My son has the flu. his pulse is 140 and rapid breathing. he has asthma so im a little concerned?

Concerned: You should be! Options: 1: Call your son's pediatrician. 2: Take your son to the Emergency facility if the pediatrician can't fit him in. All should go well but it might take a day or two.

Time to be seen: Sounds like he has developed some respiratory complications which can be serious in Flu.I almost lost a 3 yo last year to flu pneumonia, the first in 30+ years of practice but it does happen.Get moving.