Vitamin B12 Injections Side Effects

For most people considering taking vitamin B12 injections, side effects are generally not serious. However, in certain instances serious side effects may occur.

Vitamin B12 Injections

Physicians give Vitamin B12 injections, also known as cobalamin or cyanocobalamin injections, to patients that are suffering from anemia, fatigue or other symptoms of vitamin B12 deficiency. Patients that have pernicious anemia require lifelong vitamin B12 injections and may want to consider dietary changes for B12 deficincy. These injections are sometimes very painful as they are given deep under the skin, known as a deep subcutaneous injection, or into a muscle, called an intramuscular injection.

Common Side Effects of Injections of Vitamin B12

There are many side effects that patients may experience from injections of vitamin B12. The more common side effects include:

• Mild diarrhea
• Upset stomach
• Nausea
• A feeling of pain and a warm sensation at the site of the injection
• A feeling, or a sense, of being swollen over the entire body
• Headache
• Joint pain

If any of these side effects become severe or troublesome, let your doctor know right away.

Vitamin B12 Injections: Side Effects That are Uncommon and Serious

Vitamin B12 injections can result in serious side effects. Although this is a relatively rare occurrence, anyone taking vitamin B12 injections should be aware of the possibility. Call your doctor immediately if you experience any of the following side effects.

• A rapid heartbeat
• Heart palpitations
• Chest pain
• A feeling of tightness in the chest
• Rapid weight gain
• Muscle weakness
• Muscle pain
• Muscle cramps
• A feeling of extreme thirst
• Frequent urination
• Leg pain
• A sense of confusion
• Numbness
• Dizziness
• A tingling sensation
• Difficulty breathing
• Difficulty swallowing
• Shortness of breath with mild exertion or when lying down
• Unusual coughing
• Unusual wheezing
• A feeling of extreme tiredness or fatigue
• Swelling of the extremities including hands, arms, lower legs, feet or ankles
• Redness, pain or a feeling of warmth in one leg
• Tenderness or swelling in one leg
• A red skin color on the face
• A red skin color anywhere on the body
• Hives
• Itching
• Skin rash

Other side effects of vitamin B12 injections may also occur. If you experience anything unusual while taking B12 injections let your doctor know as soon as possible.

What You Need to Tell Your Doctor Before Starting Vitamin B12 Injections

Before starting vitamin B12 injections make sure to tell your doctor if you are pregnant, lactating or have any of the following conditions.

• Leber’s Disease
• Kidney disease
• Liver disease
• An infection
• Iron deficiency
• Folic acid deficiency
• Receiving any treatment that has an effect on bone marrow
• Taking any medication that has an effect on bone marrow
• An allergy to cobalt or any other medication, vitamin, dye, food or preservative

Leber’s Disease

Anyone that has or has ever had Leber’s disease should not take vitamin B12 injections. Leber’s disease, also known as LHON, is hereditary optic neuropathy which causes slow painless vision loss. The vision loss occurs first in one eye and then in the other eye.

Severe Allergic Reaction

Although a severe allergic reaction is very rare, they have occurred. This type of allergic reaction can be life threatening. Medical professionals and researchers are not clear if the allergic reaction is caused by the preservatives or other substances found in the injection solution, or to the vitamin itself.

Prescription and Nonprescription Drug Interactions

It is important to let your doctor know all of the prescription and over-the-counter medications that you take that are prescribed by other doctors. You also need to include any herbal products, vitamins, minerals and nutritional supplements that you take on a regular basis. The following is an incomplete list of medications and other substances that can interact with vitamin B12 injections.

• Alcohol
• Antibiotics such as chloramphenicol
• Chloramphenicol
• Cimetidine
• Colchicine
• Colchicine
• Folic acid
• Methotrexate (Rheumatrex or Trexall)
• Neomycin
• Para-aminosalicylic acid (Paser)
• Phenobarbital
• Phenytoin
• Potassium supplements
• Primidone
• Pyrimethamine (Daraprim)
• Vitamin products

Always check with the doctor that has prescribed the vitamin B12 injections before adding any new medication.

Conclusion

For anyone taking vitamin B12 injections, serious side effects rarely occur. Being aware of dangerous drug interactions and knowing what to watch for regarding side effects makes taking vitamin B12 injections that much safer.

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