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Lundgren, Linnea, and Jeff Wald. "Allergy Basics." 02 May 2006. HowStuffWorks.com. <http://health.howstuffworks.com/how-allergies-work.htm> 11 May 2008.
Allergy Basics
by Linnea Lundgren and Jeff Wald, MD
Inside This Article
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Introduction: What Causes Allergic Reactions?
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Introduction: What Causes Allergic Reactions?
Whether it's runny, itchy or stuffed, your nose knows what's bothering it. But do you know what's wrong with your nasal passages? Understanding allergies isn't difficult, but it is the first step toward building a healthy alliance with your nose, eyes, lungs, and sinuses.
What Causes Allergies?
Allergies are the result of the immune system's mistaken response to a harmless substance. Normally, the immune system stands guard and defends your body against intruders that can be dangerous to your health, such as viruses and bacteria. When it does its job well, your immune system keeps you from getting sick every time an ill-intentioned germ finds its way into your body.
An autoimmune disorder is a condition in which the immune system goes bonkers by attacking the body's tissues. Rheumatoid arthritis is an example. |
When people who have allergies encounter an allergen, their immune system produces antibodies, called IgE antibodies, that are specific to that substance -- ragweed, for instance, or cat dander.
Thousands of these antibodies bind to the surface of special cells in body tissue called mast cells, which then lie in wait for your next exposure to that specific allergen. While they are waiting, these mast cells absorb many different chemicals from the blood that will aid in the body's defense; they store these chemicals in tiny granules. When you're reexposed to the allergen, the allergen binds to the IgE antibodies on the surface of the mast cells, causing the mast cells to release the chemicals. One of the chemicals, histamine, is probably familiar to you. It is one of the biggest players in the allergic response system and causes many of the reactions, such as runny nose, sneezing, and itchy and watery eyes, that we describe as allergies.
Most anti-allergy medications block the histamine from binding to its receptor and are called antihistamines. The allergic reaction can have both an early and a late phase. Typically the early phase may start within a few minutes of exposure, while the late phase may start several hours after the initial exposure. The early phase is caused by the release of those chemicals stored in the granules in the mast cells. The late phase reaction is caused by other inflammatory cells recruited into the area.
The body's first line of defense against invaders includes the nose, mouth, eyes, lungs, and stomach. When the immune system reacts to an allergen, these body parts become battlegrounds.
Signs of the battle can include one or more of the following: runny nose; sneezing; watery, swollen, or red eyes; nasal congestion; sinus inflammation and pressure; hives; rashes; itchy eyes; itchy nose; wheezing; shortness of breath; a tight feeling in the chest; difficulty breathing; coughing; diarrhea; nausea; headache; fatigue; and a general feeling of misery.
It's ironic that the immune system, designed to protect you from illness, produces symptoms that make you feel sick when it overreacts to mundane substances. But that's the nature of the allergic response. The symptoms are the unfortunate result of the immune system's overperformance. It's a perfect example of the old saying that sometimes the cure is worse than the disease.
In the next section, we will answer a question you may have asked before: What makes certain people susceptible to allergies while others get away with nary a sneeze?
This information is solely for informational purposes. IT IS NOT INTENDED TO PROVIDE MEDICAL ADVICE. Neither the Editors of Consumer Guide (R), Publications International, Ltd., the author nor publisher take responsibility for any possible consequences from any treatment, procedure, exercise, dietary modification, action or application of medication which results from reading or following the information contained in this information. The publication of this information does not constitute the practice of medicine, and this information does not replace the advice of your physician or other health care provider. Before undertaking any course of treatment, the reader must seek the advice of their physician or other health care provider.
Inside This Article
1.
Introduction: What Causes Allergic Reactions?
2.
3.
4.
5.
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Please copy/paste the following text to properly cite this How Stuff Works article:
Lundgren, Linnea, and Jeff Wald. "Allergy Basics." 02 May 2006. HowStuffWorks.com. <http://health.howstuffworks.com/how-allergies-work.htm> 11 May 2008.
