How to know how long do panic attacks last?

You must be experienced that it can be strenuous for some people to establish when a single panic attack is actually over..Are you aware that sometimes there are a lingering sense of panic, shock, or confusion that lasts for awhile afterward? Are you heard that the actual hit could be a brief flash of concern and tension that passes after just a minute or two? You must know that it can also be a prolonged state of panic and anxiety that goes on for a few hours. So it is difficult to answer: how long do panic attacks last