Hibiclens - is this good to use when you have dustmites rashe?

Hibiclens contains chlorhexidine which is an antiseptic. It works by destroying germs on the skin.
Hibiclens is used to clean the skin before surgery to reduce the risk of infection. It may also be used to treat acne.
see http://www.drugs.com/mtm/hibiclens.html

A rash that is caused by dust mites is allergy related and would be best treated with antihistamines or topical corticosteroids. Your pharmacist can advise on the most suitable product for the treatment of your condition.