Xanax withdrawal symptoms?

I agree with masso.
I'd add: shakes, feelings of despair, worrying if you'll be okay. It's not a good feeling at all.
You MUST not discontinue use abruptly at all costs if you've been on this medication for some time. You must titrate very slowly, and preferably under supervision of a health care professional.

Headaches
Blurred vision
Muscle pain
Tremors
Diarrhea
Numb fingers
Sensitivity to light and sound
Loss of appetite
Insomnia
Heart palpitations
Sweating
Anxiety
Panic
Paranoia
Seizures

In order to lessen and avoid withdrawals you must discontinue the use gradually under medical supervision.