Xanax is a depressant, used primarily for short term relief of mild to moderate anxiety, nervous tension, acute stress, and panic attacks. 

Xanax is only approved by the FDA for up to 8 weeks of use and it is only approved for only 4 weeks of use in Great Britain. This is because it is extremely addictive. The greater the dose taken, the faster one becomes dependant. If one uses these drugs long term, the body will develop tolerance for the drugs, and larger doses will be needed to achieve the same initial effects. In addition, continued use can lead to physical dependence and - when use is reduced or stopped the body goes through.

The withdrawal symptoms from Xanax and other benzodiazepines are quite similar, with the exception that Xanax has a much higher incidence of panic attack and a bereavement type of emotional liability that is singularly more severe.

Xanax and other benzo�s are depressants. They sometimes referred to as minor tranquilizers. The effect on the mind is very similar to that of alcohol. It should be emphasized again that all minor tranquilizers combine with each other or with other central nervous system depressants�such as barbiturates, antidepressants, neuroleptics, lithium, and alcohol�with a potentially fatal result. While they can be lethal when taken alone, they are especially dangerous in combination with these other drugs. A large percentage of drug-related emergency room visits involve minors tranquilizers. All of the minor tranquilizers impair mental alertness and physical coordination and can dangerously compromise mechanical performance, such as automobile driving. 

Here are the withdrawal symptoms from Benzo�s and the thing to keep in mind is that withdrawals can last for up to one year. 

Single asterisk are symptoms that are common, and occur in most people. The double asterisk indicates symptoms that occur to some degree or another, at one time or another, in virtually every person experiencing benzodiazepine withdrawal.

 Psychological symptoms: anxiety** (including panic attacks), depression**, insomnia*, derealization/depersonalization* (feelings of unreality/detachment from self), abnormal sensitivity sensory stimuli* (such as loud noise or bright light), obsessive negative thoughts*, (particularly of a violent and/or sexual nature) rapid mood changes* (including especially outbursts of anger or rage), phobias* (especially agoraphobia and fear of insanity), dysphoria* (loss of capacity to enjoy life; possibility a combination of depression, anxiety, and derealization/depersonalization), impairment of cognitive functioning*, suicidal thoughts*, nightmares, hallucinations, psychosis, pill cravings. Note that it is far more common to fear psychosis than it is to actually experience it. Physical Symptoms: muscle tension/pain**, joint pain*, tinnitus*, headaches*, shaking/tremors*, blurred vision* (and other complications related to the eyes), itchy skin* (including sensations of insects crawling on skin), gastrointestinal discomfort*, electric shock sensations*, paresthesia* (numbness and pins and needles, especially in extremities), fatigue*, weakness in the extremities (particularly the legs)*, feelings of inner vibrations* (especially in the torso), sweating, fluctuations in body temperature, difficulty in swallowing, loss of appetite, "flu like" symptoms, fasciculations (muscle twitching), metallic taste in mouth, nausea, extreme thirst (including dry mouth and increased frequency of urination), sexual dysfunction (or occasional increase in libido), heart palpitations, dizziness, vertigo, breathlessness. 

What has become clinically apparent with Xanax which appears to be somewhat different than the other benzodiazepines is that the patients ability to self-detox or be able to be gradually tapered off of the medication is markedly more difficult. Thusly, once the physiologic dependence has occurred with Xanax, the ability of the patient to discontinue use successfully on their own is quite low, and medical assistance becomes of significant necessity in the majority of cases 

Links 

whatmeds.com

psyweb.com

breggin.com