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General Information

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Use

WHY is this medicine prescribed?

Cyanocobalamin injection is used to treat and prevent a lack of vitamin B12 that may be caused by any of the following: pernicious anemia (lack of a natural substance needed to absorb vitamin B12 from the intestine); certain diseases, infections, or medications that decrease the amount of vitamin B12 absorbed from food; or a vegan diet (strict vegetarian diet that does not allow any animal products, including dairy products and eggs). Lack of vitamin B12 may cause anemia (condition in which the red blood cells do not bring enough oxygen to the organs) and permanent damage to the nerves. Cyanocobalamin injection also may be given as a test to see how well the body can absorb vitamin B12. Cyanocobalamin injection is in a class of medications called vitamins. Because it is injected straight into the bloodstream, it can be used to supply vitamin B12 to people who cannot absorb this vitamin through the intestine.

HOW should this medicine be used?

Cyanocobalamin comes as a solution (liquid) to be injected into a muscle or just under the skin. It is usually injected by a healthcare provider in an office or clinic. You will probably receive cyanocobalamin injection once a day for the first 6-7 days of your treatment. As your red blood cells return to normal, you will probably receive the medication every other day for 2 weeks, and then every 3-4 days for 2-3 weeks. After your anemia has been treated, you will probably receive the medication once a month to prevent your symptoms from coming back.

Cyanocobalamin injection will supply you with enough vitamin B12 only as long as you receive injections regularly. You may receive cyanocobalamin injections every month for the rest of your life. Keep all appointments to receive cyanocobalamin injections even if you feel well. If you stop receiving cyanocobalamin injections, your anemia may return and your nerves may be damaged.

Are there OTHER USES for this medication?

Cyanocobalamin injection is also sometimes used to treat inherited conditions that decrease the absorption of vitamin B12 from the intestine. Cyanocobalamin injection is also sometimes used to treat methylmalonic aciduria (an inherited disease in which the body cannot break down protein) and is sometimes given to unborn babies to prevent methylmalonic aciduria after birth. Talk to your doctor about the possible risks of using this drug for your condition.

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

Special

What SPECIAL PRECAUTIONS should I follow?

Before using cyanocobalamin injection,

What SPECIAL DIETARY instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

What should I do IF I FORGET to take a dose?

If you miss an appointment to receive a cyanocobalamin injection, call your doctor as soon as possible.

Side Effects

What SIDE EFFECTS can this medicine cause?

Cyanocobalamin injection may cause side effects. Tell your doctor if either of these symptoms is severe or does not go away:

Some side effects can be serious. The following symptoms are uncommon, but if you experience any of them, call your doctor immediately:

Cyanocobalamin injection may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

Overdose

What should I do in case of OVERDOSE?

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at http://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

Storage

What should I know about STORAGE and DISPOSAL of this medication?

Your doctor will store this medication in his or her office.

Miscellaneous

What OTHER INFORMATION should I know?

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your body's response to cyanocobalamin injection.

Keep a written list of all of the prescription and nonprescription (over-the-counter) medicines, vitamins, minerals, and dietary supplements you are taking. Bring this list with you each time you visit a doctor or if you are admitted to the hospital. You should carry the list with you in case of emergencies.

¶ This branded product is no longer on the market. Generic alternatives may be available.

This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.

The American Society of Health-System Pharmacists, Inc. represents that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information is not a substitute for medical care.

AHFS® Patient Medication Information Copyright, 2025. The American Society of Health-System Pharmacists®, 4500 East-West Highway, Suite 900, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.

Last Reviewed: September 1, 2010.