Can too much vitamin B12 make you light headed? What you need to know
                                
                                
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                                    3 min read                                
                            
                                While vitamin B12 is a water-soluble vitamin and generally safe, high doses, especially through injections, have been reported to cause side effects including dizziness and headaches in some individuals. The body excretes any excess, making toxicity rare, but large supplemental doses can temporarily overwhelm the system.