A panic attack is a hell of an experience - literally. In my case, outter help - like other people telling me to calm down and that everything is okay - didn't do much help. I've had one "big" attack in my life, that was my first and the most powerful one. Later on, though, I experienced "smaller", less-horrifiing attacks (same sypthoms, but not so strong and didn't last long (usually about 20 minutes, my first panic attack lasted 3 hours and I've had after-effects for about 3 months...)). Panic attack works differently in every people experiencing it. If you've had some attacks before, you probably know the sypthoms "telling you" that an attack is on the way. In this state, it's important to find something that helps you relax - taking long, deep breaths (it also helps to maintain a calm heartrate), walking, getting some fresh air, drinking a tea, meditating, whatever helps. If the attack itself did happen, it is hard to focus on these calming things because of the flight-or-fight drive. Find a situation or place you feel confortable in - tell your parents/co-workers/friends that you need some help, if you need outter help, or find a place you can feel at ease alone - like a tea-kitchen at work, for example. Take long, deep breaths, and don't try to fight the drive - don't try to shoo the feeling away. It will wash through you, it's an overwhelming experience, but I found fighting it making it much worse. It'll stop in a few minutes. Keep on taking deep breaths, if it happens at work, try to take small breaks - just a few minutes - to relax. Find some music. Something that makes you feel better, that helps you relax in tense situation (even cat videos can help... really, anything that fits you). The attack itself should completely end within an hour at most. The two things you shouldn't do: don't fight the attack, and don't be afraid of experiencing a panic attack. If you already had one, the fear itself from happening can trigger another. These steps are hard to take alone, and if you just had your very first, or few attacks, I think you definently should ask the help of a professional. Panic attacks can occour from emotional (overwhelming stress) or neurological source, and if it calms you, you should definently have it checked out.