Allergies are a result of your immune system misidentifying certain substances. Instead of registering allergens as the harmless materials they are, your body thinks they're dangerous invaders and sets out to neutralize them by releasing chemicals to attack them. That's why you end up with congestion, coughing, sneezing and sometimes worse. When people are allergic to dogs, the allergy is usually to the animal's dander, or shed skin flakes. Dander is like dandruff, but much smaller. It hovers in the air and when you breathe it in, your allergies act up. Occasionally, dog allergies are reactions to saliva or hair.
Most home remedies for dog allergies are preventive in nature. The first step is to eliminate items from the house that serve as collection spots for dander. That means getting rid of carpets; replacing them with throw rugs allows you to launder your floor coverings. When you dust the house, use a wet cloth so that you absorb the dander and other allergens instead of just tossing them up into the air. And using a high-quality air filter helps reduce the allergens floating around, too. If you must vacuum or do other cleaning, wear a mask to prevent yourself from inhaling dander. But it's even more effective to hire someone else to do your cleaning. In either case, a specialized HEPA vacuum cleaner will probably be the most effective.
Another trick to reducing allergens in the house is to limit the places your dogs is allowed to go. It's especially important to keep your pet out of the bedroom. Some people suggest that you leave one room as a complete sanctuary from pet dander by keeping the dog out and using air conditioning instead of letting allergen-filled air circulate in and out.