From the FDA Drug Label
Pernicious Anemia Parenteral vitamin B12 is the recommended treatment and will be required for the remainder of the patient's life. A dose of 100 mcg daily for 6 or 7 days should be administered by intramuscular or deep subcutaneous injection. If there is clinical improvement and if a reticulocyte response is observed, the same amount may be given on alternate days for seven doses, then every 3 to 4 days for another 2 to 3 weeks. By this time hematologic values should have become normal This regimen should be followed by 100 mcg monthly for life.
The recommended treatment for pernicious anemia with a positive anti-intrinsic factor (anti-IF) antibody is parenteral vitamin B12. The treatment regimen consists of:
- An initial dose of 100 mcg daily for 6 or 7 days administered by intramuscular or deep subcutaneous injection.
- Followed by 100 mcg on alternate days for seven doses, then every 3 to 4 days for another 2 to 3 weeks.
- Maintenance therapy with 100 mcg monthly for life 1.
From the Research
The recommended treatment for pernicious anemia with a positive anti-intrinsic factor antibody is high-dose oral vitamin B12 supplementation at 1000 μg daily, as it has been shown to be an effective alternative to intramuscular injections in correcting vitamin B12 deficiency and improving clinical outcomes. This approach is supported by a recent prospective cohort study published in 2024 2, which demonstrated that oral vitamin B12 supplementation at 1000 μg daily can effectively improve vitamin B12 deficiency in patients with pernicious anemia, with significant improvements in plasma vitamin B12, homocysteine, and methylmalonic acid concentrations.
The use of oral vitamin B12 supplementation is also consistent with the findings of a 2016 review published in Frontiers in Medicine 3, which suggested that oral vitamin B12 replacement at 1000 μg daily can be an effective alternative to intramuscular injections. While intramuscular injections have traditionally been the gold standard for treating pernicious anemia, the evidence suggests that high-dose oral vitamin B12 supplementation can be a viable and effective treatment option for many patients.
Key benefits of oral vitamin B12 supplementation include:
- Convenience and ease of administration
- Reduced risk of injection-related complications
- Potential for improved patient adherence and quality of life
- Effective correction of vitamin B12 deficiency and improvement in clinical outcomes
Regular monitoring of complete blood counts, reticulocyte response, and vitamin B12 levels is still important to ensure adequate treatment, and patients should also be monitored for other autoimmune conditions, as pernicious anemia often occurs as part of autoimmune polyglandular syndromes. Overall, the evidence supports the use of high-dose oral vitamin B12 supplementation as a first-line treatment option for pernicious anemia with a positive anti-intrinsic factor antibody.