Allergy & Immunology
Allergies are among the most common health concerns. You can be allergic to anything from foods to pets to environmental things like pollen or dust. Allergies are more likely to affect children, but they can start at any age.
Diseases & Conditions
Agammaglobulinemia
Agammaglobulinemia is an inherited disorder in which a person has very low levels of protective immune system proteins called immunoglobulins. Immunoglobulins are a type of antibody. Low levels of these...
Diseases & Conditions
Allergic conjunctivitis
The conjunctiva is a clear layer of tissue lining the eyelids and covering the white of the eye. Allergic conjunctivitis occurs when the conjunctiva becomes swollen or inflamed due to a reaction to pollen...
Diseases & Conditions
Allergic rhinitis
Allergic rhinitis is a diagnosis associated with a group of symptoms affecting the nose. These symptoms occur when you breathe in something you are allergic to, such as dust, animal dander, or pollen. Symptoms...
Diseases & Conditions
Allergies
An allergy is an immune response or reaction to substances that are usually not harmful. immune response
Diseases & Conditions
Anaphylaxis
Anaphylaxis is a life-threatening type of allergic reaction. allergic reaction
Diseases & Conditions
Angioedema
Angioedema is swelling that is similar to hives, but the swelling is under the skin instead of on the surface. hives Hives are often called welts. They are a surface swelling. It is possible to have angioedema...
Diseases & Conditions
Asthma
Asthma is a chronic disease that causes the airways of the lungs to swell and narrow. It leads to breathing difficulty such as wheezing, shortness of breath, chest tightness, and coughing.
Diseases & Conditions
Asthma in children
Asthma is a disease that causes the airways to swell and get narrow. It leads to wheezing, shortness of breath, chest tightness, and coughing. Asthma
Diseases & Conditions
Drug allergies
Drug allergies are a group of symptoms caused by an allergic reaction to a drug (medicine).
Diseases & Conditions
Food allergy
A food allergy is a type of immune response triggered by eggs, peanuts, milk, shellfish or some other specific food.
Diseases & Conditions
Graft-versus-host disease
Graft-versus-host disease (GVHD) is a potentially life-threatening complication that can occur after certain stem cell or bone marrow transplants. bone marrow transplants
Diseases & Conditions
Hereditary angioedema
Hereditary angioedema is a rare but serious problem with the immune system. The problem is passed down through families. It causes swelling, particularly of the face and airways, and intestines (causing...
Diseases & Conditions
Hives
Hives are raised, often itchy, red bumps (welts) on the surface of the skin. They can be an allergic reaction to food or medicine. They can also appear without cause.
Diseases & Conditions
Hyperimmunization
Hyperimmunization is the presence of a larger than normal number of antibodies to a specific antigen. This creates a state of immunity that is greater than normal. Immune system overactivity can cause many...
Diseases & Conditions
Hyperimmunoglobulin E syndrome
Hyperimmunoglobulin E syndrome is a rare, genetic disease. It causes problems with the skin, sinuses, lungs, bones, and teeth.
Diseases & Conditions
Immunodeficiency disorders
Immunodeficiency disorders occur when the body's immune response is reduced or absent. immune response
Diseases & Conditions
Narcolepsy
Narcolepsy is a nervous system problem that causes extreme sleepiness and attacks of daytime sleep.
Diseases & Conditions
Night terrors in children
Night terrors (sleep terrors) are a sleep disorder in which a person quickly wakes from sleep in a terrified state.
Diseases & Conditions
Nonallergic rhinopathy
Rhinitis is a condition that includes a runny nose, sneezing, and nasal stuffiness. When environmental allergies (such as hayfever) or a cold are not causing these symptoms, the condition is called nonallergic...
Diseases & Conditions
Nut allergies
A nut allergy is a type of immune response triggered by tree nuts and peanuts. Peanuts are legumes, not nuts, but many people who are allergic to peanuts are also allergic to nuts. Nut allergies are a type...
Diseases & Conditions
Obstructive sleep apnea - adults
Obstructive sleep apnea (OSA) is a problem in which your breathing pauses during sleep. This occurs because of narrowed or blocked airways.
