Why does our immune system sometime overact to harmless allergens? instead of using suppressants, can we tell our body to ignore specific allergens?

Immune system: If only we knew. There is a certain evolutionary advantage to forming antibodies against substances that can harm you, but clearly the body at times goes overboard and generates such an intense allergic response (anaphylaxis) that it can kill us, or it builds up chronic allergic symptoms to foods, pollen, pet dander, etc that appear to have little adaptive advantage.