Rebound Anxiety is anxiety that is caused by stopping taking some form of medication. It is most common to get rebound anxiety from tranquilisers such as benzodiazepines (see Does Xanax Work for Anxiety) and also anti-depressant SSRI’s such as Prozac and Celexa.
Rebound anxiety is thought to be caused by the fact that many drugs (including benzodiazepines and SSRI’s) achieve their goal by fooling the brain into believing that levels of certain brain chemicals are higher than they really are. The brain then cuts down on its own production of said chemicals leaving you deficient unless you keep taking the drugs.
The answer is to not get hooked in the first place. But failing that, it is best to withdraw slowly, to taper off from the drugs. This will allow your body to compensate by making more and more of its own chemicals.
That is why medication alone is never the answer to anxiety and panic attacks, only a symptomatic cure and one with major downsides.