Will I have a problem joining if I used an inhaler one time after my doctor thought I had asthma, but ended up being seasonal allergies?

Depends on your age and whether or not you had a diagnosis of asthma. If you don’t have medical records on it, then I wouldn’t bring it up

Depends on the age at the time. The Army doesn’t care about anything that happened before you were 13 with regards to asthma. After that you will probably have a bunch of hoops to jump through if you aren’t excluded at all. I concur, ask your recruiter, but also remember that regardless of what he or she might advise you to say, your statements and denials are your own.

Ask your Recruiter, Charles.