Allergy to House Dust Mite and Pets

Two common allergies

Allergy to house dust mite
The house dust mite is a tiny creature that lives in every home. It mainly lives in bedrooms and mattresses where it lives off human skin scales and forms part of the dust. It usually causes no harm, but some people are allergic to the tiny droppings (faeces) of the mite. A 'skin prick' test can confirm the allergy.

Allergy to pets
Cats are the most common culprits, but allergy to other animals such as dogs, horses, hamsters, etc, can also occur. Dander or hairs from a cat or other animal can remain airborne for hours, and then settle onto soft furnishing, floors, and carpets. Therefore, even when the animal is not close, you can still be in contact with the cause of the symptoms. A 'skin prick' test can confirm the allergy.

How do symptoms develop
Symptoms of allergy are due to the immune system reacting to an allergen (such as mite droppings or dander from a pet). Cells in the lining of the nose and eye release histamine and other chemicals when they come into contact with the allergen. This can cause:

• inflammation in the nose (rhinitis). Symptoms include sneezing, a blocked or congested nose, a watery discharge ('runny nose'), and an itchy nose.
• inflammation of the front of the eye (conjunctivitis). Symptoms include red, watering and itchy eyes.

If you already have asthma, the allergy can sometimes make the symptoms of asthma worse.

What are the treatment options?

Treatment with medication
Treatment with nose sprays, eye drops and/or antihistamine tablets will often ease or clear the symptoms. The treatment is the same as for any cause of allergic rhinitis or allergic conjunctivitis. See separate leaflets called 'Persistent Rhinitis' and 'Allergic Conjunctivitis' for details.

Avoiding the cause of the allergy
Treatment with medication often works so well that you may not have much motivation or need to avoid the cause of the allergy. However, some people may wish to try to avoid the cause of the allergy, particularly if medication is not fully effective. For example, some people decide to give up a pet if it is the cause of the symptoms.

If house dust mite is the cause of the allergy, it is impossible to keep your home permanently clear of the mite. However, the following will help to greatly reduce their number, which may ease symptoms. The main focus is on the bedroom.

• Remove carpets (where possible) from the bedroom. Avoid soft furnishing in the bedroom.
• Use dust tight ('mite proof') covers for mattress, duvet, and pillow. This can be left in place for several months. The usual covers can be put on top of the special covers, but should be washed every 1-2 weeks at 60 degrees centigrade.
• Use feather rather than synthetic pillows (this is the opposite to what used to be thought).
• Wet-dust the bedroom furniture every 1-2 weeks.
• Vacuum or clean the bedroom floor regularly. Use a vacuum cleaner with a good filter (this removes the mite and prevents small particles coming out through the vacuum exhaust).
• Regularly ventilate the bedroom (open the door and a window for a while on most days).
• Keep soft toys to a minimum. Put them in the freezer in a plastic bag for 24 hours now and again. This kills any mites on them. If the toys are washable, wash them at 60 degrees centigrade after putting them in the freezer.
• Try to keep humidity low (for example, do not dry washing on the radiator).
• Let bedding air after use (that is, fold back duvet or blankets to allow sheets to air).

Immunotherapy (desensitisation)
This treatment is sometimes used, mainly in cases that are severe and where symptoms are not helped much by other treatments. It is done using a series of injections to 'desensitise' the immune system. Another technique is being developed which involves placing the allergen under the tongue.

Further help and advice

Allergy UK   No 3 White Oak Square, London Road,, Swanley, Kent, BR8 7AG
Tel: 01322 619898    Allergy Help Line: 01322 619864    Web: www.allergyuk.org

© EMIS and PIP 2005   Updated: May 2005   CHIQ Accredited   PRODIGY Validated

The authors and editors of this article are employed to create accurate and up to date content reflecting reliable research evidence, guidance and best clinical practice. They are free from any commercial conflicts of interest.

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