People with allergies, especially to dust mites, need to do a few extra things around the house to limit their exposure.
Keep the bedroom clean and clutter free. Things like extra pillows, drapes and stuffer furniture hold household dust which has dust mite feces in it.
Wash the bedding in hot water or with special laundry additives.
Get rid of the carpets if possible
Keep the pets out
The other thing you can do is talk to your friends and see what they are doing. None of us have all the answers and just because something worked for one person does not mean it will work for another.
Here is another article forwarded to me that has additional information and tips for dealing with allergies. Some it I agree with and some I don’t. Read Article “5 Secrets To Eliminate Allergy And Asthma Symptoms Caused By Dust Mites“