House dust mite allergy
What is house dust mite allergy?
House mite allergy is a hypersensitive reaction to proteins in the excrement of dust mites. The many proteins attacks the respiratory passages causing hay fever and asthma. It will aggravate atopic dermatitis (eczema) in people who have this problem.
House dust mites are found in all UK homes. They are microscopic organisms that thrive in warm and humid houses with lots of food – human and animal skin and mould spores. The mites prefer to live in beds, which contain lots of moisture from our breath and bodies, plus the shed skin cells and, because we spend about a third of the day in bed, we inhale large quantities of dust mite allergens.
How do you become allergic to house dust mites?
The excretion of the mites contains a number of protein substances. When these are inhaled or touch the skin, the body produces antibodies. These antibodies cause the release of a chemical called histamine that leads to swelling and irritation of the upper respiratory passages - typical asthma and hay fever symptoms, and in the skin and eyes. The predisposition for allergy is often hereditary.
Unlike pollen, dust mites are present all year round causing constant allergy – 'perennial' allergic rhinitis. The excretion from the mites dries out and can be launched into the air when someone walks over a rug, sits down in a chair, moves on the mattress or shakes the bed clothes, giving allergic people immediate symptoms.
What are the symptoms of house dust mite allergy?
What makes the symptoms worse?
Air pollution such as tobacco smoke, chemical irritants or car fumes.
How does the doctor make the diagnosis?
It is often enough to tell the doctor when, where and how you get the symptoms. Skin tests and blood tests can be used for confirmation.
Good advice
It is best to do everything possible to avoid hypersensitivity to house dust mites. People who have perennial rhinitis, inflamed mucous membrane of the nose, or are allergic to house dust mites should try to adapt their homes.
What complications are possible?
Future prospects
If you are allergic to house dust mites, it is important that you don't expose yourself to the dust mite allergen because it increases your chances of developing asthma. The best remedy against house dust mites is described under the heading 'Good advice' above.
Your symptoms can be controlled by treatment, but you can't escape your hypersensitivity. If severe dust mite allergy is the only form of allergy you suffer from, your doctor may want to try immunotherapy – a 'vaccination' against the allergen.
This tolerance treatment involves regular allergen injections in increased doses over a period of three years, but is not routinely given and is not always successful.
There is also an oral immunotherapy treatment.
What medicine is given?
If the allergy causes asthmatic symptoms, some of the asthma medication below may be used
House mite allergy is a hypersensitive reaction to proteins in the excrement of dust mites. The many proteins attacks the respiratory passages causing hay fever and asthma. It will aggravate atopic dermatitis (eczema) in people who have this problem.
House dust mites are found in all UK homes. They are microscopic organisms that thrive in warm and humid houses with lots of food – human and animal skin and mould spores. The mites prefer to live in beds, which contain lots of moisture from our breath and bodies, plus the shed skin cells and, because we spend about a third of the day in bed, we inhale large quantities of dust mite allergens.
How do you become allergic to house dust mites?
The excretion of the mites contains a number of protein substances. When these are inhaled or touch the skin, the body produces antibodies. These antibodies cause the release of a chemical called histamine that leads to swelling and irritation of the upper respiratory passages - typical asthma and hay fever symptoms, and in the skin and eyes. The predisposition for allergy is often hereditary.
Unlike pollen, dust mites are present all year round causing constant allergy – 'perennial' allergic rhinitis. The excretion from the mites dries out and can be launched into the air when someone walks over a rug, sits down in a chair, moves on the mattress or shakes the bed clothes, giving allergic people immediate symptoms.
What are the symptoms of house dust mite allergy?
- Hay fever, runny nose, itching, sneezing.
- Watering itchy eyes.
- Asthma, coughing, difficulty in breathing.
- Eczema (inflammatory skin disease) may get worse.
What makes the symptoms worse?
Air pollution such as tobacco smoke, chemical irritants or car fumes.
How does the doctor make the diagnosis?
It is often enough to tell the doctor when, where and how you get the symptoms. Skin tests and blood tests can be used for confirmation.
