I prewash fabric due to allergies - mine! When a quilt is completed, I wash it in cold water, and a free and clear detergent, color catchers. Then it goes into the dryer on the hot setting. I don't use fabric softener or fabric softener sheets because of my allergies.
So far, all have survived the wash in good shape. I generally quilt moderately densely, so there is never an unquilted space larger than 4 ".