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SYMPTOM CHECKER:
Abdominal Bloating Abdominal Fullness Prematurely Afte... Abdominal Lumps Abdominal Mass Abdominal Pain Abdominal Rigidity Abdominal Sounds Abdominal Swelling Abnormal Posturing Abnormal Tooth Shape Abnormally Dark Or Light Skin Absent Menstruation Absent Thirst Agitation Ambiguous Genitalia Ankle Pain Appetite Decrease Appetite Increase Apraxia Arachnodactyly Armpit Lump Autistic Behavior Babinski's Reflex Bed Wetting Belching Binge Eating Blackheads Bleeding Gums Bleeding Into The Skin Blindness Blockage Of Leg Arteries Blood In The Semen Blood in Urine Bloody Or Tarry Stools Bone Pain Or Tenderness Bounding Pulse Bowel Incontinence Breast Lump Breast Pain Breath Odor Breath Sounds Breathing - Slowed Or Stopped Breathing Difficulty Breathing Difficulty When Lying Dow... Breathing That Sounds Abnormal Broad Nasal Bridge Bulging Fontanelles Bullae Chemosis Chest Pain Chills Clammy Skin Claw Foot Claw Hand Cloudy Cornea Clubbing Of The Fingers Or Toes Cold Intolerance Coloboma Of The Iris Comedones Confusion Constipation Contracture Deformity Coughing Coughing Up Blood Crying Excessively in Infants Cyst Decerebrate Posture Decorticate Posture Decreased Consciousness Decreased Urine Output Delayed Growth Delayed or Absent Tooth Formation Depression Diarrhea Difficulty with Urination Dizziness Drooling Drowsiness Dry Eyes Dry Hair Dry Skin Ear Discharge Earache Earlobe Creases Elbow Pain Epicanthal Folds Erection Problems Erosion Excessive Or Unwanted Hair In Women Excessive Thirst Excessive Urination Excessive Urination at Night Excessively Large Fontanelles Eye Burning, Itching and Discharge Eye Pain Eye Redness Eye Slant Eyelid Drooping Eyes That Bulge Face Pain Facial Paralysis Facial Swelling Fainting Fatigue Female Sexual Dysfunction Fever Finger Pain Fingers That Change Color Flank Pain Floating Stools Focal Neurological Deficits Foot Pain Foot, Leg, And Ankle Swelling Foul Smelling Stools Frequent Or Urgent Urination Frontal Bossing Gas (Flatulence) Gastrointestinal Bleeding Genital Sores (Female) Genital Sores (Male) Groin Lumps Groin Pain Gynecomastia Hair Loss Hallucinations Hand Or Foot Spasms Hand Tremors Headache Hearing Loss Heart Murmurs And Other Sounds Heart Palpitations Heartburn Heat Intolerance Heavy, Prolonged, or Irregular Mens... Heel Pain Hemolytic Crisis Hepatomegaly Heterochromia Hiccups Hip Pain Hoarseness Or Changing Voice Hump Behind The Shoulders Hyperactivity Hyperelastic Skin Hypermobile Joints Hyperventilation Hypotonia Impaired Smell Increased Head Circumference Indigestion Infantile Reflexes Intercostal Retractions Intertrigo Irritability Itching Jaundice (Yellow Skin) Joint Pain Joint Swelling Knee Pain Leg Pain Lichenified Limited Range Of Motion Lordosis Low Nasal Bridge Lower Back Pain Macule Malaise Memory Loss Metopic Ridge Microcephaly Micrognathia Morbid Obesity Morning Sickness Moro Reflex Motormental Retardation Mouth Sores Muscle Aches Muscle Atrophy Muscle Cramps Muscle Function Loss Muscle Twitching Nail Abnormalities Nasal Congestion Nasal Discharge Nasal Flaring Natal Teeth Nausea And Vomiting Neck Lumps Neck Pain Night Blindness Nightmares Nikolsky’s Sign Nipple Discharge Nodules Nosebleed Numbness And Tingling Obesity Opisthotonos Pain During Sexual Intercourse Painful Menstrual Periods Painful Urination Pale or Clay-Colored Stools Paleness Papule Patches Patchy Skin Color Pectus Carinatum Pectus Excavatum Penis Pain Photophobia Pilonidal Dimple Pinna Abnormalities And Low-set Ear... Point Tenderness Polydactyly Polyhydramnios Poor Feeding In Infants Preauricular Tag Or Pit Premenstrual Breast Tenderness and ... Prognathism Pupils That Are Different Sizes Purpura Pustules Rapid