Contact your GP if you experience: Unexpected symptoms after starting B12 supplementation, including persistent skin reactions, gastrointestinal disturbance, or mild allergic manifestations Neurological symptoms such as significant tingling, numbness, weakness, or balance problemsthese may indicate B12 deficiency paradoxically, or alternative neurological conditions requiring assessment Unexplained fatigue or malaise that develops or worsens despite supplementation Concerns about medication interactions , particularly if taking metformin, proton pump inhibitors, or other medications affecting B12 metabolism [2] [4] Seek emergency medical attention (call 999) if you develop signs of a severe allergic reaction following B12 injection, including facial swelling, difficulty breathing, or widespread urticaria
Typical daily range: 400 mcg (0.4 mg) 1,200 mcg (1.2 mg) total blend once daily, raised gradually across the cycle
Sometimes this may make homocysteine levels look normal on testing, despite issues with methylation
Be careful to avoid air bubbles
During rapid correction of severe anemia, potassium may need monitoring in some higher-risk patients
Hypokalaemia (low blood potassium) in the first weeks of loading-dose treatment in patients who started severely deficient
