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Prevention: There is some evidence that children who were breast-fed have fewer type I and type IV hypersensitivities. It is also thought that too restricted and hygienic an environment may play a role in increasing allergies. Some studies have shown that infants raised on farms tend to have fewer allergies than those raised in a more allergen-free environment.

Avoidance and elimination: Once an allergy has developed, the best way to prevent a reaction is to prevent exposure wherever possible. In the case of food, this may mean a lifetime elimination of that substance from the diet and vigilance in watching for hidden ingredients in processed and restaurant food. For example, a spatula that has touched peanut butter cookies before touching chocolate chip cookies may be contaminated enough to provoke a reaction in a peanut-sensitive person.

In the case of insects and animals, avoidance is best. In the case of airborne pollens, such as regional weeds and grasses, limiting time outside can help but may not prevent the problem. Some people try moving to another area to avoid certain local allergens; this may not be effective since people with allergies often develop new allergies to pollens or grasses in the region they move to.

Desensitisation: Immunotherapy is sometimes recommended if the allergen cannot be avoided. It includes regular injections of the allergen, given in increasing doses that may acclimatise the body to the allergen. The injections decrease the amount of IgE antibodies in the blood and cause the body to make a protective antibody known as IgG. Because it moves across the placental barrier, IgG is important in producing immunity in an infant before birth. Immunotherapy injections can cause side effects, like a rash and can trigger anaphylaxis. Desensitisation is most effective for those with hay fever symptoms and severe insect sting allergies. Many with hay fever may have a significant reduction in their symptoms within 6-12 months and it is effective in about two-thirds of those who try it. They may continue their injections for three years, then consider stopping. Some will have long-term relief; others will see their symptoms come back. Immunotherapy is not recommended for food allergens except in clinical trials at present.

Short-term treatment is used for the relief of symptoms. For example, with respiratory symptoms it may include antihistamines, topical nasal steroids, and decongestants.

In the case of anaphylaxis, adrenaline injections are required. Those who have severe reactions must carry adrenaline with them at all times. Anyone who has a reaction and uses adrenaline should seek medical treatment, as follow-up treatment is often needed.

Last Review Date: February 13, 2019