i buy dust mite proof bedding cover (suggest by a paediatric dermatologist) , and my baby have no 濕疹. He said if i let him have 濕疹 and don't control the environment, my baby will have 哮喘 after 5 years old.
basically, dust mite cause 鼻敏感, 濕疹 n 哮喘. ( my understanding)