Diseases & Conditions
Occupational asthma
Occupational asthma is a lung disorder in which substances found in the workplace cause the airways of the lungs to swell and narrow. This leads to attacks of wheezing, shortness of breath, chest tightness...
Diseases & Conditions
Restless legs syndrome
Restless legs syndrome (RLS) is a nervous system problem that causes you to feel an unstoppable urge to get up and pace or walk. You feel uncomfortable unless you move your legs. Moving stops the unpleasant...
Diseases & Conditions
Selective deficiency of IgA
Selective deficiency of IgA is the most common immune deficiency disorder. People with this disorder have a low or absent level of a blood protein called immunoglobulin A. immune deficiency disorder
Diseases & Conditions
Serum sickness
Serum sickness is a reaction that is similar to an allergy. The immune system reacts to medicines that contain proteins used to treat immune conditions. It can also react to antiserum, the liquid part of...
Diseases & Conditions
Transplant rejection
Transplant rejection is a process in which a transplant recipient's immune system attacks the transplanted organ or tissue.
Special Topics
Allergen
An allergen is a substance that can cause an allergic reaction. In some people, the immune system recognizes allergens as foreign or dangerous. As a result, the immune system reacts by making a type of...
Special Topics
Antibody
An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. Examples of antigens include microorganisms (bacteria, fungi, parasites, and viruses) and...
Special Topics
Antigen
An antigen is any substance that causes your immune system to produce antibodies against it. This means your immune system does not recognize the substance, and is trying to fight it off. antibodies An...
Special Topics
Asthma and allergy resources
Special Topics
Autoinoculation
Autoinoculation is a procedure in which cells are removed from the body, treated or medically changed, and then placed back into the body. It is done to help prevent an immune reaction or to help diagnose...
Special Topics
Immune response
The immune response is how your body recognizes and defends itself against bacteria, viruses, and substances that appear foreign and harmful.
Special Topics
Lymph system
The lymph system is a network of organs, lymph nodes, lymph ducts, and lymph vessels that make and move lymph from tissues to the bloodstream. The lymph system is a major part of the body's immune system...
Special Topics
Macrophage
A macrophage is a type of immune cell. It destroys foreign substances to protect the body from infection.
Special Topics
Pharmacogenetics
Pharmacogenetics is the study of how genes affect the way medicines work in a person. Your health care provider can use the information from pharmacogenetic testing to prescribe medicines that will work...
Tests
Abdominal wall fat pad biopsy
An abdominal wall fat pad biopsy is the removal of a small part of the abdominal wall fat pad for laboratory study of the tissue. biopsy
Tests
Allergy testing - skin
Allergy skin tests are used to find out which substances cause a person to have an allergic reaction. These substances are called allergens. allergic reaction
Tests
Anti-smooth muscle antibody
Anti-smooth muscle antibody is a blood test that detects the presence of antibodies against smooth muscle. The antibody is useful in making a diagnosis of autoimmune hepatitis. antibodies
Tests
Antibody titer blood test
Antibody titer is a laboratory test that measures the level of antibodies in a blood sample. antibodies
Tests
Antimitochondrial antibody
Antimitochondrial antibodies (AMA) are substances (antibodies) that form against mitochondria. The mitochondria are an important part of cells. They are the energy source inside the cells. These help the...
Tests
Antinuclear antibody panel
The antinuclear antibody panel is a blood test that looks at antinuclear antibodies (ANA). antibodies ANA are antibodies produced by the immune system that bind to the body's own tissues.The antinuclear...
Tests
C-reactive protein
C-reactive protein (CRP) is produced by the liver. The level of CRP rises when there is inflammation in the body. It is one of a group of proteins, called acute phase reactants that go up in response to...
Tests
C1 esterase inhibitor
C1 esterase inhibitor (C1-INH) is a protein found in the fluid part of your blood. It controls a protein called C1, which is part of the complement system. The complement system is a group of nearly 60...
