An allergy, or hypersensitivity reaction, occurs when the body's immune system overreacts to a substance that is normally harmless (allergen), such as mold, pollen, animal dander or dust mites.
The white blood cells of an allergic individual produce an antibody called immunoglobulin E (IgE), which attaches to the allergen. This triggers the release of histamine and other inflammatory chemicals that cause allergic symptoms, such as runny nose, watery eyes and hives.
Dust mites (Dermatophagoides farinae) are one of the most common indoor allergies. The mites are microscopic insects that are in the same biological family as spiders. Individuals may be allergic to chitin, a major component of the dust mite body and/or their digestive enzyme called DerP1, which is present in dust mite feces and decayed carcasses. Dead dust mites and their feces mix with dust and become airborne. When people who are allergic to dust mites inhale the dead dust mites and their byproducts, symptoms such as sneezing, runny nose and water eyes may result.
The average male dust mite lives an average of 20 to 30 days. A mated female can live up to 10 weeks, laying 60 to 100 eggs during the last five weeks of her life. In 10 weeks, a single dust mite produces about 2,000 fecal particles.
Unlike pollen, dust mites are present year-round in nearly every bedroom and home. While dust mites thrive in warm, humid environments like bedding, fabric, carpet furnishing and clothing, they are also found in dry or cold climates. Dust mites are able to survive and reproduce easily in bedding (especially in pillows) because of the humidity generated by the human body during breathing and perspiring.
According to the Asthma and Allergy Foundation of America (AAFA), the average person sheds about 1.5 grams of skin cells every day (about 0.3-0.45 kg per year), which is enough to feed roughly one million dust mites under ideal conditions.
Most dust mite allergies are mild and do not require treatment. Minimizing exposure to dust by regularly washing linens and fabric in hot water, vacuuming carpets and washing floors can help prevent reactions. However, individuals who experience frequent allergies may benefit from allergy medications, such as antihistamines, nasal sprays, decongestants and allergen immunotherapy (allergy shots).
Dust mite allergies are most common among children, but they can develop at any age. Some people outgrow their allergies as they age.
Typically, an allergic response is not triggered the first time the body encounters the allergen. The first time or several times after the body is exposed to an allergen, the immune system becomes sensitized. During this process, the body's white blood cells develop immunoglobulin E (IgE) antibodies to the dust mite allergens. Once sensitized, the antibodies quickly detect and bind to the dust mite allergens in the body. These antibodies also trigger the release of chemicals (like histamine) that cause allergic symptoms, such as runny nose, watery eyes and sneezing.
Individuals are more likely to develop allergies to dust mites if allergies run in their families. When one parent is allergic, their child has a 50% chance of having allergies. That risk jumps to 75% if both parents have allergies. While allergies to dust mites are most prevalent among children and young adults, they can develop at any age in life. Exposure to high levels of dust mites, especially at a young age, also increases the risk of developing dust mite allergies. Some people outgrow their allergies as they age.
Common allergy symptoms to dust mites include sneezing, runny nose, itchy and watery eyes, nasal congestion, postnasal drip (mucus drips from the sinuses down the throat), cough, irritability, facial pressure and pain, swollen and blue-colored skin under the eyes, as well as itchy nose, throat, or roof of the mouth.
Individuals who suffer from asthma may also experience lung congestion, wheezing or shortness of breath after exposure to dust mites. Asthmatics may be especially prone to asthma attacks at night, when sleeping in a bed infested with dust mites.
Skin test: The standard diagnostic test for allergies is a skin test. During the test, the skin is exposed to different allergy-causing substances, including dust mite byproducts. The skin is then observed for an allergic reaction. If an allergen triggers an allergic reaction to a test, the patient will develop reddening, swelling or a raised, itchy red wheal (bump) that looks similar to a mosquito bite. The healthcare provider will measure the size of the wheal and record the results. The larger the wheal, the more severe the allergy is. A skin test is typically conducted in a healthcare provider's office. Skin tests cause minimal, if any, discomfort. The needles used barely penetrate the skin's surface and will not cause bleeding.
