Getting an injection into the carpal tunnel is not without risks. But the probability is low that the needle would poke the nerve, and it's not likely the medication would be accidently injected directly into the median nerve. If either of these two problems were to happen, there's a chance you might experience pain, numbness, or a sensation of pins and needles in the thumb and fingers where the nerve goes. These symptoms could continue to be felt for several weeks after the injection. But it's not likely you would end up with lasting problems.