I'm glad you said "on and off", otherwise I might suggest that you taking them for years perhaps suggest addiction (I'm just teasing)Some muscle relaxers require a prescription and are a controlled substance. Muscle relaxants are a commonly abused substance. People with a history of drug or addiction should not use muscle relaxers and should never mix them with alcohol. The pain relief muscle relaxants provide can become addictive to those in chronic pain. Also, when someone's body becomes used to the daily intake of a muscle relaxers you can become dependent on them to function. You could experience withdrawal symptoms when you stop taking them.