Baclofen is not addictive in the conventional medical use of the word. Tolerance, dose escalation, and drug cravings do not occur among recipients. Physical dependence is a feature of medium to long term use in all users - IT IS VERY IMPORTANT TO NEVER STOP TAKING BACLOFEN ABRUPTLY, OR TO TAPER OFF TOO RAPIDLY.
Baclofen is a very safe drug and serious injuries/fatalities due to misuse are extremely rare - even in the case of massive, deliberate overdose. That said, it is possible to hurt yourself by taking too much baclofen at once.