Tests
Clean catch urine sample
A clean catch is a method of collecting a urine sample to be tested. The clean-catch urine method is used to prevent germs from the penis or vagina from getting into a urine sample.
Tests
Complement
Complement is a blood test that measures the activity of certain proteins in the liquid portion of your blood. The complement system is a group of nearly 60 proteins that are in blood plasma or on the surface...
Tests
Complement component 3 (C3)
Complement C3 is a blood test that measures the activity of a certain protein. This protein is part of the complement system. The complement system is a group of nearly 60 proteins that are in blood plasma...
Tests
Complement component 4
Complement component 4 is a blood test that measures the activity of a certain protein. This protein is part of the complement system. The complement system is a group of nearly 60 proteins that are found...
Tests
Cryoglobulins
Cryoglobulins are antibodies that become solid or gel-like at low temperatures in the laboratory. This article describes the blood test used to check for them. In the laboratory, cryoglobulins come out...
Tests
Immunoelectrophoresis – blood
Serum immunoelectrophoresis is a lab test that measures proteins called immunoglobulins in the blood. Immunoglobulins are proteins that function as antibodies, which fight infection. There are many types...
Tests
Immunofixation blood test
The immunofixation blood test is used to identify proteins called immunoglobulins in blood. Immunoglobulins are proteins that function as antibodies, which fight infection. There are many types of immunoglobulins...
Tests
Nitroblue tetrazolium blood test
The nitroblue tetrazolium test checks if certain immune system cells can change a colorless chemical called nitroblue tetrazolium (NBT) into a deep blue color.
Tests
Pharmacogenetic testing
Pharmacogenetic testing provides information about your genes and how they control your response to certain medicines. Your genes can affect the desired result of a drug. Your provider can use the information...
Tests
Quantitative nephelometry test
Quantitative nephelometry is a lab test to quickly and accurately measure levels of certain proteins called immunoglobulins in the blood. Immunoglobulins are antibodies that help fight infection. antibodies...
Tests
Abdominal wall fat pad biopsy
An abdominal wall fat pad biopsy is the removal of a small part of the abdominal wall fat pad for laboratory study of the tissue. biopsy
Diseases & Conditions
Agammaglobulinemia
Agammaglobulinemia is an inherited disorder in which a person has very low levels of protective immune system proteins called immunoglobulins. Immunoglobulins are a type of antibody. Low levels of these...
Special Topics
Allergen
An allergen is a substance that can cause an allergic reaction. In some people, the immune system recognizes allergens as foreign or dangerous. As a result, the immune system reacts by making a type of...
Diseases & Conditions
Allergic conjunctivitis
The conjunctiva is a clear layer of tissue lining the eyelids and covering the white of the eye. Allergic conjunctivitis occurs when the conjunctiva becomes swollen or inflamed due to a reaction to pollen...
Injury
Allergic reactions
Allergic reactions are sensitivities to substances called allergens that come into contact with the skin, nose, eyes, respiratory tract, and gastrointestinal tract. They can be breathed into the lungs,...
Diseases & Conditions
Allergic rhinitis
Allergic rhinitis is a diagnosis associated with a group of symptoms affecting the nose. These symptoms occur when you breathe in something you are allergic to, such as dust, animal dander, or pollen. Symptoms...
In-depth Report
Allergic rhinitis - InDepth
An in-depth report on the causes, diagnosis, treatment, and prevention of common nasal allergies. Nasal allergies can be associated with sinus inflammation and congestion; so the term 'allergic rhinosinusitis...
