're actually short on.
- Stress and minor mouth trauma remain the most common everyday triggers, and most sores resolve within 7–14 days without treatment.
Short answer: sometimes yes, and it's worth a look at B12 — but for most people, canker sores are just an unlucky mix of minor trauma, stress, and genetics, not a sign anything is seriously wrong. If you've noticed you're getting more of these small, painful mouth ulcers than you used to, you're not imagining a pattern. Recurrent aphthous stomatitis, the clinical name for canker sores, is common enough that researchers estimate it affects roughly a quarter of the general population at some point, and a subset of people get them in repeated waves rather than as one-off events.
What actually causes a canker sore?
Nobody has pinned down one single cause. The honest picture from the literature is a cluster of contributing factors: minor trauma from biting your cheek or a rough edge on a filling, acidic or abrasive foods, stress, hormonal shifts, and — in a meaningful subset of recurrent cases — a nutritional gap in vitamin B12, iron, or folate. Genetics also plays a role; if a parent had frequent canker sores, you're more likely to as well.
What's changed for you specifically is harder to say without knowing your history. A new toothpaste with sodium lauryl sulfate, a stretch of poor sleep and higher stress, a new medication, or simply eating more acidic or crunchy foods can all tip the balance. If the pattern is new and persistent, it's reasonable to look at what else has changed in the same window.
Why does vitamin B12 keep coming up?
B12 plays a role in the rapid cell turnover of oral mucosa, and several older case-control studies found lower B12 levels in people with recurrent aphthous stomatitis compared to controls. That correlation is why researchers eventually tested B12 supplementation directly, in patients who weren't necessarily diagnosed as B12 deficient.
What human studies actually show
Volkov et al. (2009), a randomized, double-blind, placebo-controlled trial gave 58 adults with recurrent aphthous stomatitis either 1,000 mcg of sublingual vitamin B12 or a matching placebo nightly for six months. The B12 group saw significantly reduced outbreak duration, ulcer count, and pain scores compared to placebo — notably, this benefit showed up even though most participants weren't clinically B12-deficient at baseline, suggesting the effect may work through a mechanism beyond simply correcting a deficiency.
Lalla et al. (2012), a randomized, double-masked, placebo-controlled trial in 160 adults tells the honest counterweight: a once-daily multivitamin containing 100% of the RDI of standard vitamins showed no significant difference from placebo in the number (4.19 vs. 4.60 episodes) or duration of new ulcers over a year. The takeaway isn't that nutrients are irrelevant — it's that a broad-spectrum multivitamin at standard doses doesn't reliably help, while targeted B12 in the specific trial above did.
Huling et al. (2012) found that stressful life events were associated with both the onset and the duration of aphthous outbreaks in a cohort of RAS patients, reinforcing that stress isn't just an anecdotal trigger — it shows up in prospective data too.
What canker sores won't tell you
A single canker sore is not a red flag. But if sores are unusually large (over a centimeter), take more than three weeks to heal, come with fever or swollen lymph nodes, or cluster with other symptoms like fatigue or joint pain, it's worth a conversation with a doctor or dentist — those patterns can occasionally point to conditions like Behçet's disease, inflammatory bowel disease, or a more significant nutrient deficiency than typical RAS. Canker sores are also not the same as cold sores, which are caused by herpes simplex virus and usually appear on the outer lip.
What actually helps in the meantime
For an active sore, over-the-counter topical benzocaine or a saltwater rinse can ease pain while it heals on its own, typically within 7–14 days. If outbreaks are frequent, asking your doctor to check B12, iron, and folate levels is a reasonable, low-cost first step before trying supplements blindly — the trial evidence for B12 is strongest in people who actually have room to improve.
Frequently asked questions
Are canker sores contagious? No. Unlike cold sores, canker sores aren't caused by a transmissible virus, so you can't catch or spread them through kissing or sharing utensils.
Does stress really cause canker sores, or does it just feel that way? Prospective research has linked stressful life events to both new outbreaks and longer healing times, so the connection isn't purely anecdotal, even if stress alone doesn't explain every case.
Should I just start taking a B12 supplement? If outbreaks are frequent, ask your doctor to check your levels first. The trial showing benefit used a specific sublingual dose over six months in people who weren't necessarily deficient, so it's reasonable to discuss with a clinician rather than guess at dosing.
Can toothpaste really trigger them? Some research has linked sodium lauryl sulfate (SLS), a foaming agent in many toothpastes, to increased canker sore frequency in susceptible people, though the evidence isn't conclusive. Switching to an SLS-free toothpaste is a low-risk thing to try if outbreaks are frequent.
Do canker sores get more or less common with age? Interestingly, recurrent aphthous stomatitis tends to be more common in younger adults and adolescents, with frequency typically decreasing with age — so if you're noticing more sores later in life, it's more likely tied to a specific new trigger (diet, stress, a nutrient shift, a new dental appliance) than to aging itself.
Mouth-related discomfort tends to cluster: if you're also dealing with a jaw that tires out faster than it used to or catching yourself clenching your jaw during the day, it's worth looking at oral habits and stress together rather than treating each symptom as unrelated, since stress is a documented contributor to more than one of these.
A note before the product section: Canker sores are usually harmless and self-limited, but recurrent or unusually large ulcers can occasionally signal a nutrient deficiency or, rarely, an underlying condition worth ruling out with a doctor or dentist — especially if they're accompanied by fever, weight loss, or joint symptoms.
From Nuvirox
Why we formulated NAD+ Restore
Recurrent mouth ulcers are a reminder that mucosal tissue is constantly rebuilding itself, and that turnover depends on the cellular energy every dividing cell needs. NAD+ is a coenzyme central to how your cells generate that energy. NAD+ Restore is currently being reformulated, so we're not listing specific ingredient amounts here — check the current product label for exact formulation details. Every order is backed by our 60-day money-back guarantee, long enough to actually evaluate it the way the research above suggests you should.
Learn more about NAD+ Restore →The bottom line
If canker sores have become a recurring nuisance, the fair reading of the evidence is that a targeted B12 check is worth more than reaching for a generic multivitamin, and that stress management is a legitimate (if imperfect) lever. Most outbreaks remain benign and self-limited — but persistent, severe, or unusual patterns deserve a professional look rather than repeated home remedies.
References
- Volkov I, Rudoy I, Freud T, et al. Effectiveness of vitamin B12 in treating recurrent aphthous stomatitis: a randomized, double-blind, placebo-controlled trial. J Am Board Fam Med. 2009;22(1):9-16. PMID: 19124628.
- Lalla RV, Choquette LE, Feinn RS, et al. Multivitamin therapy for recurrent aphthous stomatitis: a randomized, double-masked, placebo-controlled trial. J Am Dent Assoc. 2012;143(4):370-376. PMID: 22467697.
- Huling LB, Baccaglini L, Choquette L, Feinn RS, Lalla RV. Effect of stressful life events on the onset and duration of recurrent aphthous stomatitis. J Oral Pathol Med. 2012;41(2):149-152. PMID: 22077475.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for professional medical advice.