>>12301779Allergies and immunity go hand in hand. One day your body might decide birch pollen is a danger and treat it like anyone else's body would react to a severe infection. Then one day you're not immune to it any more and your body forgets about it as a threat completely. My cousin had/has a birch allergy when she turned like 20 and apparently you really can't eat anything. I'm immune to poison ivy because my body doesn't recognize it as a threat, but it could be the next time I walk through it that I break out in a rash, same with birch pollen.
