Its B12 Methylcobalamin that Melody mentioned, it helps to repair damaged nerves, its the active form of b12, we can't buy the supplement form in Australia so its either take b12 Cynocobalamin supplements or shots of hydroxocobalamin, which will still does the job but takes longer to build up stores, the best one is Methylcobalamin if you can get your hands on it though.
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I am sure others will be along shortly to help you with IVIG.question.