how often can b12 injections be taken Long Does It Take For To Work? How Can Vitamin B12 Shots

You likely wont see any negative side effects from too much Vitamin B-12

A clinical series published in the Journal of Clinical Medicine found that patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) who received intermittent intravenous saline infusions over a 9-week period showed beneficial effects in managing symptoms of dysautonomia and postural orthostatic tachycardia syndrome (POTS)

These side effects usually go away fairly quickly

J Clin Endocrinol Metab 100:31123117

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Peripheral neuropathy may progress to affect the sensation and function of nerves in the hands, arms, abdomen, and face