What is B-12: Uses, Warnings & Interactions

Updated May 14, 2025  •  Published Dec 30, 2020

B-12 overview

BRAND NAMES:

  • Vitamist B12-500, B-12-SL, Mason Natural B-12, Nature's Blend B12, Sundown Naturals B12, Twelve Resin-K, Vitamist B12-500, Optimum Vitamin B-12, PharmAssure Vitamin B-12, Sundown Naturals B12, Twelve Resin-K, Vitamin B12 AvPak, Vitamist B12-500

Generic Names:

  • Vitamin B-12

Uses:

  • Supplies your body with vitamin B12. You might need a vitamin B12 supplement if your body has trouble using the vitamin B12 in the food you eat. You also might need vitamin B12 if you are a vegetarian, if you have had part of your stomach removed, or for other reasons. Prevents pernicious anemia, a blood problem caused by a lack of vitamin B12. Cyanocobalamin is another name for vitamin B12.

Therapeutic Classes:

  • Nutritive Agent, Vitamin B Combination

Forms:

  • Capsule, Tablet, Long Acting Tablet, Lozenge, Dissolving Tablet, Liquid, Spray

How it’s taken:

  • By mouth

What is B-12 used for?

What form(s) does B-12 come in

  • Capsule

  • Tablet

  • Long Acting Tablet

  • Lozenge

  • Dissolving Tablet

  • Liquid

  • Spray

What are common B-12 doses?

  • Bottle 30 Tablets Sublingual

  • Bottle 40 Tablets Sublingual

  • Bottle 100 Tablets

  • Bottle 90 Tablets

  • Bottle 110 Tablets

  • Bottle 50 Tablets

  • Bottle 50 Lozenge

  • Bottle 90 Capsules

  • Bottle 100 Tablets Sublingual

  • Bottle 110 Tablets Extended Release

  • Bottle 150 Tablets Disintegrating

  • Bottle 160 Tablets Extended Release

  • Bottle 200 Tablets Sublingual

  • Bottle 60 Tablets

  • Bottle 75 Tablets Sublingual

  • Bottle 110 Tablets Sublingual

  • Bottle 40 Lozenge

  • Bottle 60 Tablets Sublingual

  • Bottle 60 Capsules

Common B-12 prescriptions

  • B-12
    100 tablets bottle

  • B-12
    100 tablets sublingual bottle

  • B-12
    110 tablets extended release bottle

  • B-12
    110 tablets sublingual bottle

  • B-12
    130 tablets bottle

  • B-12
    50 tablets bottle

  • B-12
    60 tablets bottle

  • B-12
    60 tablets sublingual bottle

  • B-12
    75 tablets sublingual bottle

  • B-12
    1 kit box

How to take B-12

  • Your doctor will tell you how much medicine to use. Do not use more than directed.

  • Oral routeCarefully follow your doctor's instructions about any special diet.

  • Follow the instructions on the medicine label if you are using this medicine without a prescription.

  • Measure the oral liquid medicine with a marked measuring spoon, oral syringe, or medicine cup. You might need to shake the liquid just before you use it. You may mix the oral liquid in some juice if you prefer.

  • Place the lozenge in your mouth or under your tongue and let it melt. Some brands of lozenges can also be swallowed. You might need to hold the medicine in your mouth for 30 seconds before you swallow it. Follow the directions on the medicine label.

  • Place the sublingual tablet under your tongue and let it melt. Some brands can also be swallowed. You might need to hold the medicine in your mouth for at least 30 seconds before you swallow. Follow the directions on the medicine label.

  • Spray the mouth spray on the inside of your cheek. Hold the medicine in your mouth for about 30 sections, then swallow.

  • Swallow the extended-release tablet whole. Do not crush, break, or chew it.

  • Measure the oral liquid medicine with a marked measuring spoon, oral syringe, or medicine cup. You might need to shake the liquid just before you use it. You may mix the oral liquid in some juice if you prefer.

  • Spray the mouth spray on the inside of your cheek. Hold the medicine in your mouth for about 30 sections, then swallow.

  • Follow the instructions on the medicine label if you are using this medicine without a prescription.

  • Place the sublingual tablet under your tongue and let it melt. Some brands can also be swallowed. You might need to hold the medicine in your mouth for at least 30 seconds before you swallow. Follow the directions on the medicine label.

  • Oral routeCarefully follow your doctor's instructions about any special diet.

  • Place the lozenge in your mouth or under your tongue and let it melt. Some brands of lozenges can also be swallowed. You might need to hold the medicine in your mouth for 30 seconds before you swallow it. Follow the directions on the medicine label.

  • Swallow the extended-release tablet whole. Do not crush, break, or chew it.

  • Your doctor will tell you how much medicine to use. Do not use more than directed.

What to do if you miss a dose of B-12

  • Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.

  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.

  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

B-12 contraindications

  • You should not use this medicine if you have had an allergic reaction to vitamin B12 (cyanocobalamin), hydroxycobalamin, or cobalt (a metal).

B-12 warnings

  • Your doctor might need to check your blood at regular visits while you are using this medicine. Be sure to keep all appointments.

  • Make sure your doctor knows if you are pregnant or breast feeding, or if you have liver disease, kidney disease, or Leber€™s disease (an eye disease). Tell your doctor if you have low levels of iron in your blood.

B-12 interactions

  • Make sure your doctor knows if you are also using folic acid (folate) supplements.

  • Your doctor might need to check your blood at regular visits while you are using this medicine. Be sure to keep all appointments.

B-12 side effects

Serious Side Effects

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing

  • Mild skin itching.

Less Serious Side Effects

  • Mild skin itching.

  • Diarrhea.

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