IM & SubQ

Injectable Vitamins: Routes, Forms, Dosage, and Notes

This information is for research purposes only. ALWAYS consult with your healthcare provider.

Water-Soluble Vitamin Injections

Water-soluble vitamins aren’t stored long-term, so injections bypass absorption hurdles. Below is a breakdown of each vitamin’s injectable form, common routes of administration, dosing frequency, and key considerations.

Vitamin Injectable Forms Route(s) Typical Dosage & Frequency Notes
B12 (Cobalamin) Cyanocobalamin; Methylcobalamin IM; SC 1,000–2,000 µg IM or SC weekly–monthly SC often preferred for self-administration
B6 (Pyridoxine) Pyridoxine hydrochloride IM 25–50 mg IM daily–weekly Monitor for neuropathy at high doses
B1 (Thiamin) Thiamine hydrochloride IM 50–100 mg IM daily Used in Wernicke’s encephalopathy protocols
B2 (Riboflavin) Riboflavin sodium phosphate IM 5–20 mg IM daily Rarely injected alone; often in B-complex blends
B3 (Niacin) Niacinamide IM 100–250 mg IM weekly Flush-free; monitor liver enzymes
B5 (Pantothenic) Calcium pantothenate IM 50–100 mg IM weekly Often part of multivitamin injections
B7 (Biotin) D-Biotin IM 1–5 mg IM monthly Low risk; supports skin, hair, nail health
B9 (Folate) Folic acid; Folinic acid IM; IV 1 mg IM weekly or 0.4–1 mg IV daily Folinic acid is preferred in methotrexate therapy
B-Complex Combination of B1–B6, B9, B12 IM; SC; IV 1 mL–5 mL of standard mix IM weekly Check compatibility if infusing IV
Vitamin C Ascorbic acid; Magnesium ascorbate IV; IM 1–10 g IV 1–3× weekly; 250–500 mg IM weekly High-dose IV used in therapeutic drips

Fat-Soluble Vitamin Injections

Fat-soluble vitamins require a lipid carrier or oil base. Injections should be scheduled with meals, though IM is most common to ensure depot formation.

Vitamin Injectable Forms Route(s) Typical Dosage & Frequency Notes
D3 (Cholecalciferol) Oil-based D3 solution IM; SC 100,000–600,000 IU IM every 3–6 months IM gives slow release; monitor serum calcium
A (Retinyl Palmitate) Oil-based retinyl palmitate IM 50,000–200,000 IU IM monthly Rarely used; risk of hypervitaminosis A
E (Tocopherol) Vitamin E injection solution IM 200–400 IU IM weekly Antioxidant support; monitor for coagulopathy
K1 (Phytonadione) Aqueous phytonadione; mixed micelle IM; IV; SC 1–10 mg IM or IV once Newborn prophylaxis; reversal of warfarin effects

Administration Best Practices

  • IM injections:
    • Needle: 22–25 g, 1–1.5 inch for deltoid or gluteal sites
    • Volume per site: ≤ 3 mL
  • SC/SC injections:
    • Needle: 25–30 g, ⅜–⅝ inch in abdomen or thigh
    • Volume per site: ≤ 1 mL; rotate sites
  • IV infusions:
    • Use a compatible diluent (NS or D5W)
    • Infuse over 15–60 minutes based on vitamin concentration
    • Monitor for phlebitis and allergic reactions