Questions To Ask Your Doctor
Allergic rhinitis - what to ask your doctor - adult
What to ask your doctor about allergic rhinitis - adult; Hay fever - what to ask your doctor - adult; Allergies - what to ask your doctor - adult; Allergic conjunctivitis - what to ask your doctor
Diseases & Conditions
Allergies
An allergy is an immune response or reaction to substances that are usually not harmful. immune response
Self-Care Instructions
Allergies, asthma, and dust
Reactive airway disease - dust; Bronchial asthma - dust; Triggers - dust
Self-Care Instructions
Allergies, asthma, and molds
Reactive airway - mold; Bronchial asthma - mold; Triggers - mold; Allergic rhinitis - pollen
Self-Care Instructions
Allergies, asthma, and pollen
Reactive airway - pollen; Bronchial asthma - pollen; Triggers - pollen; Allergic rhinitis - pollen
Discharge Instructions
Allergy shots
Allergy injections; Allergen immunotherapy
Tests
Allergy testing - skin
Allergy skin tests are used to find out which substances cause a person to have an allergic reaction. These substances are called allergens. allergic reaction
Diseases & Conditions
Anaphylaxis
Anaphylaxis is a life-threatening type of allergic reaction. allergic reaction
Diseases & Conditions
Angioedema
Angioedema is swelling that is similar to hives, but the swelling is under the skin instead of on the surface. hives Hives are often called welts. They are a surface swelling. It is possible to have angioedema...
Tests
Anti-smooth muscle antibody
Anti-smooth muscle antibody is a blood test that detects the presence of antibodies against smooth muscle. The antibody is useful in making a diagnosis of autoimmune hepatitis. antibodies
Special Topics
Antibody
An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. Examples of antigens include microorganisms (bacteria, fungi, parasites, and viruses) and...
Tests
Antibody titer blood test
Antibody titer is a laboratory test that measures the level of antibodies in a blood sample. antibodies
Special Topics
Antigen
An antigen is any substance that causes your immune system to produce antibodies against it. This means your immune system does not recognize the substance, and is trying to fight it off. antibodies An...
Self-Care Instructions
Antihistamines for allergies
Allergic rhinitis - antihistamine; Hives - antihistamine; Allergic conjunctivitis - antihistamine; Urticaria - antihistamine; Dermatitis - antihistamine; Eczema - antihistamine
Tests
Antimitochondrial antibody
Antimitochondrial antibodies (AMA) are substances (antibodies) that form against mitochondria. The mitochondria are an important part of cells. They are the energy source inside the cells. These help the...
Tests
Antinuclear antibody panel
The antinuclear antibody panel is a blood test that looks at antinuclear antibodies (ANA). antibodies ANA are antibodies produced by the immune system that bind to the body's own tissues.The antinuclear...
Diseases & Conditions
Asthma
Asthma is a chronic disease that causes the airways of the lungs to swell and narrow. It leads to breathing difficulty such as wheezing, shortness of breath, chest tightness, and coughing.
Special Topics
Asthma and allergy resources
Self-Care Instructions
Asthma and school
Asthma action plan - school; Wheezing - school; Reactive airway disease - school; Bronchial asthma - school
In-depth Report
Asthma in adults - InDepth
An in-depth report on how asthma is diagnosed, treated, and managed in adults.
Diseases & Conditions
Asthma in children
Asthma is a disease that causes the airways to swell and get narrow. It leads to wheezing, shortness of breath, chest tightness, and coughing. Asthma
In-depth Report
Asthma in children and adolescents - InDepth
An in-depth report on how asthma is diagnosed, treated, and managed in children and adolescents.
Special Topics
Autoinoculation
Autoinoculation is a procedure in which cells are removed from the body, treated or medically changed, and then placed back into the body. It is done to help prevent an immune reaction or to help diagnose...
Tests
C-reactive protein
C-reactive protein (CRP) is produced by the liver. The level of CRP rises when there is inflammation in the body. It is one of a group of proteins, called acute phase reactants that go up in response to...
Tests
C1 esterase inhibitor
C1 esterase inhibitor (C1-INH) is a protein found in the fluid part of your blood. It controls a protein called C1, which is part of the complement system. The complement system is a group of nearly 60...
Tests
Clean catch urine sample
A clean catch is a method of collecting a urine sample to be tested. The clean-catch urine method is used to prevent germs from the penis or vagina from getting into a urine sample.
Tests
Complement
Complement is a blood test that measures the activity of certain proteins in the liquid portion of your blood. The complement system is a group of nearly 60 proteins that are in blood plasma or on the surface...
