muscle spasm
"Did not react to this well. Had a concussion and occipital neuralgia diagnosis after a car accident and was prescribed this. I do not take meds well so not surprised that this wasn't good for me. I had an immediate reaction of  extreme shivering and body shaking that I had to deal with until the meds faded. Did not reduce head tension or pain and just made me really scared by my bodies reaction. I never took another."