According to my Chinese acupuncturist, acupuncture works by causing release of endorphins. That won't do anything for allergies.
After 4 or 5 sessions the allergen may be gone from the environment.
I tried it for pain with absolutely no relief, and it seemed the pain got worse. It's expensive and not covered by insurance. For me, the needles hurt - a lot! Personally, I wouldn't do it to a kid.
But maybe it works for some people.