The optimal treatment for severe house dust mite allergy
is long acting antihistamines like Allegra 180mg once daily plus flixonase or nasonex nasal spray
1-2 sprays/nostril twice daily. Montelukast 10mg can be added at night if there is asthma or lung hyperresponsiveness.
Montair LC is a combination of montelukast and Levocetirizine
that can be given in severe dust allergy
. Montelukast has side effects though nothing very serious and the only serious one reported in develpment of Churg Strauss syndrome, a vasculitis, though yet to be proven. Levocetirizine is a very safe second generation antihistamine.
The long term treatment is immunotherapy
(subcutaneous or sublingual drops) against house dust mite given over 3-5 years. This should only be given by a specialist trained in this therapy.
I hope this helps.