Dust mites eat skin cells people shed, and rather than drinking water, they absorb water from humidity in the atmosphere. They thrive in temperatures around 70 F (21 C) and a relative humidity around 70 percent.
Household dust contains all kinds of tiny particles, but a large portion of it is made up of human skin cells. This dust is easily trapped in the fibers of bed linens, furniture cushions and carpeting. These materials also hold moisture well. Consequently, bedrooms are ideal habitats for dust mites. Dust also contains the feces and decaying bodies of dust mites, and it's a protein present in this dust mite "debris" that's the culprit in dust mite allergy. What causes the allergic reaction?
Dust mite allergy is an immune system reaction to a certain dust mite protein. This reaction triggers inflammation in the lining of the nasal passages (allergic rhinitis), causing sneezing, runny nose and other signs and symptoms associated with hay fever.
If you have dust mite allergy, your body generates an allergy-causing antibody to a protein found in the dust mite debris. In other words, it's mistakenly identified this protein as something that could harm you. Once your body has developed an allergy-causing antibody to a particular agent (allergen) — in this case, the dust mite protein — your immune system will be sensitive to it. When you inhale dust mite debris, your immune system responds and produces an inflammatory response in your nasal passages or lungs.
The dust mite allergen can cause two kinds of immune system responses in the airways of your lungs. An allergen can prompt inflammation in air passages. Therefore, prolonged or regular exposure to the allergen can cause the ongoing (chronic) inflammation associated with asthma. Exposure to an allergen also may cause sudden, severe constriction of air passages (bronchospasms).
For some people, dust mite allergy may be the primary cause of inflammation and contraction of airways of the lungs (asthma), resulting in wheezing, shortness of breath and other breathing difficulties.
Dust mites, relatives of the spider, are too small to see without a microscope. Dust mites eat skin cells shed by people, and they thrive in warm, humid environments. In most homes, bedding, upholstered furniture and carpeting provide an ideal environment for dust mites.
Steps to reduce the number of dust mites in your home can often control dust mite allergy. Medications or other treatments may be necessary to relieve symptoms and manage asthma.
Dust mite allergy symptoms caused by inflammation of nasal passages include:
- Runny nose
- Itchy, red or watery eyes
- Nasal congestion
- Itchy nose, roof of mouth or throat
- Postnasal drip
- Facial pressure and pain
- Frequent awakening
- Swollen, blue-colored skin under your eyes
- In a child, frequent upward rubbing of the nose
If your dust mite allergy contributes to asthma, you may also experience:
- Difficulty breathing
- Chest tightness or pain
- An audible whistling or wheezing sound when exhaling
- Trouble sleeping caused by shortness of breath, coughing or wheezing
- Bouts of coughing or wheezing that are worsened by a respiratory virus such as a cold or the flu
A dust mite allergy can range from mild to severe. A mild case of dust mite allergy may cause an occasional runny nose, watery eyes and sneezing. In severe cases, the condition is ongoing, or chronic, resulting in persistent sneezing, cough, congestion, facial pressure or severe asthma attack.