al’ lêr gy – An abnormal immune response (allergic reaction) to a non-harmful trigger (an allergen).
Exposure to allergens does not produce allergy symptoms in non-allergic individuals, but causes mild to severe symptoms in an allergic person. These symptoms may include sneezing; watery, itchy, red eyes; a runny nose; a scratchy throat or cough. Some allergy sufferers have more symptoms. Dry, red, itchy patches of skin called eczema can be caused by allergies. A severe allergic reaction may be expressed as hives, swelling of the lips, eyes or extremities. Life-threatening allergic reactions occur when airways become swollen shut or when a rapid drop in blood pressure (shock) occurs.
There are two factors that determine if a person will have allergies: their genetic background, and their exposure to allergens. Allergies run in families. If one parent has allergies, there is about a 25 percent chance that their children will have allergies. If both parents have allergies, the likelihood goes up to about 50 percent that each child will develop allergies. The genetic background provides the potential to develop allergies; the environment provides the allergen trigger..
Anything that enters the body is potentially capable of producing an allergic response. In general, however, the most common allergic triggers are pollens (from grasses, trees, weeds), mold spores, dust mites (microscopic organisms found in house dust), insect venoms, animal danders and foods. Only two percent of the population has actual food allergies, but allergic reactions to foods are often severe and are potentially life threatening. Tobacco smoke, perfume, hair spray and the components of air pollution are generally not allergens, but their presence can make existing allergy symptoms worse.
Symptoms of a drug allergy:
- Skin rash or hives
- Facial swelling
- Shortness of breath or wheezing
- Itchy skin
Anaphylaxis is a system-wide allergic reaction that can be fatal. Listed below are some of the symptoms associated with anaphylaxis:
- Tightening of the airways and throat, causing trouble breathing
- Weak, rapid pulse
- Nausea, vomiting or diarrhea
- Shock, with a severe drop in blood pressure
It is possible to have an allergic response to a drug that in the past caused no problems. Inherited traits may play a role. People with a family history of drug allergies may be more likely to develop a drug allergy; however, the person must have had a previous exposure to the drug in order to have a true allergic reaction.
The percentage of people who have an actual food allergy ranges from 3% in adults to 8% in children. Many adverse reactions to food are categorized as an allergic reaction when in reality that is not the case at all. Other food intolerances, such as lactose intolerance, food poisoning and toxic reaction cause similar symptoms. The symptoms can be, but are not limited to: nausea, vomiting, abdominal pain or stomach cramps, diarrhea, hives, skin rash, headaches, earaches, runny nose, sneezing and in sever cases, anaphylaxis. Anaphylaxis is a system-wide allergic reaction that can be fatal. The most common foods associated with allergic symptoms are:
- Cow’s milk
- Shrimp and other shellfish
- Salads & fresh fruits
Though most food allergies occur in infants and children, they can appear at any age and can be caused by foods that have been eaten for years without problem.
The inhaled aeroallergens are: dust, animal dander, feathers, mildew and mold spores.
House dust allergy is common even in clean homes. House dust is a major cause of year-round runny or stuffy nose, itchy, watery eyes and sneezing for allergy sufferers. Dust can also make people with asthma experience wheezing, coughing and shortness of breath. A mixture of many materials, household dust contains many different things. Dust may contain dander from pet dogs or cats, tiny fibers shed from different kinds of fabric, as well as tiny particles of feathers, bacteria, food, plant and insect parts, and mold and fungus spores. It also contains many microscopic mites and their waste products