Back pain. Headaches. Allergies. Arthritis. Anxiety. Morning sickness. Acupuncture practitioners claim their centuries-old approach can successfully treat dozens of medical problems—with few side effects or risk of complications.

But is acupuncture legit? And how can having someone prod your bod with skinny needles relieve aches, pains, or hay fever from hell? Here’s a roundup of what we do and don’t know about acupuncture, so you can decide if it’s right for you, as well as how to pinpoint the best practices.