What Vitamin Goes Under Your Tongue? A Guide to Sublingual B12

January 9, 2026 •

4 min read

According to one study, nearly 40% of Americans may not be getting enough vitamin B12, a critical nutrient for energy production and nerve health. This statistic highlights why understanding what vitamin goes under your tongue is important for those seeking efficient supplementation.

Quick Summary

Sublingual delivery is most commonly used for vitamin B12, which is absorbed under the tongue directly into the bloodstream. It is an effective alternative for individuals who have difficulty absorbing nutrients through the digestive tract.

Key Points

Vitamin B12 is the most common sublingual vitamin: It is widely available in sublingual form due to its complex absorption pathway via the digestive system.
Sublingual delivery offers direct absorption: The supplement is absorbed through the highly vascularized mucous membranes under the tongue, bypassing the gastrointestinal tract and liver.
It benefits those with absorption issues: Individuals with pernicious anemia, digestive disorders, or those who have had gastric surgery can benefit from the sublingual route.
Methylcobalamin is the natural form: This bioactive form of B12 can be used directly by the body, while the synthetic form, cyanocobalamin, requires conversion.
Other sublingual options exist: Some Vitamin D3 and Melatonin supplements are also available in sublingual delivery formats.

The Sublingual Absorption Pathway

Sublingual administration, which literally means "under the tongue," involves placing a supplement in liquid, spray, or dissolvable tablet form beneath the tongue. The area under the tongue and inside the cheeks is rich with tiny capillaries, or blood vessels, and is lined with a thin, permeable mucous membrane. This allows nutrients to be absorbed directly into the bloodstream, bypassing the digestive system and the first-pass metabolism in the liver. For some vitamins, this can lead to faster and more efficient absorption compared to traditional oral pills, which must first survive stomach acid and digestive enzymes.

The Prominence of Vitamin B12

While other nutrients can be taken sublingually, vitamin B12 is by far the most well-known and widely available sublingual vitamin. This is because its natural absorption pathway through the gut is complex and prone to issues for certain individuals.

Why B12 Benefits from Sublingual Delivery

Traditional B12 absorption requires two steps: stomach acid separates B12 from food proteins, and then a protein called intrinsic factor, produced in the stomach, binds to B12 for absorption in the small intestine. Many people experience impaired absorption due to:

Age: As people get older, their bodies produce less stomach acid and intrinsic factor, making B12 absorption more difficult.
Digestive Issues: Conditions like pernicious anemia, atrophic gastritis, Crohn's disease, or gastric surgeries (such as bariatric surgery) can reduce the body's ability to absorb B12 via the digestive tract.
Vegan/Vegetarian Diets: Since natural B12 is found almost exclusively in animal products, vegans and vegetarians are at higher risk for deficiency and often require supplementation.

For these individuals, the sublingual route offers a reliable way to get this essential nutrient into their system without relying on a compromised digestive process.

Forms of Sublingual B12: Methylcobalamin vs. Cyanocobalamin

Sublingual B12 supplements are available in two main forms, which have different characteristics and are processed slightly differently by the body.


Comparison of B12 Forms	Feature	Methylcobalamin	Cyanocobalamin
Source	Natural, bioactive form.	Synthetic, lab-made form.
Chemical Structure	Contains a methyl group.	Contains a cyanide molecule, though in harmless trace amounts.
Body Processing	Used directly by the body without conversion.	Must be converted into methylcobalamin and adenosylcobalamin.
Retention Rate	Possibly higher retention in the body.	Some studies suggest it is more readily excreted.
Cost	Often more expensive due to production.	Less expensive and more stable for manufacturing.

Some research suggests that methylcobalamin is more bioavailable and better retained, particularly for those with methylation issues. However, other studies show minimal difference in effectiveness, and both forms successfully correct B12 deficiency. For most people, the most important factor is consistent supplementation, regardless of the form.

What Other Sublingual Vitamins Are There?

While B12 dominates the sublingual market, other vitamins and supplements are also available in this form to leverage the direct absorption pathway.

Vitamin D3: Sublingual drops or sprays of Vitamin D3 are available and can be beneficial for individuals who have poor oral absorption of standard supplements. A case report showed that a patient with persistent deficiency responded well to sublingual Vitamin D3 after oral supplements failed.
Melatonin: As a sleep aid, melatonin is also sold in sublingual form to facilitate faster onset of its effects.
B-Complex: Many manufacturers offer sublingual B-Complex formulas that include a blend of B vitamins.

Factors Influencing Sublingual Absorption

For effective sublingual supplementation, it is important to follow usage instructions carefully. Factors that can affect absorption include:

Residence Time: The supplement must be held under the tongue until it fully dissolves. Swallowing the product can send it to the stomach, negating the benefits of the sublingual route.
Oral Hygiene: Good oral health and proper saliva flow are important for creating an optimal environment for absorption.
Purity: Sublingual products are often formulated with minimal additives, as they must be absorbed directly. It is important to choose high-quality products.

Conclusion: Making the Right Choice

Choosing the right vitamin and delivery method is a personal health decision that should involve a healthcare provider. While many vitamins are available sublingually, vitamin B12 is the most prominent and clinically significant, especially for those with compromised digestive function. The sublingual route, whether through dissolvable tablets or liquid drops, offers an efficient way to supplement this vital nutrient, bypassing the traditional gastrointestinal barriers to absorption. For individuals with a diagnosed B12 deficiency, digestive disorders, or specific dietary restrictions like veganism, sublingual B12 can be an effective and convenient option.

Consider discussing your specific needs and a testing plan with your doctor to ensure you are selecting the best supplementation strategy. For additional information, the National Institutes of Health provides comprehensive fact sheets on vitamins and minerals.

Frequently Asked Questions

A sublingual vitamin is a supplement, typically a liquid, spray, or dissolvable tablet, that is placed under the tongue. It absorbs directly into the bloodstream through the mouth's mucous membranes, bypassing the digestive system.

For individuals with compromised digestive absorption, sublingual B12 can be more effective than a standard oral pill. For those with normal digestion, studies have shown sublingual and oral B12 to be similarly effective at resolving deficiencies.

People with pernicious anemia, digestive disorders like Crohn's disease, vegans, vegetarians, and older adults who have reduced intrinsic factor production are strong candidates for sublingual B12.

The two main forms are methylcobalamin (natural and bioactive) and cyanocobalamin (synthetic, requiring conversion). Both are effective, but methylcobalamin is often preferred for direct use by the body.

Yes, while B12 is most common, sublingual forms of Vitamin D3 and Melatonin are also available. Some B-Complex supplements are also formulated for sublingual delivery.

You should place the supplement under your tongue and hold it there until it has completely dissolved and been absorbed. It is important not to chew or swallow it immediately, as this will send it through the digestive tract.

If your fatigue is caused by a vitamin B12 deficiency, then correcting the deficiency with sublingual B12 can help improve your energy levels. Vitamin B12 is essential for energy metabolism.