Jane, there may be another cause for the symptoms, what about dust mites in the bed linen, which are microscopic, and cause itching, leading to scratching and infection? I have seen an expose' of the portable air purifiers used to get rid of dustmites and other airborne pests. They said the units cannot solve the dustmite problem on the bed linen, because the mites cling tightly to the cloth, and do not fly around the room, so they do not get filtered by ANY of the purifiers. I would advise to wash the bed linen with HOT water in a washing machine, and do it often. See if this helps the rashes. I had chronic hives for a long time, and I symapthize. KenBecker @/AOL.COM