What is the typical syringe size for vitamin B12 (cobalamin) injections?

Vitamin B12 Injection Syringe Size

For vitamin B12 (cobalamin) injections, a 1-mL syringe with a 26- to 27-gauge needle with a half-inch length is the recommended standard. 1

Administration Route and Needle Selection

• Vitamin B12 injections are typically administered via intramuscular (IM) or subcutaneous routes, as indicated on FDA-approved cyanocobalamin formulations 2

• For subcutaneous injections:

  • Use a 5/8-inch, 23-25 gauge needle 1
  • Inject at a 45-degree angle into the thigh of infants or upper-outer triceps area in persons older than 12 months 1

• For intramuscular injections:

  • Needle size should be appropriate to reach muscle mass without affecting underlying structures 1
  • For adults: 1-1½ inches, 22-25 gauge needle is recommended for deltoid muscle administration 1
  • For infants: 7/8-1 inch, 22-25 gauge needle is sufficient for thigh muscle injection 1

Vitamin B12 Dosing and Administration

• Standard vitamin B12 formulations are available as 1,000 mcg/mL in multiple dose vials 2

• For vitamin B12 deficiency treatment:

  • Initial treatment for severe deficiency: 1,000 mcg intramuscularly three times a week for 2 weeks 3
  • Maintenance treatment: 1,000 mcg intramuscularly every 2-3 months 3, 4
  • For neurological involvement: 1,000 mcg intramuscularly on alternate days until symptoms improve 4

• For patients with malabsorption (pernicious anemia, ileal resection, bariatric surgery):

  • Monthly vitamin B12 injections of 1,000 mcg are recommended 4
  • Patients with more than 20 cm of distal ileum resected should receive monthly injections for life 4

Special Considerations

• For patients with thrombocytopenia (platelet count 25-50 × 10⁹/L), smaller gauge needles (25-27G) are recommended with prolonged pressure (5-10 minutes) at the injection site 4
• The deltoid muscle is the preferred site for adult vitamin B12 injections 1
• Always aspirate before injection to ensure the needle is not in a blood vessel 1
• If blood appears in the needle hub, withdraw the needle, discard the syringe appropriately, and select a new injection site 1

Alternative Administration Routes

• While intramuscular is the traditional route, evidence suggests oral supplementation (1,000-2,000 mcg daily) may be therapeutically equivalent to parenteral therapy for many patients 5, 6
• Intranasal administration has shown promise in pediatric patients as an alternative to painful injections 7

Remember that proper documentation of vitamin B12 injections is essential, including the contents, informed consent, and administration details 1.