Does Vitamin B12 Help Canker Sores?What Trials Found

Canker sores, the small painful ulcers inside the mouth, can return again and again with no obvious reason. Vitamin B12 is one of the few simple treatments with a positive trial behind it.

The B12 trial

In an Israeli primary care trial, 58 people with recurrent canker sores took either 1,000 mcg of vitamin B12 under the tongue or a placebo for 6 months.¹

• By months 5 and 6, the B12 group had shorter outbreaks, fewer ulcers and less pain.¹
• In the last month, 74% of the B12 group were sore-free, against 32% on placebo.¹
• It worked regardless of people’s starting B12 levels.¹

It was a small trial, and the benefit took months to show.¹

The multivitamin trial

In Connecticut, 160 adults with at least three canker sore episodes in the past year took a standard daily multivitamin or a placebo for up to a year.²

	Multivitamin	Placebo
New episodes	4.192	4.602
Days per episode	8.662	8.992

There was no meaningful difference.² A multivitamin gives ordinary daily amounts, far less B12 than the 1,000 mcg used in the first trial.

The deficiency link

A review found people with low B12 were about 2.9 times as likely to get canker sores, and those with low iron stores about 2.5 times.³ That’s a good reason to have levels checked if sores keep returning.

What to do

1. Ask about blood tests for B12, iron and folate if you get sores often.
2. Consider a trial of B12 with your clinician’s agreement, giving it several months.¹
3. Look at other triggers, such as toothpaste. See SLS-free toothpaste and canker sores and why you keep getting canker sores.

See a dentist or doctor for a mouth ulcer that lasts more than 3 weeks, looks different from usual, or comes with ulcers elsewhere on the body or painful, swollen joints.⁴ See mouth sores that won’t heal.

Try: “I get canker sores almost every month. Could we check my B12 and iron, and would a trial of B12 make sense for me?”

Is It My Breath? covers mouth sores that need checking in Chapter 8, “Stones, Throats and Tongues,” in a section called “Patches That Need a Look.” Its Breath Log takes one line a day for time, food, dryness, taste and what you tried, so you can see whether sores ease on a new routine. See the book.