Liquid vitamin B12, also known as methylcobalamin, is a form of vitamin b12 that is taken sublingually, meaning beneath the tongue, instead of by way of patch, pill, nasal spray, or injection. Vitamin B12 is one of the eight essential water-soluble vitamins. In liquid form, it is most commonly used to treat symptoms of vitamin deficiency. It is also used for many other reasons to promote health in those both young and old.

Liquid vitamin B12 is packaged in a small plastic bottle with an eyedropper lid. To use, one fills the eyedropper, places a few drops under the tongue, holds for 30 seconds, then swallows. Sometimes liquid vitamin B12 is labeled B12 complex, which means it contains other B vitamins, such as riboflavin, thiamin, niacin, folate, vitamin B6, Pathothenic acid, and biotin. It may also contain vitamin C. Since vitamin B12 has a flavor that many consider unpleasant, a fruit flavoring is often added.

In the liquid form, vitamin B12 is concentrated and is thought to be similar in efficacy to that given in injections. Some individuals prefer liquid vitamin B12 to injections for reasons of convenience. In the liquid form, it does not require a visit to the doctor; it is widely available over-the-counter in pharmacies, health food stores, and retail chains. It is also less expensive than vitamin B12 injections.

Many people also prefer liquid vitamin B12 to patches and pills. For individuals who take vitamin B12 to control appetite, the liquid is often preferred because it gets into the blood stream almost instantly instead of being slowly absorbed in the stomach. It is also commonly used to enhance memory, boost energy, and increase concentration. In these situations, instant delivery is also preferred.

Research has revealed that many who suffer from Alzheimer's disease and dementia have vitamin B12 deficiencies. Liquid vitamin B12 may aid these patients by quickly boosting the level of this vitamin in the body. Taking concentrated vitamin B12 is thought to decrease the risk of such disorders in the elderly.

Liquid vitamin B12 is also used by some individuals who take herbal supplements or medications for mood disorders. Many people have reported that taking this form of the vitamin in conjunction with other supplements increases the effect. It is also often used by vegans, those with who suffer from high cholesterol due to an amino acid deficiency, those who wish to enhance nutrient retention, and those with gastronomical problems.

There is some question over whether liquid vitamin B12 is as effective as vitamin B12 injections. While side effects are rare, they do occur in some. If someone taking any form of B12 experiences unexplainable symptoms, a physician should be contacted quickly. Those who drink alcohol on a regular basis, or who take over-the counter or prescription medications, vitamins, or herbal supplements should discuss liquid vitamin B12 with a physician or pharmacist before use, as drug interactions can occur.