Sublingual B12: Does It Absorb Better Than a Pill?

Sublingual B12 is vitamin B12 you hold under the tongue, as a tablet, lozenge, drop or spray, instead of swallowing it. In the studies that compared the two, it raised B12 levels about as well as a swallowed pill of the same dose, not better. In 30 adults with low B12, 500 mcg a day taken under the tongue or swallowed raised blood levels by almost exactly the same amount after 4 weeks (Sharabi et al., 2003), and the NIH says evidence suggests no difference in efficacy between oral and sublingual forms (NIH ODS). This guide covers what sublingual means, how it compares with pills, injections and nasal sprays, and how to choose.

It is educational, not medical advice.

Key Takeaways

• Same result as a pill: 500 mcg a day under the tongue or swallowed raised serum B12 from about 94 to 288 pmol/L and from 108 to 286 pmol/L, with no significant difference between the groups (Sharabi et al., 2003).
• Same in a second trial: in 41 adults aged 50 to 80, a B complex with 1,000 mcg of methylcobalamin lowered homocysteine equally whether it was taken under the tongue or swallowed (Yazaki et al., 2006).
• High doses do the work: the body absorbs about 50% of doses under 1 to 2 mcg, but only about 2% of 500 mcg and 1.3% of 1,000 mcg taken by mouth (NIH ODS), which is why both pills and sublinguals use large doses.
• Compared with injections: in a review of 4,281 patient records, sublingual tablets raised B12 levels at least as much as injections, though the study was not randomized (Bensky et al., 2019).
• Nasal is a separate route: a nasal spray is absorbed through the lining of the nose, not under the tongue; a prescription nasal B12 gel raises blood levels, according to the NIH (NIH ODS).

What Is Sublingual B12?

"Sublingual" means under the tongue. Sublingual B12 comes as small tablets or lozenges that dissolve in the mouth, and as liquid drops and mouth sprays. The NIH lists sublingual tablets and lozenges as one of the common ways B12 is sold, next to ordinary pills, injections and a prescription nasal gel (NIH ODS).

The idea is that some B12 passes through the thin lining under the tongue straight into small blood vessels. Any part of the dose that is not taken up in the mouth is swallowed with saliva and then absorbed the same way as a pill. Most products use methylcobalamin or cyanocobalamin; our guide to methylcobalamin vs cyanocobalamin compares the two forms. Some products use hydroxocobalamin instead; our guide to methylcobalamin vs hydroxocobalamin covers how those two forms differ.

Is Sublingual B12 Better Than a Pill?

The trials that tested it head to head found no meaningful difference. In the first, 30 adults with low serum B12 were randomly assigned to 500 mcg of cobalamin a day under the tongue, the same tablet swallowed, or a B complex. After 4 weeks, serum B12 rose from 94 to 288 pmol/L in the sublingual group and from 108 to 286 pmol/L in the swallowed group, and the authors found no significant difference between the groups (Sharabi et al., 2003).

In the second, 41 adults aged 50 to 80 with raised homocysteine took a B complex containing 1,000 mcg of methylcobalamin, 400 mcg of folic acid and 5 mg of vitamin B6 for 6 weeks, either under the tongue or swallowed. Homocysteine fell in both groups, with no significant difference between them (Yazaki et al., 2006). The NIH cites both trials when it says evidence suggests no difference in efficacy between oral and sublingual forms (NIH ODS).

So the honest answer is that sublingual B12 works, but mainly because of the dose, not because the tongue is a shortcut. If you find small dissolving tablets easier than swallowing pills, that is a fine reason to choose them.

How B12 Absorption Works

B12 taken by mouth binds to intrinsic factor, a protein made by the stomach, before it is absorbed. That system fills up at about 1 to 2 mcg at a time (NIH ODS). Above that, only a small share of the dose gets in:

Oral dose	About how much is absorbed
Under 1 to 2 mcg	About 50%
500 mcg	About 2%
1,000 mcg	About 1.3%

Source: (NIH ODS). Two percent of 500 mcg is still about 10 mcg, several times the 2.4 mcg adults need each day (NIH ODS). That is why large oral doses work even in people who absorb B12 poorly: in a trial of 38 people with low B12, 2 mg of cyanocobalamin by mouth every day for 4 months worked as well as monthly injections and raised serum B12 further (Kuzminski et al., 1998). Our guide to whether you can take too much B12 covers what high doses mean for safety.

For the timeline from first dose to a full effect, see how long does B12 take to work?

Sublingual B12 vs Injections

Injections are the traditional way to give B12 when someone cannot absorb it well. A 2019 study looked back at pharmacy records for 4,281 adults in Israel who were prescribed B12: 3,451 used sublingual tablets and 830 had injections. Serum B12 rose by an average of 252 ng/L with sublingual tablets and 218 ng/L with injections (Bensky et al., 2019). Because it was a records review rather than a randomized trial, the groups may have differed in ways the study could not control, so it shows that sublingual tablets can raise levels well, not that they are better for everyone. Decisions about injections belong with your doctor.

Sublingual vs Nasal B12

Nasal B12 is a different route. A nasal spray is absorbed through the lining of the nose instead of being swallowed like a capsule, so some of each dose skips digestion; some of the spray also drains to the throat and is swallowed. The NIH notes that a prescription B12 nasal gel spray appears to be effective in raising B12 blood levels in adults and children (NIH ODS). In a small study of 10 adults over 65, a single 1,000 mcg intranasal dose had an estimated bioavailability of 2% (Tillemans et al., 2014), which the NIH describes as similar to an oral dose (NIH ODS).

