It's very real. My daughter, who is 4, has been to the ER three times after being exposed to whatever it is in peanuts that causes the reaction. She's not a pretty sight when it happens.
My wife and I take it in stride. We make sure she takes the responsibility for what she puts in her mouth instead of making the world conform to her. (I don't trust the world to watch out for my kid.) It's worked well for us. She does a firm but friendly interrogation of food contents.
I'm certainly sorry to hear about the challenges that your daughter has to face, but I'm convinced that you're taking the right precautions in the face of this.