Good question Akroeze!
Assuming her lwr airways are not involved, and there is no stridor...
Lemme throw this by you...
The pt is obviously having an allergic reaction. At this point the swelling (although slow) is becoming an airway problem. We need to do what we can to reduce the swelling and manage the airway.
The pt got 50mg PO of benadryl, remember all drugs thet go enteral are subject to first pass metabolism. The dose was also 3hrs ago. so really, as far as bloodserum levels are concerned, she is not "maxed out" as far as therapeutic index goes. In fact, she is probably below.
I would give 50IV myself.
That aside though
I tend to agree with the IM Epi being a little risky with this pt who at this point.... is pretty stable.
I would have no problem trialing a local epi via nebulizer to vasoconstrict and somewhat make her more comfortable.
Also, getting a little epi into the system is always a good thing during allergic reactions with airway comprimise as it does in fact stabilize the MAST cell, therefore inhibiting the release of more histamine.
I also may hit her with a Dexamethosone, or prednisone. It will help with the swelling somewhat, but moreso, we will be one step ahead in case this does go for shit later.