Treatment Options for Hypervitaminosis B6 (Elevated Vitamin B6 Levels)
The primary treatment for vitamin B6 toxicity is immediate discontinuation of all vitamin B6 supplementation, followed by symptomatic management of neuropathic pain with appropriate medications such as gabapentin, pregabalin, or duloxetine. 1
Diagnosis of Vitamin B6 Toxicity
- Confirm diagnosis through:
- History of vitamin B6 supplementation
- Elevated plasma pyridoxal phosphate (PLP) levels (normal range: 5-50 μg/L or 20-200 nmol/L)
- In critically ill patients or those with inflammation, measure red cell PLP instead 1
Clinical Presentation of Vitamin B6 Toxicity
Excessive vitamin B6 typically presents with neurological symptoms:
- Sensory neuropathy (most common presentation)
- Painful paresthesias
- Numbness in extremities
- Motor weakness (in severe cases) 2
- Gait disorders 3
- Loss of deep tendon reflexes 1
Treatment Algorithm for Hypervitaminosis B6
Step 1: Immediate Discontinuation
- Stop all vitamin B6 supplements and medications containing vitamin B6 1
- Identify and discontinue over-the-counter supplements that may contain vitamin B6 3
Step 2: Symptomatic Management of Neuropathic Pain
First-line medications:
- Gabapentin: Start at 300 mg once daily, target dose 300-600 mg three times daily
- Pregabalin: Start at 75 mg twice daily, target dose 150-300 mg twice daily
- Duloxetine: 60 mg once daily 1
Second-line options:
- Amitriptyline: Start at 10-25 mg at bedtime, target dose 25-100 mg
- Nortriptyline: Start at 10-25 mg at bedtime, target dose 25-100 mg 1
For refractory cases:
- Consider low-dose naltrexone 1
Step 3: Monitoring and Follow-up
- Response to treatment should be evident within 6-10 days as PLP levels plateau 1
- Monitor vitamin B6 levels until normalization
- Assess improvement in neurological symptoms
- Complete recovery may take weeks to months depending on severity and duration of exposure 4
Risk Factors for Vitamin B6 Toxicity
- Doses greater than 500 mg/day commonly cause toxicity
- Long-term doses as low as 100 mg/day have been associated with spinal cord effects and sensory neuropathy
- Mean duration of intake leading to neurotoxicity: 2.9 ± 1.9 years 1
- Even doses below 50 mg/day cannot be excluded as potential causes of neuropathy with prolonged use 5
Prognosis and Recovery
- Symptoms typically improve after discontinuation of vitamin B6 supplements 6
- Complete clearance of vitamin B6 from the body takes approximately 20-40 days 4
- Recovery time varies based on severity and duration of exposure
- Some patients may have residual neurological deficits if toxicity was severe or prolonged
Prevention of Vitamin B6 Toxicity
- Adhere to safe upper limits for vitamin B6 intake:
- Adults (19-70+ years): 100 mg/day
- Adolescents (14-18 years): 80 mg/day 1
- The Recommended Dietary Allowance (RDA) for vitamin B6 is 1.3 mg/day for most adults 1
Important Caveats
- No statistical correlation between dosage and vitamin B6 blood levels has been established, suggesting individual variability in metabolism 5
- Self-medication with over-the-counter vitamin supplements is a common cause of vitamin B6 toxicity 3
- Vitamin B6 toxicity can occur at doses lower than previously thought with prolonged use 5
- Extreme cases of toxicity have been reported with doses as high as 9.6g/day, resulting in severe sensorimotor neuropathy 2