I take Prozac regularly, but I also have Xanax to take as needed for those panicky, extra anxious times. I definitely take them BEFORE a panic attack and it prevents me from feeling worse. It's pretty fast acting. I have a low dosage, so if you get severe panic attacks, your doctor can prescribe a stronger dose. I usually get pretty sleepy on it, so it's only something I take as needed. It really lets me relax and just rest rather than being all panicky.