Allergies are a fluke of the immune system in which substances called allergens trigger bodily reactions as though the allergens were harmful invaders, despite them being benign. When triggered by an allergen, the immune system releases immunoglobulin E, which tells mast cells and basophils to ward off the substance using histamines and other chemicals. For about 15 percent of the population, the proteins in pet saliva, pet dander and fur can act as allergens. Symptoms can include itchy eyes, runny nose, rash, difficulty breathing, congestion and sneezing.

Since giving up your pet isn't always a pleasant solution to the problem, many people try to keep their pets at home, despite their allergies. There are ways to combat the allergies - mainly, by reducing exposure to the allergens. For instance, people with pet allergies shouldn't let their pets into the bedroom, since people tend to spend a large proportion of their time in the bedroom. Good air filters can help reduce allergic reactions, as does regular house cleaning and frequent hand washing. Also, bathing your pets weekly and brushing them daily helps reduce the allergens floating around the house. Allergic pet owners should encourage their pets to spend more time outdoors. In some cases, doctors will offer allergy shots, also called immunotherapy, to help your body adjust to pet allergens.

In other cases, however, you're best off finding a new home for your pet. After your pet has been placed, your allergic symptoms might not disappear right away. While your symptoms should subside within a few days or weeks, if your allergy is to dander or fur and any of it is left in the house (which it probably is), it'll take until the house is free of allergens for all your allergy symptoms to go away. This takes an average of 20 weeks, but could even take a year.