Tests
Complement component 3 (C3)
Complement C3 is a blood test that measures the activity of a certain protein. This protein is part of the complement system. The complement system is a group of nearly 60 proteins that are in blood plasma...
Tests
Complement component 4
Complement component 4 is a blood test that measures the activity of a certain protein. This protein is part of the complement system. The complement system is a group of nearly 60 proteins that are found...
Tests
Cryoglobulins
Cryoglobulins are antibodies that become solid or gel-like at low temperatures in the laboratory. This article describes the blood test used to check for them. In the laboratory, cryoglobulins come out...
Diseases & Conditions
Drug allergies
Drug allergies are a group of symptoms caused by an allergic reaction to a drug (medicine).
Self-Care Instructions
Exercise-induced asthma
Wheezing - exercise-induced; Reactive airway disease - exercise; Exercise-induced bronchoconstriction
Self-Care Instructions
Exercising and asthma at school
Asthma - exercise school; Exercise - induced asthma - school
Nutrition
Food additives
Food additives are substances that become part of a food product when they are added during the processing or making of that food. "Direct" food additives are often added during processing to: Add nutrientsHelp...
Diseases & Conditions
Food allergy
A food allergy is a type of immune response triggered by eggs, peanuts, milk, shellfish or some other specific food.
Diseases & Conditions
Graft-versus-host disease
Graft-versus-host disease (GVHD) is a potentially life-threatening complication that can occur after certain stem cell or bone marrow transplants. bone marrow transplants
Diseases & Conditions
Hereditary angioedema
Hereditary angioedema is a rare but serious problem with the immune system. The problem is passed down through families. It causes swelling, particularly of the face and airways, and intestines (causing...
Diseases & Conditions
Hives
Hives are raised, often itchy, red bumps (welts) on the surface of the skin. They can be an allergic reaction to food or medicine. They can also appear without cause.
Self-Care Instructions
How to use an inhaler - no spacer
Metered-dose inhaler (MDI) administration - no spacer; Bronchial nebulizer; Wheezing - nebulizer; Reactive airway - nebulizer; COPD - nebulizer; Chronic bronchitis - nebulizer; Emphysema - nebulizer
Self-Care Instructions
How to use an inhaler - with spacer
Metered-dose inhaler (MDI) administration - with spacer; Asthma - inhaler with spacer; Reactive airway disease - inhaler with spacer; Bronchial asthma - inhaler with spacer
Diseases & Conditions
Hyperimmunization
Hyperimmunization is the presence of a larger than normal number of antibodies to a specific antigen. This creates a state of immunity that is greater than normal. Immune system overactivity can cause many...
Diseases & Conditions
Hyperimmunoglobulin E syndrome
Hyperimmunoglobulin E syndrome is a rare, genetic disease. It causes problems with the skin, sinuses, lungs, bones, and teeth.
Special Topics
Immune response
The immune response is how your body recognizes and defends itself against bacteria, viruses, and substances that appear foreign and harmful.
Diseases & Conditions
Immunodeficiency disorders
Immunodeficiency disorders occur when the body's immune response is reduced or absent. immune response
Tests
Immunoelectrophoresis – blood
Serum immunoelectrophoresis is a lab test that measures proteins called immunoglobulins in the blood. Immunoglobulins are proteins that function as antibodies, which fight infection. There are many types...
Tests
Immunofixation blood test
The immunofixation blood test is used to identify proteins called immunoglobulins in blood. Immunoglobulins are proteins that function as antibodies, which fight infection. There are many types of immunoglobulins...
Self-Care Instructions
Latex allergies - for hospital patients
Latex products - hospital; Latex allergy - hospital; Latex sensitivity - hospital; Contact dermatitis - latex allergy; Allergy - latex; Allergic reaction - latex
Special Topics
Lymph system
The lymph system is a network of organs, lymph nodes, lymph ducts, and lymph vessels that make and move lymph from tissues to the bloodstream. The lymph system is a major part of the body's immune system...
Special Topics
Macrophage
A macrophage is a type of immune cell. It destroys foreign substances to protect the body from infection.
