What Is the Difference Between an Injection of B12 and Taking It Under Your Tongue?

Sublingual vitamin B-12 can be as effective as injections.

Vitamin B-12 intake can have a significant impact on the everyday function of your body, including nervous system function, DNA replication and mood regulation. Vitamin B-12 deficiency can occur in people who do not eat a significant amount of animal-based foods, such as vegans. Your ability to absorb vitamin B-12 also decreases as you age; approximately 10 to 15 percent of people over the age of 60 have a vitamin B-12 deficiency, according to the Linus Pauling Institute. In most cases, the administration route of a vitamin B-12 supplement has little impact on its effect.

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Absorption Pathways

The primary difference between injections of vitamin B-12 and supplements you take sublingually -- the medical term for under the tongue -- is how the vitamin enters your system. The vitamin B-12 you ingest in foods requires stomach acids and certain enzymes to free it from proteins so the stomach can absorb it into the bloodstream. Supplements like pills and lozenges you place under your tongue are already freed and simply diffuse into your bloodstream. Injections are an even more direct method, delivering the vitamin B-12 straight to your blood.



Reviews of vitamin B-12 research seem to indicate you will benefit from a vitamin B-12 supplement whether you take it orally, under your tongue or with an injection. A 2003 review in the "British Journal of Clinical Pharmacology" found almost no difference in vitamin B-12 uptake when sublingual and oral supplements were compared. Similarly, a 2010 review in "Expert Opinion on Pharmacotherapy" concluded that sublingual vitamin B-12 supplements are at least adequate in treating deficiencies even if the body cannot absorb them as effectively as injections.


Pernicious Anemia

Speak to your doctor if you have a vitamin B-12 deficiency to determine which method of administration is most fitting for you. In cases of deficiency from your diet or aging, sublingual and injected vitamin B-12 would be equally effective. However, diseases like pernicious anemia drastically reduce your body's ability to orally absorb vitamin B-12. You can treat this condition with an oral supplement, but you would need to take a much higher dose to meet your daily needs, and an injection may be preferable.


In many cases, people prefer a sublingual vitamin B-12 supplement to an injection. Injections require you to draw up the medication and endure the mild pain associated with this delivery method. Taking vitamin B-12 sublingually is as simple as placing a quick-dissolving tablet under the tongue. Sublingual tablets may also be less expensive than the injection form.


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Vitamin B-12 supplements come in a variety of forms, including patches, oral tablets and sublingual lozenges. Vitamin B-12 lozenges placed directly under the tongue dissolve in the saliva, and the body absorbs the vitamin through the tissues in the mouth. No evidence shows that sublingual vitamin B-12 lozenges promote better absorption than other oral tablets, notes the National Institutes of Health Office of Dietary Supplements. However, studies have found this form to be just as effective as other oral supplements. Consult your doctor about vitamin B-12 supplements before beginning treatment.

Treating High Homocysteine Levels

Vitamin B-12 deficiency can lead to elevated homocysteine levels in the blood, a risk factor for cardiovascular disease, according to the National Institutes of Health Office of Dietary Supplements. In a 2006 study published in the "Journal of Alternative and Complementary Medicine," researchers from the University of Bridgeport College of Naturopathic Medicine found that supplementation treatment with both sublingual and oral vitamin B-complex significantly reduced homocysteine levels over a 6-week period.


Treating B-12 Deficiency

In a 2003 study published in the "British Journal of Clinical Pharmacology," researchers from the Sackler Faculty of Medicine at Tel Aviv University found that 500 microgram doses of sublingual vitamin B-12 were just as effective as 500 microgram doses of oral B-12 tablets at correcting existing vitamin B-12 deficiency.

Need for Supplements

A variety of health conditions can hinder vitamin B-12 absorption, increasing the risk for vitamin B-12 deficiency. B-12 deficiency can cause irreversible nervous system and neurological damage if left untreated. Individuals at high risk for vitamin B-12 deficiency include those with atrophic gastritis, pernicious anemia, Crohn's disease and celiac disease and those who have had gastrointestinal surgery. These individuals may benefit from sublingual vitamin B-12 supplements or other forms of supplements. According to data from the Framingham Offspring Study, people who eat fortified cereals more than four times per week or take vitamin B-12 supplements are less likely to have B-12 deficiency, notes the National Institutes of Health Office of Dietary Supplements.


Vitamin B-12 supplements contain varying doses. Consult your doctor to determine the appropriate dose for your needs. Doctors may suggest a 300 to 10,000 mcg dose of oral or sublingual vitamin B-12 for treatment of vitamin B-12 deficiency or pernicious anemia, according to MedlinePlus Medical Encyclopedia, and a 500 microgram dose of vitamin B-12 in combination with folic acid and pyridoxine for the treatment of increased homocysteine levels.