April 29, 2017
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Side Effects


The incidence of adverse experiences described in the Table below are based on data from a short-term clinical trial in vitamin B12 deficient patients in hematologic remission receiving Nascobal (Cyanocobalamin, USP) Gel for Intranasal Administration (N=24) and intramuscular vitamin B12 (N=25). In the pharmacokinetic study comparing Nascobal (cyanocobalamin) Nasal Spray and Nascobal (cyanocobalamin) Nasal Gel, the incidence of adverse events was similar.

Table. Adverse Experiences by Body System, Number of Patients and Number of Occurrences by Treatment Following Intramuscular and Intranasal Administration of Cyanocobalamin.

    Number of Patients (Occurrences)
Body System Adverse Experience Vitamin B12
Nasal Gel,
500 mcg
Vitamin B12 ,
100 mcg
Body as a Whole Asthenia 1 (1) 4 (4)
Back Pain 0 (0) 1 (1)
Generalized Pain 0 (0) 2 (3)
Headache 1 (2)* 5 (11)
Infectiona 3 (4) 3 (3)
Cardiovascular System Peripheral Vascular Disorder 0 (0) 1 (1)
Digestive System Dyspepsia 0 (0) 1 (2)
Glossitis 1 (1) 0 (0)
Nausea 1 (1)* 1 (1)
Nausea & Vomiting 0 (0) 1 (1)
Vomiting 0 (0) 1 (1)
MusculoskeletalSystem Arthritis 0 (0) 2 (2)
Myalgia 0 (0) 1 (1)
Nervous System Abnormal Gait 0 (0) 1 (1)
Anxiety 0 (0) 1 (1)*
Dizziness 0 (0) 3 (3)
Hypoesthesia 0 (0) 1 (1)
Incoordination 0 (0) 1 (2)*
Nervousness 0 (0) 1 (3)*
Paresthesia 1 (1) 1 (1)
Respiratory Dyspnea 0 (0) 1 (1)
System Rhinitis 1 (1)* 2 (2)
a Sore throat, common cold
* There may be a possible relationship between these adverse experiences and the study drugs. These adverse experiences could have also been produced by the patient's clinical state or other concomitant therapy.

The intensity of the reported adverse experiences following the administration of Nascobal (Cyanocobalamin, USP) Gel for Intranasal Administration and intramuscular vitamin B12 were generally mild. One patient reported severe headache following intramuscular dosing. Similarly, a few adverse experiences of moderate intensity were reported following intramuscular dosing (two headaches and rhinitis; one dyspepsia, arthritis, and dizziness), and dosing with Nascobal (Cyanocobalamin, USP) Gel for Intranasal Administration (one headache, infection, and paresthesia).

The majority of the reported adverse experiences following dosing with Nascobal (Cyanocobalamin, USP) Gel for Intranasal Administration and intramuscular vitamin B12 were judged to be intercurrent events. For the other reported adverse experiences, the relationship to study drug was judged as “possible” or “remote”. Of the adverse experiences judged to be of “possible” relationship to the study drug, anxiety, incoordination, and nervousness were reported following intramuscular vitamin B12 and headache, nausea, and rhinitis were reported following dosing with Nascobal (Cyanocobalamin, USP) Gel for Intranasal Administration.

The following adverse reactions have been reported with parenteral vitamin B12:

Generalized: Anaphylactic shock and death (See WARNINGS and PRECAUTIONS).

Cardiovascular: Pulmonary edema and congestive heart failure early in treatment; peripheral vascular thrombosis.

Hematological: Polycythemia vera.

Gastrointestinal: Mild transient diarrhea.

Dermatological: Itching; transitory exanthema.

Miscellaneous: Feeling of swelling of the entire body.

Read the Nascobal (cyanocobalamin) Side Effects Center for a complete guide to possible side effects


Drug/Laboratory Test Interactions

Persons taking most antibiotics, methotrexate or pyrimethamine invalidate folic acid and vitamin B12 diagnostic blood assays.

Colchicine, para-aminosalicylic acid and heavy alcohol intake for longer than 2 weeks may produce malabsorption of vitamin B12.

Read the Nascobal Drug Interactions Center for a complete guide to possible interactions

This monograph has been modified to include the generic and brand name in many instances.

Last reviewed on RxList: 12/12/2016

Side Effects

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