Allergen-specific immunoglobulin (IgE) test: An allergen-specific immunoglobulin E (IgE) test, commonly referred to as a radioallergosorbent test (RAST©), may also be used to determine certain allergies. However, this test is less accurate than a skin test. It is usually performed in patients who have severe, co-existing skin diseases (like eczema or psoriasis) that cover large areas of the body. This is because the skin test is performed on the arms and back, and there may not be enough unaffected skin to perform a conclusive test.
The in vitro test is conducted outside of the body in a laboratory setting. During the procedure, a sample of blood is taken from the patient. The blood is then sent to a laboratory that performs specific IgE blood tests. The dust mite allergen is bound to an allergosorbent (paper disk). Then the patient's blood is added. If the blood contains antibodies (immunoglobulins that detect and bind to antigens) to the dust mite antigens, the blood will bind to the allergen on the disc. A radiolabelled ANTI-IgE antibody is then added to the disc to measure the level of immunoglobulin E present in the blood. The higher the radioactivity, the higher the level of IgE in the blood and the more severe the allergy.
A qualified healthcare provider will interpret the results of the test. In general, the sensitivity of these tests range from 50-90%, with the average being about 70-75%. The patient will receive test results in about 7-14 days.
General: Allergy treatment depends on the severity of symptoms. Commonly used allergy medications include antihistamines, nasal sprays, decongestants, leukotriene inhibitors and allergen immunotherapy (allergy shots). Patients should tell their healthcare providers if they are taking any drugs (prescription or over-the-counter), herbs or supplements.
Short-acting antihistamines: Short-acting antihistamines like diphenhydramine (Benadryl©) have been used to relieve mild to moderate allergy symptoms. Most short-acting antihistamines are available over-the-counter. These medications often cause drowsiness, and many have shown to blunt learning in children (even in the absence of drowsiness). However, loratadine (Claritin©), which is available over-the-counter, does not cause drowsiness or affect learning in children.
Longer-acting antihistamines: Longer-acting antihistamines like fexofenadine (Allegra©) or cetirizine (Zyrtec©) are available by prescription for mild to moderate allergy symptoms. They cause less drowsiness than short-acting antihistamines, and they are equally effective. These medications usually do not interfere with learning. Side effects may include drowsiness, dry mouth, headache, sore throat, stomach pain, vomiting or diarrhea.
Nasal corticosteroid sprays: Nasal corticosteroid sprays can effectively relieve allergy symptoms in patients who are not responding to antihistamines. Commonly prescribed corticosteroid sprays include fluticasone (Flonase©), mometasone (Nasonex©) and triamcinolone (Nasacort AQ©). Side effects may include nosebleeds, burning in the nose, runny nose, bloody mucus in the nose, cough, upset stomach, vomiting, diarrhea or dizziness.
Decongestants: Decongestants may help relieve symptoms such as nasal congestion (stuffy nose). These drugs shrink the tissues and blood vessels in the eyes and nose that swell in response to contact with an allergen. Nasal decongestant sprays like oxymetazoline (Afrin©) should not be used more than twice daily for three consecutive days because rebound nasal congestion may result. Decongestants in pill form do not cause this effect.
Cromolyn sodium: Cromolyn sodium is available as a nasal spray (Nasalcrom©) for treating hay fever. Eye drop versions of cromolyn sodium are available for itchy, bloodshot eyes. Side effects may include sore throat, bad taste in the mouth, cough, stuffy nose, burning or itching in the nose, sneezing, headache or stomach pain.
Allergen immunotherapy (allergy shots): Allergen immunotherapy, also known as allergy shots, is often used to treat patients who suffer from severe allergies, or for those who experience allergy symptoms more than three months a year. Allergen immunotherapy involves injecting increasing amounts of a diluted allergen into a patient over several months.
There are two phases of immunotherapy -
the build-up phase and the maintenance phase. During the build-up phase, allergy shots are injected into the upper arm once or twice a week for several months (typically three to six months). The dose is gradually increased until the maintenance dose is reached. The maintenance phase begins once the effective therapeutic dose is reached. This dose is different for each patient because it depends on the patient's level of allergen sensitivity and their response to immunotherapy during the build-up phase. Once the maintenance dose is reached, the patient will continue therapy every two to four weeks for two to five years or more.
Good scientific evidence
: Bromelain has been studied in various clinical studies for sinusitis with mixed results. Further research is necessary. Avoid if allergic to bromelain, pineapple, honeybee, venom, latex, birch pollen, carrots, celery, fennel, cypress pollen, grass pollen, papain, rye flour, wheat flour, or members of the Bromeliaceae
family. Use cautiously with history of bleeding disorder, stomach ulcers, heart disease, liver or kidney disease. Use caution before dental or surgical procedures or while driving or operating machinery. Avoid if pregnant or breastfeeding.
: Good scientific evidence suggests that butterbur may be effective for allergic rhinitis prevention in susceptible individuals. Comparisons of butterbur to prescription drugs, such as fexofenadine (Allegra©) and cetirizine (Zyrtec©), have reported similar efficacy. Additional studies are warranted before a firm conclusion can be made.
Avoid if allergic or hypersensitive to Petasites hybridus or other plants from the Asteraceae/Compositae family (such as ragweed, marigolds, daisies, and chrysanthemums). Raw, unprocessed butterbur plant should not be eaten due to the risk of liver or kidney damage or cancer. Avoid if pregnant or breastfeeding.
: There is good evidence from clinical studies to recommend the use of nasal irrigation in the treatment of allergic rhinitis. One study demonstrated that reflexology massage may be equally effective; however, the advantage of irrigation (i.e. inexpensive, performed at home, minimal adverse side effects) makes the technique beneficial. Methodological and statistical reporting are lacking in some of these trials. A well-conducted, randomized controlled trial, fully reporting data would make the case for allergic rhinitis stronger.
Early research suggests that nasal irrigation may help treat chronic sinusitis, with improvements in sinus-related quality of life, decreases in symptoms, and decreases in medication use. Further study is needed before a conclusion can be made.
Nasal irrigation is generally well tolerated. Use cautiously with history of frequent nosebleeds. If the irrigation liquid is hot, the nose may become irritated.
: Use of probiotic Enterococcus faecalis bacteria in hypertrophic sinusitis (sinus inflammation) may reduce frequency of relapses and the need for antibiotic therapy. Further research is necessary before a firm conclusion can be made. Probiotics are generally considered safe and well tolerated. Avoid if allergic or hypersensitive to probiotics. Use cautiously if lactose intolerant.
Unclear or conflicting scientific evidence
: There is currently insufficient available evidence on which to base recommendations for acupuncture in non-allergic rhinitis. However, studies suggest that it may offer possible benefits. Additionally, more studies are needed of stronger design to determine whether or not acupuncture offers benefit in sinusitis.
Acupuncture should be avoided in patients with heart disease, pulmonary disease, infections, bleeding disorders, medical conditions of unknown origin, or neurological disorders. Pregnant women, the elderly, diabetics, people with a history of seizures, and those receiving radiation therapy and/or taking drugs increasing bleeding risks should also avoid acupuncture.
: Despite widespread use in over-the-counter agents and vapors, there is not enough scientific evidence to recommend use of eucalyptus oil as a decongestant-expectorant (by mouth or inhaled form). Essential oils should be administered in a carrier oil to avoid toxicity. Avoid with a history of allergic dermatitis. Use cautiously if driving/operating heavy machinery. Avoid consuming essential oils. Avoid direct contact of undiluted oils with mucous membranes. Use cautiously if pregnant.
: Studies in patients with allergies found that black seed decreased subjective measures of severity of allergies. The effect of black seed for allergies is still not clear and further study is required before a conclusion can be made. Avoid with a known allergy/hypersensitivity to black seed, its constituents, black seed oil, or to members of the Ranunculaceae family. Allergic contact dermatitis has been reported after topical use of black seed or the oil from the seed.
: It has been suggested that cat's claw may help treat allergies and related respiratory diseases. However, there is currently limited scientific evidence to support this claim. More well-designed trials are needed to determine whether cat's claw is a beneficial treatment.
Avoid if allergic to cat's claw or Uncaria plants or plants in the Rubiaceae family, such as gardenia, coffee, or quinine. Avoid with history of conditions affecting the immune system (such as AIDS, HIV, some types of cancer, multiple sclerosis, tuberculosis, rheumatoid arthritis, lupus). Use cautiously with bleeding disorders or with history of stroke, or if taking drugs that may increase the risk of bleeding. Stop use two weeks before surgery/dental/diagnostic procedures with bleeding risk, and do not use immediately after these procedures. Avoid if pregnant or breastfeeding. Cat's claw may be contaminated with other Uncaria species. Reports exist of the potentially toxic Texan-grown plant Acacia gregii being substituted for cat's claw.
: Oral tricholine citrate (TRI) effectively relieved allergic rhinitis symptoms in limited available study. Further research is needed before a firm conclusion can be made. Choline is generally regarded as safe and appears to be well tolerated. Avoid if allergic to choline, lecithin, or phosphatidylcholine.
: Preliminary study suggests that ephedrine nasal spray may help treat allergic rhinitis. Additional research is needed before a recommendation can be made.
Ephedra taken by mouth can cause serious side effects, including heart attack, seizure, and stroke. Therefore, ephedrine nasal sprays should only be used in the nose. The U.S. Food and Drug Administration (FDA) has collected thousands of reports of serious toxicity linked to ephedra (including over 100 deaths). Ephedra products are banned from dietary supplements because of serious health risks, including heart attack, heart damage, breathing difficulties, and fluid retention in the lungs. Avoid with history of high blood pressure, abnormal heart rate, heart attack, stroke, seizure, eating disorders, anxiety, prostate disease, mental illness, kidney disease, stomach ulcers, heart disease, eye disease, depression, diabetes, thyroid disease, or sleep problems. Avoid if pregnant or breastfeeding.
: There is currently insufficient available evidence to recommend either for or against eucalyptus oil as a decongestant-expectorant.
Avoid if allergic to eucalyptus oil or with a history of seizure, diabetes, asthma, heart disease, abnormal heart rhythms, intestinal disorders, liver disease, kidney disease, lung disease, or the blood condition known as acute intermittent porphyria. Use caution if driving or operating machinery. A strain of bacteria found on eucalyptus may cause infection. Toxicity has been reported with oral and inhaled use.
: Currently, there is insufficient human evidence to recommend honey for the treatment of rhinoconjunctivitis. Avoid if allergic or hypersensitive to honey, pollen, celery or bees. Honey is generally considered safe in recommended doses. Avoid honey from the genus Rhododendron because it may cause a toxic reaction. Avoid in infants younger than 12 months of age. Use cautiously with antibiotics. Potentially harmful contaminants (like C. botulinum or grayanotoxins) can be found in some types of honey and should be used cautiously in pregnant or breastfeeding women.
: Several studies suggest that some horseradish constituents may offer antibiotic activity and may help treat sinusitis. Additional high-quality clinical studies are needed before a conclusion can be made. Avoid if allergic or hypersensitive to horseradish (Armoracia rusticana), its constituents, or members of the Brassicaceae family. Large oral doses may provoke allergic reactions. Use cautiously with clotting disorders, hypotension (low blood pressure), thyroid disorders, kidney disorders and inflammation, gastrointestinal conditions, and ulcers. Use cautiously if taking anticoagulants or antiplatelets (blood thinning agents), antihypertensives (blood pressure-lowering agents), anti-inflammatory agents, or thyroid hormones. Use cautiously if undergoing treatment for cancer. Avoid medicinal amounts of horseradish if pregnant or breastfeeding; based on herbal textbooks and folkloric precedent, horseradish has been used to induce abortion.
: It has been suggested that hypnotherapy may be effective for allergies. However, further research is necessary. Use cautiously with mental illnesses such as psychosis/schizophrenia, manic depression, multiple personality disorder, or dissociative disorders. Use cautiously with seizure disorders
: According to preliminary clinical study, MSM reduces symptoms associated with seasonal allergic rhinitis (SAR). However, larger controlled trials are needed to confirm these findings. Avoid if allergic or hypersensitive to MSM. Long-term effects of supplementation with MSM have not been examined. Avoid if pregnant or breastfeeding.
: Research shows that topical application of an alcoholic onion extract significantly reduced responses to allergies. Although intriguing, more research is needed in this area to establish the efficacy and dosing of topical onion extracts. Avoid if allergic or hypersensitive to onion (Allium cepa), its constituents, or members of the Lilaceae family. Use cautiously with hematologic (blood) disorders, diabetes, hypoglycemia (low blood sugar), and hypotension (low blood pressure). Use cautiously if taking anticoagulants or antiplatelets (blood thinners). Avoid medicinal doses if pregnant or breastfeeding.
: Preliminary evidence suggests some benefit of perilla extract for seasonal allergies. Further clinical trials are required before conclusions can be made. Avoid if allergic/hypersensitive to perilla or members of the Lamiaciae/Labiatae family. Use cautiously with cancer, low HDL-cholesterol, and immune disorders. Use cautiously if taking NSAIDS or barbiturates. Avoid if pregnant or breastfeeding.
: Only a few types and combinations of probiotics have been studied as a possible allergy treatment. They have been studied mostly in children, teenagers, and young adults. Further research is necessary before a firm conclusion can be made. Probiotics are generally considered safe and well tolerated. Avoid if allergic or hypersensitive to probiotics. Use cautiously if lactose intolerant.
: Research suggests that an herbal combination preparation containing sorrel, Sinupret©, may have beneficial effects in improving symptoms of sinusitis when used with antibiotics. It is not clear if these same effects would be seen with sorrel alone or what dose may be safe and effective. For allergic rhinitis, there is not enough evidence to make a conclusion at this time. More research of sorrel alone is needed.
Avoid sorrel with a known allergy to sorrel or any of its constituents. Avoid large doses of sorrel because there have been reports of toxicity and death. Many tinctures contain high levels of alcohol and should be avoided when driving or operating heavy machinery. Sorrel formulations may cause nausea or vomiting when taken with the prescription drugs metronidazole (Flagyl©) or disulfiram (Antabuse©). Avoid if pregnant or breastfeeding.
: Anti-inflammatory properties of spirulina may help improve symptoms of allergic rhinitis. However, further high-quality studies are needed to confirm these findings. Avoid if allergic or hypersensitive to spirulina or blue-green algae. Use cautiously with phenylketonuria (a genetic disorder of a liver enzyme that disrupts normal body functions), autoimmune diseases, bleeding disorders, diabetes, and osteoporosis. Use cautiously with products containing the blue-green algae species Anabaena spp., Aphanizomenon spp., and Microcystis spp.; in underweight patients or in those taking antiobesity agents or appetite suppressants; of if consuming a high-protein diet. Avoid in children or if pregnant or breastfeeding.
: For many years, a freeze-dried preparation of Urtica dioica has been prescribed by physicians and sold over-the-counter for the treatment of allergic rhinitis. Clinical trials demonstrating statistical significance over placebo and/or equivalence with other available treatments are needed to support the use of nettle in the treatment of allergic rhinitis.
Avoid if allergic or hypersensitive to nettle, the Urticaceae family or any ingredient of nettle products. Use cautiously with diabetes, bleeding disorders, and/or low sodium levels in the blood. Use cautiously with diuretics and anti-inflammatory drugs. The elderly should also use nettle cautiously. Avoid if pregnant or breastfeeding.
: Thymus extract may reduce allergy symptoms due to its potential immune stimulating effects. More clinical trials are required before recommendations can be made involving thymus extract for this use. Avoid if allergic or hypersensitive to thymus extracts. Use bovine thymus extract supplements cautiously due to potential for exposure to the virus that causes "mad cow disease." Avoid use with an organ transplant or other forms of allografts or xenografts. Avoid if receiving immunosuppressive therapy, with thymic tumors, myasthenia gravis (neuromuscular disorder), untreated hypothyroidism, or if taking hormonal therapy. Avoid if pregnant or breastfeeding; thymic extract increases human sperm motility and progression.
: Although thought to aid in reducing the nasal symptoms of allergic rhinitis, vitamin E intake may not be effective. Current evidence is limited, however, and more studies are needed before a firm conclusion can be drawn.
Avoid if allergic or hypersensitive to vitamin E. For short periods of time, vitamin E supplementation is generally considered safe at doses up to 1,000 milligrams per day. Avoid doses higher than 1,000 milligrams a day. Avoid with retinitis pigmentosa (loss of peripheral vision). Use cautiously with bleeding disorders. The recommended dose of vitamin E for pregnant women of any age is 15 milligrams; for breastfeeding women of any age, the recommended dose is 19 milligrams. Use beyond this level in pregnant women is not recommended.
Fair negative scientific evidence
: Grape seed has been used to treat immune system disorders due to its antioxidant effects. However, a well-designed human study of allergic rhinitis sufferers showed no improvement in allergy symptoms with administration of grape seed extract ingredients.
Avoid if allergic or hypersensitive to grapes or other grape compounds. Use cautiously if taking blood thinners such as warfarin, aspirin, non-steroidal anti-inflammatory drugs (NSAIDS), or anti-platelet agents. Use cautiously with bleeding disorders or if taking drugs that may increase the risk of bleeding. Use cautiously with drugs processed using the liver's "cytochrome P450" enzyme system. Use cautiously with blood pressure disorders or if taking ACE inhibitors. Avoid with disorders that increase the risk of bleeding or with active bleeding disorders (stomach ulcers, bleeding into the brain, etc.). Avoid if pregnant or breastfeeding.
Cover the bed mattress and pillows in dust-proof or allergen-impermeable covers. Regularly change bed linens, including sheets and pillow covers.
Maintain low humidity levels inside the home. A dehumidifier or air conditioner may help keep humidity low.
Regularly wash toys, such as stuffed animals, as well as linens and clothing in hot water (130 to 140 degrees Fahrenheit) and dry thoroughly. Wash items cautiously because such hot temperatures can potentially cause burns.
Keep stuffed toys away from beds.
Use a damp moth or cloth to clean dust inside the house.
Vacuum carpets and fabric-covered furniture regularly to remove dust inside the house. Use a vacuum cleaner with a double-layered microfilter bag or a high-efficiency particulate hair (HEPA) filter.
Wood, linoleum or vinyl flooring, as well as leather furniture can reduce the number of dust mites in the home. Use blinds or washable drapes instead of heavy drapery, which can harbor dust mites.
This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).
- Asthma and Allergy Foundation of America. Dust Mites. www.aafa.org. Accessed May 13, 2009.
- National Guideline Clearinghouse. www.guideline.gov. Accessed May 13, 2009.
- National Jewish Medical and Research Center. Allergies to Dust Mites. http://nationaljewish.org. Accessed May 13, 2009.
- Natural Standard: The Authority on Integrative Medicine. www.naturalstandard.com. Copyright © 2009. Accessed May 13, 2009.
- The Cleveland Clinic Health Information Center. Allergy Overview. www.clevelandclinic.org. Accessed May 13, 2009.
- University of Pennsylvania Health System. Dust Mite Allergy. www.pennhealth.com. Accessed May 13, 2009.
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