What is the treatment for dizziness caused by low vitamin B12 (cobalamin) levels?

Treatment of Dizziness Caused by Low Vitamin B12

For dizziness caused by low vitamin B12, initiate immediate treatment with hydroxocobalamin 1 mg intramuscularly on alternate days until symptoms resolve, then transition to maintenance therapy with 1 mg intramuscularly every 2-3 months for life. 1

Initial Treatment Protocol

The presence of dizziness suggests neurological involvement from B12 deficiency, which requires aggressive initial therapy to prevent irreversible damage. 1, 2

For patients with neurological symptoms (including dizziness):

• Administer hydroxocobalamin 1 mg intramuscularly on alternate days until no further improvement occurs 1
• This intensive regimen is critical because vitamin B12 deficiency allowed to progress for longer than 3 months may produce permanent degenerative lesions of the spinal cord 2
• Continue the alternate-day dosing until dizziness and other neurological symptoms stabilize 1

For patients without neurological involvement:

• Give hydroxocobalamin 1 mg intramuscularly three times weekly for 2 weeks 1, 3
• However, since dizziness represents neurological involvement, this less intensive regimen would be inappropriate 1

Maintenance Therapy

After initial symptom resolution, transition to long-term maintenance:

• Hydroxocobalamin 1 mg intramuscularly every 2 months for life 1, 3
• Some patients may require monthly injections to remain symptom-free, as up to 50% of individuals need more frequent administration ranging from every 2-4 weeks 4
• Never discontinue therapy even if levels normalize, as patients with malabsorption require lifelong supplementation 1

Formulation Selection

Hydroxocobalamin is the preferred formulation over cyanocobalamin or methylcobalamin for several reasons:

• All major guidelines provide specific, evidence-based dosing regimens for hydroxocobalamin 1
• Hydroxocobalamin has superior tissue retention compared to other forms 1
• In patients with renal dysfunction, avoid cyanocobalamin due to potential cyanide accumulation and increased cardiovascular risk (hazard ratio 2.0) 1

Oral Therapy Considerations

While oral B12 can be effective for dietary deficiency, it is insufficient for malabsorption-related deficiency causing neurological symptoms:

• Oral supplementation at 1000-2000 mcg daily may work for dietary deficiency without neurological involvement 1, 5
• However, when dizziness is present, parenteral (intramuscular) therapy is mandatory to ensure adequate tissue delivery 4
• The oral route bypasses only 1-2% of B12 through passive absorption, which is unreliable when neurological damage is occurring 4

Monitoring Strategy

Initial monitoring (first 3 months):

• Check serum B12, homocysteine, and methylmalonic acid every 3 months until stabilization 1
• Monitor for resolution of dizziness and other neurological symptoms clinically 1
• Target homocysteine <10 μmol/L for optimal outcomes 1

Long-term monitoring:

• Once stabilized, check levels annually 1
• Continue monitoring for recurrent neurological symptoms and increase injection frequency if symptoms return 1, 3

Critical Pitfalls to Avoid

Never administer folic acid before treating B12 deficiency - this may mask the anemia while allowing irreversible neurological damage (including worsening dizziness) to progress, potentially precipitating subacute combined degeneration of the spinal cord 1, 2

Do not rely on symptom resolution to discontinue therapy - patients with malabsorption require lifelong treatment regardless of symptom improvement 1, 3

Do not use oral therapy as initial treatment for neurological symptoms - there is currently no evidence that oral/sublingual supplementation can safely and effectively replace injections when neurological involvement is present 4

Do not "titrate" injection frequency based on serum B12 levels - clinical response (resolution of dizziness) is more important than laboratory values, and some patients require more frequent injections despite normal levels 4

Identifying the Underlying Cause

While treating, investigate the cause of deficiency to guide long-term management:

• Pernicious anemia (intrinsic factor antibodies, anti-parietal cell antibodies) 6, 2
• Gastrointestinal pathology (atrophic gastritis, celiac disease, inflammatory bowel disease with >20 cm ileal involvement) 1, 2
• Post-surgical states (gastrectomy, bariatric surgery, ileal resection >20 cm) 1, 2
• Medications (metformin >4 months, PPIs >12 months, colchicine) 6, 2
• Dietary insufficiency (strict vegan/vegetarian diet) 2

Patients with confirmed malabsorption (pernicious anemia, ileal resection, post-bariatric surgery) will require lifelong intramuscular therapy and should be counseled accordingly 1, 2