What to advise patients who request B12 (Cobalamin) injections without a diagnosed deficiency?

What to Tell Patients Requesting B12 Injections Without Deficiency

Patients without documented B12 deficiency should not receive B12 injections, as there is no medical indication, no proven benefit, and they should be counseled that supplementation is only indicated for confirmed deficiency (serum B12 <150 pmol/L or <180 pg/mL) or malabsorption conditions. 1

Key Counseling Points

Explain the Medical Indications

• B12 injections are medically indicated only for patients with documented deficiency (B12 <150 pmol/L) or specific malabsorption conditions including pernicious anemia, ileal resection >20 cm, or post-bariatric surgery 1
• Without deficiency, there is no evidence that B12 injections provide health benefits for energy, mood, weight loss, or general wellness 2
• The FDA label specifically warns against "indiscriminate administration" of B12, as it may mask other underlying conditions like folate deficiency 3

Address Common Misconceptions

• Many patients believe B12 injections will boost energy or improve well-being, but these benefits only occur when correcting an actual deficiency 2
• Normal B12 levels (typically >170-200 pmol/L) indicate adequate stores, and additional supplementation provides no added benefit 1
• If the patient has nonspecific symptoms like fatigue, investigate other causes rather than empirically treating with B12 1

Offer Appropriate Alternatives

If borderline levels (140-200 pmol/L):

• Check methylmalonic acid (MMA) levels; if MMA >271 nmol/L, this confirms functional deficiency and warrants treatment 1
• Also measure homocysteine; levels >10-15 μmol/L may indicate metabolic B12 deficiency requiring treatment 1

If truly normal levels:

• Reassure the patient that their B12 status is adequate 1
• Investigate other causes of their symptoms (thyroid function, iron studies, vitamin D, depression screening, sleep disorders) 2
• Explain that the WHO recommends only 2.4 mcg daily for healthy adults, easily obtained through diet 4

Discuss Risks and Costs

• While B12 injections are generally safe, they involve unnecessary medicalization, clinic visits, injection site reactions, and rare complications 5
• The economic burden is significant—Ontario's health system identified potential savings of $14.2 million over 5 years by avoiding unnecessary injections 6
• Patients who insist on self-administering injections without medical supervision report lower perceived safety in primary care and may be engaging in unsafe health behaviors 7

Clinical Pitfalls to Avoid

• Never prescribe B12 injections "just to try it" or to appease patients—this reinforces inappropriate health-seeking behavior and medicalizes normal states 3, 7
• Do not order B12 testing in asymptomatic patients without risk factors—this leads to overdiagnosis and unnecessary treatment 1
• Avoid the trap of treating borderline-low B12 without checking MMA or homocysteine—many borderline levels are clinically insignificant 1
• Remember that folic acid supplementation can mask B12 deficiency—always check B12 status before starting folate 3

Documentation Strategy

• Document the patient's request, your explanation of lack of indication, and the patient's understanding 7
• If the patient has symptoms, document your alternative diagnostic workup 2
• Note that you explained the difference between treating deficiency versus supplementing normal levels 1
• This protects against future claims that deficiency was "missed" while establishing appropriate boundaries 7

When to Reconsider

Only order B12 testing if:

• Patient has risk factors: age >65, strict vegan diet, malabsorption conditions (Crohn's disease, celiac disease), gastric surgery, chronic PPI or metformin use 1
• Neurological symptoms suggestive of B12 deficiency: paresthesias, gait disturbance, cognitive impairment 1
• Macrocytic anemia on CBC 3
• Patient develops documented deficiency on future testing 1