Good advice
It is best to do everything possible to avoid hypersensitivity to house dust mites. People who have perennial rhinitis, inflamed mucous membrane of the nose, or are allergic to house dust mites should try to adapt their homes.
- Have as little upholstered furniture as possible in which mites can live.
- Clean walls, woodwork and floors with damp cloths. The floor can be polished.
- Only use rugs that can be washed once a week.
- Use cotton sheets, duvet covers and pillow cases that can be washed often at 60 degrees centigrade. Don't use woollen blankets or quilts.
- Totally encase your duvet, all pillow cases and mattress with special barrier covers that have been tested to prevent the fine dust of the house mite excrement from escaping or allowing it to enter (see Allergy UK Seal of Approval products). Cheaper covers widely available usually do not work. If you cannot buy these, then use synthetic duvets or covers that can also be washed at 60°C.
- Put duvets and pillows in plastic bags and put them in the freezer for 24 hours at least once a month as an alternative to proper barrier covers.
- Make sure your chairs are made of wood or plastic.
- If you can, use roller blinds and dust them daily.
- Use microfibre damp cloths and a vacuum cleaner with a no bag vortex and allergen filter to clean the house thoroughly, preferably every day, but at least twice a week.
- Avoid dust traps like teddy bears, cushions, dried flowers, bric-a-brac and toys.
- Choose a cuddly toy that can be washed regular at 60°C (in a pillow case) or can be put in the freezer for 8 hours every month.
- Wash bedding etc at a temperature of at least 60°C to kill the house dust mites.
- Leave bedding, duvets, pillows and mattress exposed to sunlight/daylight for at least an hour every day (hang duvet over chair or banisters).
- Dust mites hate dry and cold air, so try to air the house every day and don't use an air humidifier, which will only make matters worse. If the lower edge of the window is moist when you wake up in the morning, there is too much humidity in the air.
- Do not spray the house, it may worsen your symptoms.
- Do not touch dusty objects like books and old clothes.
- When you are likely to be exposed to substances that give you a reaction, eg when you are house cleaning, you should wear a mask.
- Keep household chemicals to a minimum.
- Don't allow smoking in the house.
What complications are possible?
- You are predisposed to other respiratory diseases.
- You are also predisposed to otitis, inflammation of the ear.
- Chronic eczema symptoms.
- You may have trouble sleeping and suffer from chronic fatigue.
- Hospitalisation following a severe asthma attack.
Future prospects
If you are allergic to house dust mites, it is important that you don't expose yourself to the dust mite allergen because it increases your chances of developing asthma. The best remedy against house dust mites is described under the heading 'Good advice' above.
Your symptoms can be controlled by treatment, but you can't escape your hypersensitivity. If severe dust mite allergy is the only form of allergy you suffer from, your doctor may want to try immunotherapy – a 'vaccination' against the allergen.
This tolerance treatment involves regular allergen injections in increased doses over a period of three years, but is not routinely given and is not always successful.
There is also an oral immunotherapy treatment.
What medicine is given?
- Medicines for allergies include:
- Antihistamine tablets or syrup (eg loratadine, cetirizine). These lessen the allergic reaction by blocking the actions of histamine. They relieve hayfever symptoms.
- Nasal sprays or drops containing sodium cromoglicate, corticosteroids (eg beclometasone) or antihistamines (eg levocabastine). These can be used to reduce nasal inflammation and control symptoms in the nose.
- Eye drops containing sodium cromoglicate, nedocromil, or antihistamines (eg azelastine) reduce eye inflammation and can be used if eye symptoms are a particular problem.
If the allergy causes asthmatic symptoms, some of the asthma medication below may be used
- Relievers (bronchodilators): these are quick-acting medicines that relax the muscles of the airways. They are used when required to relieve shortness of breath. If used regularly more than three times weekly, a preventer is needed.
- Preventers: these act over a longer time and work by reducing the inflammation within the airways. They should be used regularly for maximum benefit. When the dosage and type of preventive medicine is correct, there will be little need for reliever medicines.