Ativan and Xanax were both found to be more effective than placebo, with Xanax being slightly more effective in later weeks of the study; however, another reflection of the two drugs for anxiety showed both drugs to be with Ativan being more effective. The primary differentiation between Ativan and Xanax is that Ativan leaves a patient's system more quickly, therefore, reducing the chance of toxicity or side effects. Some side effects of both these drugs include sedation, dizziness, weakness, instability, and memory problems.