Dust mite allergy is an allergic reaction to tiny bugs that live in house dust. Symptoms of dust mite allergy are like those of hay fever, such as sneezing and runny nose. Many people with dust mite allergy also have symptoms of asthma, such as wheezing and trouble breathing.

Dust mites are related to ticks and spiders. Dust mites are too small to see without a microscope. They eat skin cells that people shed.

Dust mites like places that are warm and humid. In most homes, they're in bedding, padded furniture and carpeting.

Reducing the number of dust mites in the home can help control dust mite allergy. Some people need medicines or other treatments to relieve symptoms and manage asthma.

In dust mite allergies, swelling, called inflammation, of the inside of the nose, causes:

• Sneezing.
• Runny nose.
• Itchy, red or watery eyes.
• Stuffy nose.
• Itchy nose, roof of mouth or throat.
• Mucus running down the back of the throat, called postnasal drip.
• Cough.
• Facial pressure and pain.
• Swollen, discolored skin under the eyes.
• In a child, frequent upward rubbing of the nose.

People who have a dust mite allergy and asthma also might have:

• Trouble breathing.
• Chest tightness or pain.
• A whistling or wheezing sound when breathing out.
• Trouble sleeping caused by shortness of breath, coughing or wheezing.
• Coughing or wheezing that a virus such as a cold or the flu makes worse.

A dust mite allergy can range from mild to severe. A mild case of dust mite allergy may cause a runny nose, watery eyes and sneezing. Sometimes, the condition may be ongoing, called chronic.

With a dust mite allergy, symptoms are likely to be worse while sleeping or cleaning. At those times, the dust mite allergens are more likely to be in the air.

An ongoing dust mite allergy can cause repeated sneezing and coughing; stuffy nose; and facial pressure. It also can cause a flare-up of dry, itchy skin, called eczema, or severe asthma attack.

Some symptoms of dust mite allergy, such as a runny nose or sneezing, are like those of the common cold. It can be hard to know whether the symptoms are from a cold or an allergy. If symptoms last longer than one week, it might be an allergy.

For severe symptoms, such as a badly stuffed-up nose, wheezing or trouble sleeping, call a healthcare professional. Seek emergency care for wheezing or shortness of breath that gets worse quickly or for shortness of breath with little activity.

Allergies occur when the body's protective network, called the immune system, reacts to everyday things such as pollen, pet dander or dust mites. The immune system acts as though whatever causes the allergy is harmful, even though it's not.

The immune system makes proteins called antibodies that protect from invaders that could cause illness or infection. With an allergen, the immune system causes swelling, called inflammation, in the nose or lungs. Long or regular exposure to the allergen can cause the ongoing, called chronic, inflammation linked to asthma.

The following can increase the risk of having a dust mite allergy:

• Having a family history of allergies. Having several family members who have allergies increases the risk.
• Being around dust mites. Having a lot of dust mites around, especially early in life, increases the risk.
• Being a child or a young adult. A dust mite allergy is more likely to come on during childhood or early adulthood.

For people with a dust mite allergy, being around the mites can cause:

• Sinus infections. Swelling in the nose caused by dust mite allergy can block the hollow places called sinuses. This can lead to infections of the sinuses, called sinusitis.
• Asthma. People with asthma and dust mite allergy often have trouble managing asthma symptoms. They might have asthma attacks that need treatment right away.

A healthcare professional might suspect you have a dust mite allergy based on symptoms and your answers to questions about your home.

To confirm the diagnosis, a health professional might use a tool with a light to look at the lining of your nose. If you have an allergy to something in the air, the lining of the nose might be swollen and appear discolored.

Tests might include:

• Allergy skin test. This test looks for certain allergens. An allergy specialist, called an allergist, might do the test.

  In this test, tiny amounts of allergens are scratched onto the skin of the forearm or upper back. This includes dust mites. A health care provider checks the skin for signs of allergic reactions after 15 minutes. An allergic reaction is a red, itchy bump where the allergen was put on the skin.

  The most common side effects of these skin tests are itching and redness. These side effects usually go away within 30 minutes.

• Allergy blood test. Some people can't have a skin test because they have a skin issue, or they take a medicine that can affect the results. Instead, they might have a blood test that screens for allergens, including dust mites.

The first treatment for controlling dust mite allergy is avoiding dust mites as much as possible. Being around dust mites less can lead to fewer or less-severe allergic reactions. However, it's not possible to get rid of all dust mites from the home. Medicines can help control symptoms.

Allergy medicines

The following medicines can help improve nasal allergy symptoms:

• Antihistamines. These medicines relieve itching, sneezing and runny nose. Antihistamine tablets you can get without a prescription include fexofenadine (Allegra Allergy), loratadine (Alavert, Claritin), cetirizine (Zyrtec Allergy). There are antihistamine syrups for children.

  Prescription antihistamines taken as a nasal spray include azelastine and olopatadine (Patanase).

• Corticosteroid nasal sprays. These can reduce swelling and control symptoms of hay fever. You can get these medicines without a prescription. They include fluticasone (Flonase Allergy Relief), mometasone (Nasonex 24HR Allergy), triamcinolone (Nasacort Allergy 24HR), ciclesonide (Omnaris, Zetonna) and others.
• Decongestants. These help shrink swollen tissues inside the nose and make it easier to breathe through the nose. Some allergy tablets you can get without a prescription mix an antihistamine with a decongestant.

  Decongestants can increase blood pressure. People who have high blood pressure, glaucoma or cardiovascular disease shouldn't take them. Decongestants also can make an enlarged prostate worse. Talk to a healthcare professional about whether you can safely take a decongestant.

