From the Guidelines
The recommended monthly dosage for B12 injection is 1 mg intramuscularly administered every 2-3 months for life, as stated in the British Obesity and Metabolic Surgery Society guidelines 1. This dosage is specifically recommended for patients with vitamin B12 deficiency and no neurological involvement.
- For patients with vitamin B12 deficiency and possible neurological involvement, the initial treatment involves more frequent injections, with hydroxocobalamin 1 mg intramuscularly administered on alternate days until there is no further improvement, then hydroxocobalamin 1 mg intramuscularly administered every 2 months 1.
- The British Obesity and Metabolic Surgery Society guidelines also recommend routine supplementation with vitamin B12 intramuscular injections every 3 months for patients who have undergone certain bariatric surgery procedures, such as sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), or malabsorptive procedures like biliopancreatic diversion with duodenal switch (BPD/DS) 1. However, the most recent and highest quality study, which is the British Obesity and Metabolic Surgery Society guidelines 1, recommends a dosage of 1 mg intramuscularly administered every 2-3 months for life.
- It is essential to note that vitamin B12 deficiency should be treated immediately, and urgent specialist advice should be sought from a neurologist and haematologist if there is possible neurological involvement 1.
- Regular monitoring of B12 levels is recommended to ensure the dosage is appropriate.
- Patients with certain conditions like pernicious anemia, malabsorption disorders, or those who've had gastric surgery may require lifelong B12 supplementation.
- Side effects are rare but may include pain at the injection site, mild diarrhea, or itching.
From the Research
Monthly Dosage for B12 Injection
- The recommended monthly dosage for B12 injection is 1000 micrograms of cyanocobalamin 2.
- This dosage is considered necessary to meet metabolic requirements in many patients, with 5 or 6 biweekly injections for loading and once-a-month for maintenance 2.
- Other studies suggest that high oral doses of B12 (1000 mcg and 2000 mcg) may be as effective as intramuscular administration in achieving haematological and neurological responses 3, 4.
- However, the specific monthly dosage for B12 injection is not explicitly stated in these studies, which focus on the comparison between oral and intramuscular administration.
- It is worth noting that the route of administration, whether intramuscular or oral, may not be the most important factor in treating vitamin B12 deficiency, as long as the dosage is adequate 5.