Why do you need to taper off of zanaflex (tizanidine) if it is not addictive and has no rebound effects?

It can have rebound: If therapy needs to be discontinued, particularly if dose was hi (20-36 mg/day) for many weeks or if on pain meds too, dose should be decreased slowly (2 mg to 4 mg per day) to minimize the risk of withdrawal and rebound hypertension, tachycardia, and hypertonia. Some are less concerned than others w/ safety. It's up to you. Best wishes.