I'm an asthmatic and had to run to the ER myself for sex induced attacks. It may help you to know that asthma is an inflammatory disease. What is more flaming than sex?
Chances are, unless a cure for asthma develops, this will always be a part of her sex life. It is her health, it is her responsibility to learn how to handle it, and it is her responsibility to communicate with her partner so she doesn't scare the daylights out of him. (Past mistakes I have made, not warning the BF!)
Don't let this scare you into avoiding sex or orgasm, just be prepared. If she's prone to allergies, she should avoid anything made with latex, don't use anything with fragrance, (no cologne, aftershave, perfume, scented candles etc. These may be triggers.) I have been turned off to sex by a BF's cologne because I couldn't go near him without wheezing. If you bring her flowers, make sure she's not allergic to them. Talk to the doctor about adjusting your meds and what to do. Sex is exercise, most asthmatics need to take a breathing treatment 20 minutes before "exercising". (From what I gather in the post, she is trying to treat it during the activity instead of before it.) Ask the doctor about keeping an epipen handy for severe emergencies, (not just from sex).
I have been living with this for 5 years. Even with doing everything I'm suppose to do and using my medication properly, I still have attacks sometimes during sex. It happens. Have a plan of action, make sure your inhaler and other emergency meds are within reach. Last thing you want is your rescue inhaler strewn across the room underneath the clothes somewhere, rolled under the bed, or downstairs in your purse.
sixxfan68