Shallow Breathing Rash in a Child Under 2 Years Rashes Rib Cage Pain Ridged Sutures Scales Scrotal Swelling Seizures Sensorineural Deafness Separated Sutures Shin Splints Short Philtrum Short Stature Shoulder Pain Simian Crease Skeletal Limb Abnormalities Skin Blushing/flushing Skin Discoloration Skin Lumps Skin Turgor Sleeping Difficulty Sneezing Snoring Sore Throat Spasticity Speech Impairment (adult) Splenomegaly Splinter Hemorrhages Strange Behavior Stress And Anxiety Striae Subcutaneous Emphysema Sunburn Sunken Fontanelles Supernumerary Nipples Swallowing Difficulty Swallowing Pain Or Burning Sweating Sweating Decrease Swelling Swollen Glands Swollen Gums Taste Impairment Telangiectasia Tenesmus Testicle Lump Testicle Pain Tinnitus Tongue Problems Tooth Discoloration Toothaches Ulcers Uncontrollable Eye Movements Uncontrollable Movement Uncontrolled Or Slow Movement Uncoordinated Movement Unpredictable Or Jerky Movement Urinary Incontinence Urine Discoloration Vaginal Bleeding Between Periods Vaginal Bleeding In Pregnancy Vaginal Discharge Vaginal Itching Vesicles Vision Problems Vomiting Blood Walking Abnormalities Watery Eyes Weak or Absent Pulse Weakness Webbing Of The Fingers Or Toes Weight Gain Weight Loss Wheezing White Spots in the Pupil Whitehead Widely Spaced Teeth Wrinkles Wrist Pain Yawning
DISEASES AND CONDITIONS GLOSSARY:
Aarskog Syndrome Aase Syndrome Abdominal Aortic Aneurysm ABO Incompatibility Abortion - Complete Abortion - Elective Or Therapeutic Abortion - Incomplete Abortion - Infected Abortion - Threatened Abscess Acanthosis Nigricans Achalasia Achilles Tendinitis Achondrogenesis Achondroplasia Acidosis Acne Acoustic Neuroma Acoustic Trauma Acquired Platelet Function Defect Acrodermatitis Acrodysostosis Acromegaly Actinic Keratosis Actinomycosis Acute Adrenal Crisis Acute Arterial Occlusion - Kidney Acute Bilateral Obstructive Uropath... Acute Bronchitis Acute Cerebellar Ataxia Acute Cholecystitis (Gallstones) Acute Cytomegalovirus (CMV) Infecti... Acute Gouty Arthritis Acute HIV Infection Acute Interstitial Nephritis Not NS... Acute Kidney Failure Acute Lymphocytic Leukemia (ALL) Acute Mountain Sickness Acute Myeloid Leukemia Acute Nephritic Syndrome Acute Pancreatitis Acute Tubular Necrosis Acute Unilateral Obstructive Uropat... Acute Upper Airway Obstruction Addison’s Disease Adenomyosis Adhesion Adjustment Disorder Adolescent Depression Adolescent Pregnancy Adrenocortical Carcinoma Adrenoleukodystrophy Adult Still's Disease Agammaglobulinemia Age-related Hearing Loss Agoraphobia Agranulocytosis Aicardi Syndrome AIDS Albinism Alcohol Withdrawal Alcoholic Cardiomyopathy Alcoholic Ketoacidosis Alcoholic Liver Disease Alcoholic Neuropathy Alcoholism Alkalosis Alkaptonuria Allergic Conjunctivitis Allergic Rhinitis Allergic Vasculitis Allergies Allergy To Mold - Dander - Dust Alopecia Areata Alpha-1 Antitrypsin Deficiency Alport Syndrome Alström Syndrome Alveolar Abnormalities Alzheimer’s Disease Amaurosis Fugax Amblyopia Amebiasis Amebic Liver Abscess Amelogenesis Imperfecta Amenorrhea Amniotic Constriction Bands Amphetamine Or Sympathomimetic Into... Amyotrophic Lateral Sclerosis Anal Fissure Analgesic Nephropathy Anaphylaxis Anaplastic Thyroid Cancer Androgen Insensitivity Syndrome Anemia Anemia - B12 Deficiency Anemia Of Chronic Disease Anencephaly Aneurysm Aneurysm In The Brain Angina Angiodysplasia Of The Colon Angioedema Ankylosing Spondylitis Annular Pancreas Anorchia Anorectal Abscess Anorexia Nervosa Anthrax Antisocial Personality Disorder Aortic Arch Syndrome Aortic Dissection Aortic Insufficiency Aortic Stenosis Apert Syndrome Apnea Of Prematurity Apoplexy Appendicitis ARDS (acute Respiratory Distress Sy... Arrhenoblastoma of the Ovary Arrhythmias Arterial Embolism