There is no known way to prevent development of allergies, but recent research has given us clues.

Breastfeeding can be effective at preventing and decreasing allergies. There is also evidence that exposures to certain allergens in the first year of life may prevent some allergies. This is called the "hygiene hypothesis" and sprang from observations that infants on farms tend to have fewer allergies than those in environments that are more sterile. Once allergies have developed, avoiding known allergens may decrease symptoms and prevent other allergies.

Mold spores are everywhere. Minimize exposure by keeping rooms dry, using a dehumidifier if neccessary. Discard moldy or mildewed articles (books, toys, shoes, and so on). Use synthetic fabrics for clothing and household furnishings whenever possible. Disinfect bathrooms, basement walls, and furniture with diluted bleach or other appropriate disinfectant solution.

Clean frequently to minimize dust. Vacuum frequently, preferably using a small-pore filter to capture dust mites. Damp-mop and dust often. Eliminate as many "dust catchers" as possible, including rugs, bed ruffles, or canopies, and curtains. Bedding and mattresses harbor dust mites. You can buy special covers for mattresses, box springs, and pillows to reduce dust mite allergens. Wash rugs, bedding, and furniture coverings weekly if possible. Central heating and air-conditioning systems may be helpful, particularly if they include special filters to capture dust.

People who are allergic to animals may need to avoid keeping pets. Frequent bathing and grooming of the pet (preferably by someone who is not allergic to the animal) may help. Allergy to animals may also include wool, which may contain tiny amounts of dander (skin).

Avoid other irritants whenever possible.