Injecting substances can expose individuals that use injection drugs to serious harm, but understanding the difference between safer and more harmful sites can help reduce these potential dangers. Here's a breakdown of How to Give B12 Injections at Home to Yourself PA Relief What Can Happen If an Injection Is Given Wrongly Into a Vein?, Giving an injection the wrong wayespecially into a vein when it wasnt meant to go therecan cause several problems:, Pain or burning at what happens when you hit a vein during injection?