Can any doc tell me what's the best way to deal with mold allergies in an old house?

Mold Allergy: If there is visible mold on walls have it removed and replaced with clean drywall. Attempt to have any damp/wet places in the house fixed so that mold doesn't have a place to set up shop, especially in basement areas. If you have daily symptoms of congestion try OTC steroid nasal sprays and/or saline rinses. See allergist if no improvement, consider allergy shots if persistent.