A panic attack sufferer requires support, reassurance, and not criticism. Saying something like 'you can easily go through this', or 'focus on your breathing pattern and live in the present', can work wonders to relieve her discomfort. Your words should convey that you are by her side and ready to help in whatever way you can. You need to take the person seriously, and make her aware that you really care for her health. Try to understand her apprehensions, and make her realize that panic attacks are no threat to her health, and it's just a temporary phase that will soon go away.
Disclaimer: The information provided in this article is solely for educating the reader. It is not intended to be a substitute for the advice of a medical expert.