Allergies: What can you do around the house to reduce allergy symptoms caused by house dust mites?
More than average cleaning and removing “dust traps” in bedrooms might help reduce the symptoms of house dust mite allergy. However, dust-mite-proof bedding and air filters have not been proven to help.
People with year-round hay fever (called allergic rhinitis) are often over-sensitive to particular particles in the air. These so-called allergens include plant pollens, animal hairs, skin particles, and house dust mites. House dust mites are tiny arachnids that are everywhere that people live, work or go to school. This is because they live on the tiny flakes of skin that people and animals are constantly shedding.
Microscopic bits of house dust mite droppings and pieces of dead dust mites are in the air, mattresses, bedding, pillows, carpets, curtains and stuffed toys. These allergens get into the airways and are a common cause of allergies and allergic asthma. House dust mites are everywhere: they are not a sign of poor hygiene.
People who are affected by allergic rhinitis tend to sneeze a lot, their nose runs or is blocked, and their eyes itch and tear up. If allergic rhinitis affects the eyes too, it then called rhinoconjunctivitis. There are tablets, eye drops and nasal sprays for treating these symptoms. Antihistamines and medicines containing corticosteroids are often used. Specific immunotherapy can also reduce some of these allergies. This involves repeated injections over the course of several years of very small amounts of the substance that is causing the allergic reaction. For some allergies, there is also a version of immunotherapy called “sublingual immunotherapy”. That involves repeatedly dissolving small tablets or taking drops containing allergen solutions under the tongue over a long period of time. The goal is to reduce sensitivity to the allergen.
Allergy against house dust mites causes year-round symptoms
People who are allergic to particular pollens will have symptoms mostly in spring and/or summer. During this time they really cannot totally avoid these allergens in the air. It is different for people who are allergic to house dust mites. Although they can be bothered by symptoms all year long, they might be able to reduce the amount of allergen that they are exposed to. The most likely place where it might be possible to make a difference is at home.
There is no shortage of recommendations about what to do around the house or apartment to reduce house dust mites. People are often told to air the home regularly, wash bedding often and clean the floors a lot, too. Another common suggestion is to get rid of “dust traps” like fabric-covered furniture, carpets and curtains.
There are also machines for filtering the air. Air filters fitted with HEPA (“high efficiency particulate air”) filters are supposed to help reduce the amount of house dust mite allergen in the air. There are also special mattress covers or protectors that are supposed to be dust-mite-proof and special anti-dust-mite sprays for the mattress, bedding and other surfaces. Some of these sprays are plant-based, but most are based on chemicals that kill dust mites (pesticides called acaricides).
Testing whether or not these measures work in the bedroom
Researchers from the University of Edinburgh working for the Cochrane Collaboration wanted to see if research has proven whether or not household changes can reduce symptoms from allergic rhinitis. The Cochrane Collaboration is an international research network that investigates the benefits and harms of different treatments. The researchers were interested in whether people had less time off work, whether their quality of life improved, if they used less allergy medication and if the different measures caused adverse effects.
The researchers only analyzed the results of randomized controlled trials, because this kind of research provides the most reliable answers about the effects of treatments and other measures. In this kind of trial a group of volunteers is split up randomly into two or more groups. One of the groups, for example, uses a dust-mite-proof mattress cover, while the other group does not use the cover. Then the groups are compared to see if one group has more symptoms than the other. That can show whether or not the mattress cover alone really makes a difference.
The researchers found 9 trials with about 500 participants altogether. The trials mainly looked at different measures to be used in the bedroom. HEPA air filters, anti-dust-mite sprays for beds, mattress covers, cleaning bedding and bedrooms more often, and removing soft furnishings from the bedroom (like curtains and carpets) were each tested in at least one trial. Some of the trials combined measures such as spraying the mattress and then putting on a mattress cover. Yet few people participated in most of these trials and they were error-prone. For this reason, the trials provide some indications of what might help, but do not allow any firm conclusions to be drawn for any particular measure.
Reducing house dust mites could reduce allergic symptoms – but no single method has been proven to reduce symptoms when applied alone
The only good-quality trials were done on protective mattress covers. Used alone, however, these covers were not proven to have a real impact on symptoms. Dust-mite-proof covers alone do not seem to have an advantage over normal bedding. There is also no research that shows HEPA air filters in the bedroom reduce symptoms.
Anti-dust-mite sprays with acaricides (pesticides against mites and ticks) might be able to help reduce allergic symptoms. These are sometimes used underneath mattress covers. Adverse effects were not reported in these small trials, but it is not clear how safe the use of anti-dust-mite sprays is over years. If they are used, it is very important to pay close attention to the instructions for use. As with all poisons, they need to be kept safely away from children. Anti-dust-mite sprays with acaricides are available in Germany. Yet German safety authorities point out that wherever possible, non-chemical methods against pests are preferable. There are also non-pesticide sprays, but the researchers found no trials on these.
The researchers concluded that if people want to try to reduce house dust mites, it might help to clean the house more often (wipe the floor with water, for example), change bedding more often and remove major “dust traps”. Items that attract dust might also include things you may not immediately think of, such as curtains, stuffed animals or furniture that is only partially covered with fabric. For something to be helpful in the long term, it is important that it be affordable and practical to do in daily life. This way you can make it part of your routine.