HI, Thanks for your question. My name isXXXXX and I am here to help you today. I will be happy to help you with your follow-up questions also. I am going to address your primary concern first. Yes the asthma attack that comes all of a sudden with a severe intensity is more dangerous as compared to one that develops gradually over a period of time. There are many reasons like the one which comes suddenly is usually a severe one and one might not be in a position to get the inhaler or the other medicines. However as a general rule, you should use your inhaler immediately as soon as you feel that you are getting an attack. You should not wait for this attack to progress to a certain extent. I hope i have answered your question but please ask if you have any question because our discussion always remains open so you can always ask more till you are satisfied, You can click the smiley to rate the answer. You can come back here to ask anything even after you have rated the answer. I will be glad to help you always.