DS2 was diagnosed with dust mite allergy and asthma earlier this year after having a severe asthma attack triggered by being around a dog. We had him allergy tested as, while we knew he was allergic to dogs, we wondered if there was anything else which would compound the reaction as he’d never been that bad before. That revealed a dust mite allergy and explained why his dog allergy is much worse, he’s already reacting to something else.
I hate to say it but it’s a really shit allergy to have. It’s expensive to make the changes needed such as removing carpets, boxing up toys, buying mattress/pillow/duvet encasements, HEPA air purifier and HEPA filtered hoover, etc. Then the relentless cleaning. Your DS might not need all these things depending on his severity.
Essentially, there is no single thing that helps but a combination of lots of little things. Most exposure will be in his bedroom from his bed and carpet. Encasing the mattress and pillow in allergy covers, removing the carpet (or at least hoover regularly for now) and damp dusting his bedroom regularly would be the things to prioritise.
Firstly tackle the bed. Mattress encasements like allerguard and astex are expensive (though dust mite allergy/asthma sufferers can get them VAT free). We haven’t got those yet but have found Silent Night allergy mattress protector, allergy pillow protector and an anti allergy duvet have worked well so far. We wash his bedding weekly at 60C and tumble dry it.
DS2 is 13 so was quite happy to just get rid of his remaining cuddly toys. But for a younger child, teddies can also go in the freezer for 24hours. This kills the mites but doesn’t remove the allergens already there so best to wash also. Unfortunately, to make this easier reducing the number he has (or at least the ones out on his bed at any one time) would be best.
Lego, again, he’s going to have to put away when done. Plastic boxes to help sort current builds, can get plastic display boxes for any he wants to keep built.
DAMP dust regularly. I bought microfibre cloths which I dampen and a reminder set on my phone so I’m dusting around the house every day (his room I do about 2-3 times a week). Don’t dry dust because it doesn’t catch it all and makes some airborne.
Try not to dry washing in the house and use a dehumidifier (even when not drying washing this is a good idea). If you don’t have one, can’t afford one, opening windows regularly helps to reduce the humidity in the house too. Dust mites get their water by absorbing moisture from the air; less moisture means fewer mites and less allergen.
Allergy U.K. are currently running a campaign on respiratory allergy awareness including dust/mold and pet allergies in the home. They have lots of information on their website that might be helpful https://www.allergyuk.org/wellcome-home/