House dust mite allergy is very common and may be the most common cause of year-round allergy and asthma.
Key points about dust mite allergy
- Many people with asthma, eczema and hay fever (allergic rhinitis) are allergic to a protein found in the microscopic waste of dust mites.
- It may be the most common cause of year-round allergy and asthma.
- Dust mite allergy can be diagnosed with a skin prick test which helps to find out what triggers your allergy.
- There are a few easy steps you can do to reduce house dust mites, such as hot washing bedding each week and keeping your home well-ventilated and dry.
- Antihistamines can also help manage the condition.
- If dust mite allergy continues to be a problem despite these measures, consider desensitisation therapy.
What are dust mites?
House dust mites are tiny bugs, too small to see without a microscope. They are present wherever people live. They thrive in warm, moist places such as mattresses, bedding and carpets, and feed mainly on flakes of dead skin, which humans constantly shed.
- Dust mites don't bite or pass on disease.
- They are only a problem to people who are allergic to their waste.
- A female dust mite can lay up to 300 eggs during its short 80-day lifespan.
- During its lifespan, a single dust mite can produce as much as 200 times its body weight in waste.
- Within the waste is a protein that is an allergen – a substance that starts an allergic reaction in many people.
What are the symptoms of dust mite allergy?
If you have an allergy to dust mites, you will have hay fever-like symptoms all year round, such as runny nose, sneezing, sinus congestion.
Signs that you might have an allergy to dust mites include:
- wheezing when you are vacuuming, dusting or spring cleaning
- allergy symptoms like runny or blocked nose or itchy eyes all year
- wheeze or cough when you enter a dusty room or house
- itchy nose, mouth, eyes, throat or skin
- puffy swollen eyelids
- asthma symptoms during the night or first thing in the morning.
What are the complications of dust mite allergy?
Dust mite allergy can cause you to get more sinus infections and make your asthma symptoms more difficult to control if you also have asthma.
Ongoing inflammation of tissues in the nose caused by dust mite allergy can block your sinuses, the hollow cavities connected to your nasal passages. These blockages may make you more likely to develop infections of the sinuses.
People with dust mite allergy and asthma often have difficulty managing asthma symptoms. Managing the dust mite allergy will often reduce the frequency and severity of asthma symptoms.
Other complications include:
- sleep disturbance
- fatigue and tiredness
- poor concentration
- poor memory
- missed days of work or school.
How is an allergy to dust mite diagnosed?
The symptoms of dust mite allergy can be similar to other conditions that might affect your nose, such as the common cold or nasal polyps. See your doctor to confirm whether your symptoms are due to dust mite allergy or some other condition.
Your doctor will ask you about your symptoms, and their relation to any common allergens. They will also examine your eyes, nose and throat for signs of irritation and congestion.
If you think you may be allergic to dust, or dust mite, ask your doctor for a skin prick test to help find out what is triggering your allergy. The skin prick test is done by applying drops of different allergens (such as dust mite extract) onto your forearm skin.
- These are numbered so the tester knows which is which.
- Then a tiny prick is made within each drop of extract.
- You then need to wait for 15 minutes – if you are allergic an itchy red bump (like an insect bite) will appear at the site.
How is an allergy to dust mite treated?
The best treatment for dust mite allergy is to avoid contact with the mite. Total avoidance of dust mite is impossible, but here are a few tips on how to reduce house dust mite population:
- Dust mites thrive in a moist environment. Keep household moisture levels low with a dehumidifier or ventilation system.
- Keep bedroom windows open where possible (in spring those with pollens allergies will want them closed).
- Treat any mould and the cause of the damp removed.
- Use extraction fans in bathrooms and in kitchens.
- Avoid drying washing indoors.
- Do not use humidifiers in bedrooms.
- Wash bedding (sheets, pillow slips, duvets covers) once a week, using a long and hot (60 degree Celcius) wash cycle.
- Do not eat on the bed or soft furnishings.
- Do not keep animals in bedrooms.
- Use dust mite covers on your bedding. These are a very efficient way of keeping the dust mite inside mattresses and stopping the food supply from entering into mite colonies. Plastic sheets are good only when they are brand new.
- Clean your bedroom twice a week with a damp cloth and mop. Avoid sweeping.
- De-clutter your bedroom – remove books, ornaments, silk plants and shelves from bedrooms.
- Carpets provide a great environment for dust mites. Remove wall-to-wall carpeting. Fixed carpets, especially those with thick underlay, harbour dust mites. Even the strongest vacuum cleaners cannot produce enough draft in the depth of the carpet piles to dislodge them. Rugs are the best way to go.
- If you can't live without a carpet, look for ones that are specially treated with an anti-microbial product.
- For vacuum cleaners to effectively remove dust mite particles, they must be fitted with a suitable filter (such as a HEPA filter), otherwise particles will just be spread throughout the room.
- Soft toys are an ideal environment for dust mite. A good way to reduce dust mite in soft toys is freeze the toys in the freezer and then place them in sunlight for 6 hours or put them in the dryer for half an hour.
- Remove or limit the number of stuffed toys in the bedroom.
- Boiling or heating materials to above 60ºC is efficient in killing the mites.
- The use of insecticide sprays is questionable and may be effective in reducing dust mite only for a short time.
Medicines for dust mite allergy
If you are unable to avoid dust mite waste (which is difficult to do in New Zealand homes where dust mites thrive), you may need to talk to your doctor about medicines to help control the allergic reactions. These are called antihistamines and come in different forms, including tablets, nasal sprays, eye drops and syrups.
Other medicines include:
- corticosteroid nasal sprays
- decongestants (for short-term use)
- medicated or non-medicated eye drops
- combination products that combine these medicines, eg, an antihistamine and a decongestant.
Ask your doctor or pharmacist about the best treatment option for you.
Allergen immunotherapy (AIT)
If other methods of managing dust mite allergy are not effective, desensitisation therapy may be considered. This treatment is also called allergen immunotherapy (AIT) or allergen vaccination and is done by a clinical immunologist.
It involves a series of injections of the allergen just below the skin surface. The injections start off with a very small amount of the allergen and the dose is gradually increased so that your body builds up immunity to the allergen. After the maximum dose is given, regular injections are given for 3 to 5 years to keep up the immunity.
What support is available with dust mite allergy?
Allergy New Zealand provides information, education and support for people with allergy, parents of children with allergy, teachers and healthcare professionals.
The following links provide further information about dust mites allergy. Be aware that websites from other countries may have information that differs from New Zealand recommendations.
Dust mite allergy Allergy New Zealand
House dust mite DermNet NZ
Allergen minimisation Australasian Society of Clinical Immunology and Allergy (ASCIA)
House dust mite and pet allergy Patient Info, UK
Treatment for dust mite allergy Mayo Clinic, US
- Specific allergen immunotherapy (AIT) environmental (inhaled) allergies The Paediatric Society of New Zealand & New Zealand Child & Youth Clinical Network, NZ, 2020
- Disease Summaries: Allergic Asthma: Symptoms and Treatment World Allergy Organisation