Allergies > Avoiding allergens
Allergen avoidance is active avoidance of the allergen that causes your allergy. This is usually recommended for all people with allergic rhinitis.
The simplest treatment for allergic rhinitis is to avoid the allergen that causes your disease. This should be tried before taking medication, and may reduce symptoms to a level where they are no longer troublesome.
It may require some effort to avoid a particular allergen, so it is essential that you find out exactly which allergens cause your disease. A technique known as skin-prick testing can quickly and easily show which allergens you are sensitive to. If you have not had this done, your doctor should be able to arrange it.
Skin prick tests will identify the allergen that causes your allergic rhinitis.
A drop of solution containing each suspected allergen is placed on your skin (usually on the arm) and the skin is pricked through the drop.
If you are allergic to the allergen, your body will produce an immune reaction against it. This results in the production of a chemical called histamine, which causes the skin around the prick to become inflamed (it becomes red and swollen, but this does not last very long). Your skin will not change if you are not allergic to the allergen.
To check that the test is working, you will also be given the test using a drop of histamine and one of saline. These are positive and negative controls respectively, as your skin should react to the histamine drop, but not the saline drop.
You will be asked to not take antihistamines for a couple of days before having the skin prick test.
The following sections recommend methods of avoiding particular allergens. Some of these require more effort to do than others. The actions you decide to take will depend on the severity of your symptoms and how strongly you want to avoid using drugs to treat your allergy.
House Dust Mite Allergens
House dust mites are found in all homes, and can cause perennial allergic rhinitis. They live in warm, humid places such as mattresses, bedding, rugs, clothing, and upholstered furniture. House dust mite allergens are found on house dust mite body fragments and faeces.
To reduce contact with house dust mite allergens, several actions can be taken. Some of these are more drastic than others, and whether you want to do them will depend on the severity of your disease and whether you want to avoid using drugs.
- Wash bedding weekly at 60°C
- Damp-clean furniture in bedrooms
- Remove stuffed toys from beds
- Vacuum clean weekly: ask a non-allergic person in the household to do this; if this is not possible, wear a mask whilst vacuuming and leave the room for 20 min afterwards
- Encase bedding, box springs, and mattresses in fine weave, plastic, or vapour-permeable covering
- Reduce indoor humidity eg by improving ventilation or using a dehumidifier
- Use pesticides (acarides) that kill house dust mites (this has not been proven to work)
- Replace carpets with hard wood flooring
- Replace curtains with blinds
- Replace upholstered furniture with leather, vinyl, or wooden furniture
- Avoid living in basements
Animal AllergensPeople may be exposed to animal allergens at home (pets) or at work (eg cattle for farmers, laboratory animals for scientists). Continuous exposure may cause perennial allergic rhinitis. Animal allergens are found on fur, feathers, and animal bedding.
Sadly, the best way to avoid pet allergens is to find your pet a new home. This is obviously easier said than done. Drug treatment may help some people to live with their pets, but this may not be effective for people with particularly severe allergies. Before any decisions are taken, it is important to confirm by skin-prick testing that the animal in question is really to blame for the allergy.
If you decide to keep your pet, the following actions should help to reduce your allergy to it:
- house the pet outside, or restrict it to one area, preferably one with a hard floor
- if possible, wash the pet weekly
- use high-efficiency air cleaners
- replace carpets with hard flooring
Pollen contains the male sex cells of plants, which are used to fertilise the female sex cells (eggs). Many plants have pollen that travel to the female parts of other plants in the wind. Airborne pollen may cause allergies when inhaled.
Grass, weed, and tree pollen can cause seasonal allergic rhinitis (hay fever) in areas where plants have seasonal pollen production, and perennial allergic rhinitis in areas where plants have continuous pollen production.
The amount of pollen in the air usually varies depending on the season, weather, location etc. Weather forecasts often provide pollen counts, which are a measure of the amount of pollen in the air.
People who suffer from pollen allergies (hay fever) only have to worry about avoiding pollen at times of the year when pollen counts are high (mainly spring for tree pollen and summer for grass pollen).
Unfortunately, pollen avoidance is difficult because it is so widespread, but there are some sensible measures that can be taken:
- keep house and car windows shut during the day in the pollen season
- restrict outdoor activities to later in the day, when pollen counts are lower
- avoid the countryside, and even stay inside when pollen counts are high
- use air conditioning
- if possible, take summer holidays by the coast, where pollen counts are lower
Indoor Mould Allergens
Mold (Fungi) Spores
A spore is the reproductive body of a mould (fungus). When inhaled, mould spores (found outdoors and in the home) can cause allergic rhinitis.
The spores may cause seasonal allergic rhinitis in areas where moulds are more common at certain times of the year, and perennial allergic rhinitis in areas with constant mould spore production.
You can limit indoor mould growth by maintaining relative humidity at 50% or less using an exhaust fan or dehumidifier. In addition, bleach can be used to kill mould.
People with allergies should also try to avoid general irritants such as cigarette smoke.
Skoner DP. Allergic rhinitis: definition, epidemiology, pathophysiology, detection, and diagnosis. J Allergy Clin Immunol 2001;108:S2–S8.
Patel NK, Bush RK. Role of environmental allergens in rhinitis. Immunol Allergy Clin North Am 2000;20:323–353.
Eggleston PA, Bush RK. Environmental allergen avoidance: an overview. J Allergy Clin Immunol 2001;107:S403–S405.