[cyberax]

> You can become allergic to new things, but you won't lose allergies unless the recognizer population dies off entirely.

That's not true. Desensitization therapy often works.

The trick is to introduce the allergens into the bloodstream, bypassing the skin.

[kelnos]

I don't think that's necessary. I've been doing allergy immunotherapy for the past few years, and it's all subcutaneous. Definitely not into the bloodstream.