Self-Care Instructions
Managing latex allergies at home
Latex products; Latex allergy; Latex sensitivity; Contact dermatitis - latex allergy
Diseases & Conditions
Narcolepsy
Narcolepsy is a nervous system problem that causes extreme sleepiness and attacks of daytime sleep.
In-depth Report
Narcolepsy - InDepth
An in-depth report on the causes, diagnosis, and treatment of narcolepsy.
Discharge Instructions
Nasal corticosteroid sprays
Steroid nasal sprays; Allergies - nasal corticosteroid sprays
Diseases & Conditions
Night terrors in children
Night terrors (sleep terrors) are a sleep disorder in which a person quickly wakes from sleep in a terrified state.
Tests
Nitroblue tetrazolium blood test
The nitroblue tetrazolium test checks if certain immune system cells can change a colorless chemical called nitroblue tetrazolium (NBT) into a deep blue color.
Diseases & Conditions
Nonallergic rhinopathy
Rhinitis is a condition that includes a runny nose, sneezing, and nasal stuffiness. When environmental allergies (such as hayfever) or a cold are not causing these symptoms, the condition is called nonallergic...
Diseases & Conditions
Nut allergies
A nut allergy is a type of immune response triggered by tree nuts and peanuts. Peanuts are legumes, not nuts, but many people who are allergic to peanuts are also allergic to nuts. Nut allergies are a type...
Diseases & Conditions
Obstructive sleep apnea - adults
Obstructive sleep apnea (OSA) is a problem in which your breathing pauses during sleep. This occurs because of narrowed or blocked airways.
Diseases & Conditions
Occupational asthma
Occupational asthma is a lung disorder in which substances found in the workplace cause the airways of the lungs to swell and narrow. This leads to attacks of wheezing, shortness of breath, chest tightness...
Tests
Pharmacogenetic testing
Pharmacogenetic testing provides information about your genes and how they control your response to certain medicines. Your genes can affect the desired result of a drug. Your provider can use the information...
Special Topics
Pharmacogenetics
Pharmacogenetics is the study of how genes affect the way medicines work in a person. Your health care provider can use the information from pharmacogenetic testing to prescribe medicines that will work...
Injury
Poison ivy - oak - sumac rash
Poison ivy, oak, and sumac are plants that commonly cause an allergic skin reaction. This is also called an allergic contact dermatitis. The result is most often an itchy, red rash with bumps or blisters...
Tests
Quantitative nephelometry test
Quantitative nephelometry is a lab test to quickly and accurately measure levels of certain proteins called immunoglobulins in the blood. Immunoglobulins are antibodies that help fight infection. antibodies...
Diseases & Conditions
Restless legs syndrome
Restless legs syndrome (RLS) is a nervous system problem that causes you to feel an unstoppable urge to get up and pace or walk. You feel uncomfortable unless you move your legs. Moving stops the unpleasant...
In-depth Report
Restless legs syndrome and related disorders - InDepth
An in-depth report on the causes, diagnosis, treatment, and prevention of RLS.
Diseases & Conditions
Selective deficiency of IgA
Selective deficiency of IgA is the most common immune deficiency disorder. People with this disorder have a low or absent level of a blood protein called immunoglobulin A. immune deficiency disorder
Diseases & Conditions
Serum sickness
Serum sickness is a reaction that is similar to an allergy. The immune system reacts to medicines that contain proteins used to treat immune conditions. It can also react to antiserum, the liquid part of...
Self-Care Instructions
Signs of an asthma attack
Asthma attack - signs; Reactive airway disease - asthma attack; Bronchial asthma - attack
Symptoms
Sneezing
A sneeze is a sudden, forceful, uncontrolled burst of air through the nose and mouth.
Self-Care Instructions
Stay away from asthma triggers
Asthma triggers - stay away from; Asthma triggers - avoiding; Reactive airway disease - triggers; Bronchial asthma - triggers
Diseases & Conditions
Transplant rejection
Transplant rejection is a process in which a transplant recipient's immune system attacks the transplanted organ or tissue.