Our Methyl B-12 Nasal Spray is a nasal spray, not a sublingual product: you spray it into the nose, not under the tongue. Our guide to B12 nasal spray explains how to use it and how it compares with injections.

Form	How you take it	What studies found
Swallowed pill	By mouth with water	2 mg daily matched monthly injections in a 4 month trial
Sublingual tablet or lozenge	Dissolve under the tongue	Raised levels the same as a swallowed pill of the same dose
Nasal spray or gel	Sprayed into the nose	Prescription nasal gel raises blood levels; small study estimated 2% bioavailability
Injection	Given by a clinician	The traditional route when absorption is poor

How to Take Sublingual B12

1. Follow the label. Most sublingual tablets and lozenges say to let them dissolve fully under the tongue before swallowing.
2. Pick a time you will remember. Many people take B12 in the morning; our guide to the best time to take B12 explains why.
3. Do not stack products by accident. If you also take a multivitamin or a B complex, add up the B12. Our guide to B complex vs B12 helps you choose one.
4. Eat B12 foods too. Our list of vitamin B12 foods covers the best sources.

When to Talk to a Doctor

Stomach acid reducing medicines, such as proton pump inhibitors and H2 blockers, can interfere with absorbing B12 from food, and metformin might reduce B12 absorption and blood levels (NIH ODS). If you take any of these, follow a vegan diet, are an older adult, or have numbness or tingling in your hands or feet, ask your doctor about checking your B12 rather than guessing at a form or dose (NIH ODS).

Where Our Products Fit

Our Methyl B-12 Nasal Spray provides 408 mcg of vitamin B12 as methylcobalamin per two-spray serving, used as two sprays once a day. It is designed for consistent daily use for people who would rather not swallow pills or dissolve tablets. The Energy Stack pairs it with NAD+ Nasal Spray and Forage in one daily energy routine. Learn more on our methyl B12 ingredient page and in our non-stimulant energy and focus hub. Talk to your doctor before starting a new product if you are pregnant, breastfeeding or take medication.

Frequently Asked Questions

Is sublingual B12 better absorbed than oral B12?

Not in the trials that compared them. 500 mcg a day raised serum B12 by about the same amount under the tongue or swallowed (Sharabi et al., 2003).

Is sublingual B12 absorbed in the mouth?

Partly at most. Some may pass through the lining under the tongue, but whatever is not taken up there is swallowed and absorbed like a pill. Results in trials matched swallowed tablets (NIH ODS).

Is sublingual B12 as good as injections?

In a records review of 4,281 people, sublingual tablets raised B12 levels at least as much as injections, but it was not a randomized trial (Bensky et al., 2019). Ask your doctor which route suits you.

How much sublingual B12 should I take?

Adults need 2.4 mcg a day (NIH ODS). Supplements usually contain far more because only a small share of a large dose is absorbed. Follow the label and ask your doctor if you have been told your B12 is low.

Can you swallow a sublingual B12 tablet?

Yes. A swallowed tablet of the same dose worked as well in the trial that compared them (Sharabi et al., 2003), though the label will tell you how the product is meant to be taken.

Is a B12 nasal spray the same as sublingual?

No. A nasal spray goes into the nose and is absorbed through the nasal lining, with some swallowed; sublingual products dissolve under the tongue. Our Methyl B-12 Nasal Spray is a nasal spray.

When is the best time to take sublingual B12?

Morning is the simple default, and food is optional because supplement B12 is already in free form (NIH ODS).

Sources

1. Sharabi A, Cohen E, Sulkes J, Garty M. Replacement therapy for vitamin B12 deficiency: comparison between the sublingual and oral route. Br J Clin Pharmacol. 2003. PubMed 14616423
2. Yazaki Y, Chow G, Mattie M. A single-center, double-blinded, randomized controlled study to evaluate the relative efficacy of sublingual and oral vitamin B-complex administration in reducing total serum homocysteine levels. J Altern Complement Med. 2006. PubMed 17109579
3. Bensky MJ, Ayalon-Dangur I, Ayalon-Dangur R, et al. Comparison of sublingual vs. intramuscular administration of vitamin B12 for the treatment of patients with vitamin B12 deficiency. Drug Deliv Transl Res. 2019. PubMed 30632091
4. Kuzminski AM, Del Giacco EJ, Allen RH, Stabler SP, Lindenbaum J. Effective treatment of cobalamin deficiency with oral cobalamin. Blood. 1998. PubMed 9694707
5. Tillemans MP, Donders EM, Verweij SL, Van der Hoeven RT, Kalisvaart KJ. Effect of administration route on the pharmacokinetics of cobalamin in elderly patients: a randomized controlled trial. Curr Ther Res Clin Exp. 2014. PubMed 25031664
6. NIH Office of Dietary Supplements. Vitamin B12: Fact Sheet for Health Professionals. NIH ODS
7. NIH Office of Dietary Supplements. Vitamin B12: Fact Sheet for Consumers. NIH ODS

Our products are not intended to diagnose, treat, cure or prevent any disease. This article is for education only and is not medical advice.