Have you tried a different kind of fiber? Different fibers have to be dyed with different chemistry If you've been using man-made fibers, try natural fibers. Try fibers dyed with plant dyes.

Maybe there is sizing in the yarn. Try washing it before using it.

What kind of reaction are you having? Skin rashes, runny nose?

Eileen

I have allergic asthma. My hands itch and swell, I become congested, and then, cannot breathe well. I did wash crochet string and wind it around a Christmas light holder to dry. I haven't tried crochetting with it, yet.