When you have real severe allergies extra efforts must be made to control the indoor air enviroment where you live. You need to make sure that the rooms are as free of allergens as they can be. There are a number air purifiers available to do the job. Special work needs to be done in the bedroom where you spend about 1/3 of the time (based on eight hours of sleep).
More details on this are available in the National Institutes of Health allergy report that is available at: