immune disorders
Overview of Allergic Reactions
Prevention of Allergic Reactions
Avoiding or removing an allergen, if possible, is the best approach. Avoiding an allergen may involve the following: Stopping a drug Keeping pets out of the house or limiting them to certain rooms Using high-efficiency particulate air (HEPA) vacuums and filters Not eating a particular food For people with severe seasonal allergies, possibly moving to an area that does not have the allergen Removing or replacing items that collect dust, such as upholstered furniture, carpets, and knickknacks Covering mattresses and pillows with finely woven fabrics that cannot be penetrated by dust mites and allergen particles Using synthetic-fiber pillows Frequently washing bed sheets, pillowcases, and blankets in hot water Frequently cleaning the house, including dusting, vacuuming, and wet-mopping Using air conditioners and dehumidifiers in basements and other damp rooms Treating homes with heat-steam Exterminating cockroaches People with allergies should avoid or minimize exposure to certain other irritants that can make allergic symptoms worse or cause breathing problems. These irritants include the following: Cigarette smoke Strong odors Irritating fumes Air pollution Cold temperatures High humidity Allergen immunotherapy, usually allergy shots (injections), can be given to desensitize people to the allergen when some allergens, especially airborne allergens, cannot be avoided and the drugs used to treat allergic reactions are ineffective. With allergen immunotherapy, allergic reactions can be prevented or reduced in number and/or severity. However, allergen immunotherapy is not always effective. Some people and some allergies tend to respond better than others. Immunotherapy is used most often for allergies to Pollens House dust mites Molds Venom of stinging insects When people are allergic to unavoidable allergens, such as insect venom, immunotherapy helps prevent Anaphylactic Reactions . Sometimes it is used for allergies to animal dander, but such treatment is unlikely to be useful. Immunotherapy for peanut allergy is available, and immunotherapy for other food allergies is being studied. Immunotherapy is not used when the allergen, such as penicillin and other drugs, can be avoided. However, if people need to take a drug that they are allergic to, immunotherapy, closely monitored by a doctor, can be done to desensitize them. In immunotherapy, tiny amounts of the allergen are either injected under the skin or given by mouth, depending on the specific allergen. The first dose is so small that even an allergic person does not react to it. However, the small dose starts to get the person's immune system used to the allergen. Then the dose is gradually increased. Each increase is so small that the immune system still does not react. The dose is increased until the person is not reacting to the same amount of allergen that once caused symptoms. This dose is their maintenance dose. A gradual increase is necessary because exposure to too much allergen too soon can cause an allergic reaction. Injections are usually given once or twice a week until the maintenance dose is reached. Then injections are usually given every 2 to 4 weeks. The procedure is most effective when maintenance injections are continued throughout the year, even for seasonal allergies. Because immunotherapy injections occasionally causes dangerous allergic reactions, people remain in the doctor’s office for at least 30 minutes afterward. If they have mild reactions to the immunotherapy (such as sneezing, coughing, flushing, tingling sensations, itching, chest tightness, wheezing, and hives), a drug—usually an antihistamine, such asdiphenhydramineorloratadine—may help. For more severe reactions,epinephrine(adrenaline) is injected. Alternatively, doses of the allergen may be placed under the tongue (sublingual) and held there for a few minutes, then swallowed. The dose is gradually increased, as for injections. The sublingual technique is relatively new, and how often the dose should be given has not been established. It ranges from every day to 3 times a week. Extracts for grass pollen, ragweed, or house dust mite, placed under the tongue, can be used to help prevent Allergic Rhinitis . Immunotherapy for peanut allergy may also be given by mouth. The person receives the first several doses of the allergen over the course of a single day while in a doctor's office or clinic. The person then takes the allergen at home. Each time the dose is increased, the first dose of the higher dosage is given under a doctor's supervision. Allergen immunotherapy may take 3 years to complete. People who develop allergies again may need another longer course (sometimes 5 years or more) of immunotherapy. 