  Decongestant nasal sprays may briefly reduce allergy symptoms. But taking decongestant spray for more than three days in a row can make nasal stuffiness worse.

• Leukotriene modifiers. These block certain immune system chemicals. A healthcare professional may prescribe the leukotriene modifier montelukast (Singulair). This comes in pill form. Possible side effects include upper respiratory infection, headache and fever. Less-common side effects include behavior or mood changes, such as feeling anxious or depressed.

Other therapies

• Immunotherapy. This is used to train your immune system not to react to an allergen. Immunotherapy involves a series of allergy shots or tablets taken under the tongue, called sublingually. One to 2 weekly shots or tablets give very small doses of what causes the allergic reaction.

  The dose increases little by little, usually during a 3- to 6-month period. That's followed by shots or tablets every four weeks for 3 to 5 years. Immunotherapy is usually used when other treatments don't help.

• Nasal irrigation. A neti pot or a specially designed squeeze bottle uses salt water to rinse mucus and from the sinuses. To make the rinse, use water that's distilled, sterile, boiled and cooled, or filtered with a filter that has an absolute pore size of 1 micron or smaller. Be sure to rinse the pot or bottle after each use with the same type of water. Leave it open to air-dry.

To reduce the number of dust mites in the home, do the following:

• Use allergen proof bedcovers. Keep mattresses and pillows in dustproof or allergen-blocking covers. These covers, made of tightly woven fabric, prevent dust mites from escaping. Cover box springs with allergen proof covers.

• Wash bedding weekly. Wash all sheets, blankets, pillowcases and bedcovers in hot water that is at least 130 F (54.4 C) to kill dust mites and remove allergens. If bedding can't be washed hot, put the items in the dryer for at least 15 minutes at a temperature above 130 F (54.4 C) to kill the mites. Then wash and dry the bedding to remove allergens.

  Freezing items for 24 hours if they can't be washed also can kill dust mites. But this won't remove the allergens.

• Keep humidity low. Maintain a relative humidity below 50% in your home. A dehumidifier or air conditioner can help keep humidity low. A tool called a hygrometer measures humidity levels. You can get a hygrometer at a hardware store.
• Choose bedding wisely. Don't use bedding that traps dust easily and is hard to clean.
• Buy washable stuffed toys. Wash them often in hot water and dry all the way. Also, keep stuffed toys off beds.
• Remove dust. Use a damp or oiled mop or rag rather than dry ones to clean up dust. This keeps dust from going into the air and coming back down.

• Vacuum regularly. Vacuuming carpeting and padded furniture removes surface dust. But vacuuming won't remove most dust mites and dust mite allergens. Use a vacuum cleaner with a double-layered microfilter bag or a high-efficiency particulate air (HEPA) filter.

  If your allergies are severe, stay out of the area being vacuumed while someone else does the work. Wait about two hours before going back in the vacuumed room.

• Cut clutter. Remove anything that collects dust from the bedroom. This includes knickknacks, tabletop ornaments, books, magazines and newspapers.
• Remove carpeting and other dust mite homes. Carpeting makes a good home for dust mites. And carpeting over concrete holds moisture that dust mites seek. If possible, replace wall-to-wall bedroom carpeting with tile, wood, linoleum or vinyl flooring. Consider getting rid of other things in bedrooms that collect dust. These include padded furniture, curtains that can't be washed and horizontal blinds.
• Install a high-efficiency media filter in the furnace and air-conditioning unit. Look for a filter with a Minimum Efficiency Reporting Value (MERV) of 11 or 12. Leave the fan on to create a whole-house air filter. Be sure to change the filter every three months.

You'll likely see someone on your primary healthcare team for your allergy symptoms. Here's some information to help you get ready for your appointment.

What you can do

• Write down any symptoms you're experiencing, including any that may seem unrelated to allergy-like symptoms.
• Write down your family's history of allergy and asthma, including the types of allergies if you know them.
• Make a list of all the medicines, vitamins or supplements you're taking, including doses.
• Ask if you should stop taking any medicine, such as an antihistamine, that could affect the results of an allergy skin test.
• Make a list of questions to ask during your appointment.

For a possible dust mite allergy, basic questions to ask include:

• What is the most likely cause of my symptoms?
• Are there other possible causes?
• Will I need allergy tests?
• Should I see an allergy specialist?
• What is the best treatment?
• I have other health conditions. How can I best manage these conditions together?
• What changes can I make at home to reduce my contact with dust mites?
• Are there brochures or other printed materials I can have? What websites do you recommend?

Be sure to ask all the questions you have.

What to expect from your doctor

You'll likely be asked a few questions, such as:

• When did your symptoms start?
• Do these symptoms bother you all year?
• Are symptoms worse at certain times of day?
• Are the symptoms worse in the bedroom or other rooms of the house?
• Do you have indoor pets? Do they go in the bedrooms?
• What kind of self-care techniques have you used? Have they helped?
• What, if anything, seems to make your symptoms worse?
• Is there dampness or water damage in the home or workplace?
• Do you have an air conditioner in the home?
• Do you have asthma?

Because a pollen might be seasonal, you may have more trouble managing your asthma only during that season. Dust mites, however, are always present. Therefore, you may not realize that your allergy makes your asthma worse. In fact, it may be a main cause.

What you can do in the meantime

If you think you have dust mite allergy, take steps to reduce house dust, mainly in your bedroom. Keep your bedroom clean, remove dust-collecting clutter and wash bedding in hot water that is at least 130 F (54.4 C).