Table of ContentsView AllTable of ContentsHow They DevelopCommon AllergensGenetic Risk FactorsLifestyle FactorsAllergy ReliefSeeking Medical CareNext in Allergies GuideNatural Allergy Relief: 12 Remedies to Try
Table of ContentsView All
View All
Table of Contents
How They Develop
Common Allergens
Genetic Risk Factors
Lifestyle Factors
Allergy Relief
Seeking Medical Care
Next in Allergies Guide
Allergies occur when a part of your immune system becomes inappropriately activated when it encounters anallergen. This does not mean that your immune system is weak. Allergies are common among children and often resolve with time. However, it’s possible to develop allergies as anadultor to have a former allergy return.
When people talk about “allergies,” they often refer toallergic rhinitis(hay fever), which can cause a stuffy and drippy nose, watery eyes, and relatedsymptomsin response to an inhaled allergen, such as pollen. However, other associated conditions have an allergic element, such asallergic asthma,atopic dermatitis(eczema), and food allergies.
This article discusses why some people develop allergies. It also explores some of the most common allergens, genetic factors contributing to allergies, and ways to find relief.
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Why Does the Body Develop Allergies?
An allergic reaction occurs when the immune system overreacts to an allergen. Scientists don’t fully understand why some people develop allergies to certain substances and others do not, but they do understand what happens in the body when you have allergies.
The most common type of allergic reaction is an IgE-mediated reaction. It involves a part of theimmune systemthat makes an antibody calledimmunoglobulin E(IgE).
When your immune cells detect an allergen, such as tree pollen, they secrete IgE antibodies that send signals to other immune cells to be on the alert for this substance in the future. If these immune cells encounter that same tree pollen again, they release substances (histamine, leukotrienes, and prostaglandins) that result in allergy symptoms.
The physiology of various allergic conditions (e.g., allergic rhinitis vs. allergic asthma) varies slightly, but they all have overlapping potential triggers, environmental factors, and genetic elements.
Other Hypersensitivity Reactions
Some chemical substances are more common than others for people to develop allergies to. The following are some of the mostcommon allergens. Many people with allergies are allergic to more than one.
Pollen
If you have seasonal allergies,pollenis likely the cause. Some vegetation—like trees in early spring—have powdery pollen that is more likely to trigger allergies. Some people are allergic to grass pollen, which causes symptoms in late spring or early summer, and weeds, which contribute to symptoms in late summer and early fall.
Mold
Mold—growth from a species of fungus—and mold spores are common allergen triggers. Mold is common in wet areas, such as basements or bathrooms, or anywhere with water leaks.But you can also encounter mold in the wild, such as beneath a pile of dead leaves.
Pet Dander
Many people areallergic to pets, specifically pet dander, the dead skin flakes of household pets like dogs and cats. Even if an animal has minimal hair and is marketed as “hypoallergenic,” you can still experience allergic symptoms.
Other Household Allergens
Dust mitesare microscopic creatures often found in upholstered furniture, bedding, and carpeting.Cockroachesare another relatively common household allergen.
Insect Stings
Wasp, bee, or fire ant stings lead to pain and swelling in most people. However, people withinsect sting allergiesexperience more serious symptoms like severe and widespread swelling where they are stung and, when very serious, anaphylaxis.
AnaphylaxisAnaphylaxisis a severe and sometimes life-threatening IgE-mediated allergic reaction. The substances the body releases during an anaphylactic allergic reaction lead to more severe symptoms, such as red welts on the skin, very low blood pressure, and airway constriction.
Anaphylaxis
Anaphylaxisis a severe and sometimes life-threatening IgE-mediated allergic reaction. The substances the body releases during an anaphylactic allergic reaction lead to more severe symptoms, such as red welts on the skin, very low blood pressure, and airway constriction.
Food
Some people also develop allergic IgE-type reactions to certainfoods, like peanuts. They might experience skin symptoms and a runny nose, or even anaphylaxis.
A true food allergy like this is different from a food intolerance, which might cause symptoms after eating a certain food. For example, people withlactose intolerancemight get an upset stomach after drinking a milkshake, but that isn’t a true allergy.
Medications
Medications can also trigger allergies in some people.Classic medication allergic reactions are IgE-mediated. However, most adverse drug reactions aren’t allergies. For example, many drugs can cause you to experience certain side effects, like mild upset stomach, but these side effects do not result from an allergy.
Some medications can cause allergic reactions more so than others, including those in the following drug classes:
Substances You Touch
Certain substances trigger allergic reactions in some people. Common triggers include:
These substances can cause a hypersensitivity immune response calledallergic contact dermatitis, leading to certain skin symptoms hours or days later.
Rarely, these exposures can trigger an IgE-based reaction and symptoms such as shortness of breath from anaphylaxis upon exposure.
A Word From VerywellThe most common type of allergic reaction is an IgE-mediated reaction. Symptoms occur within minutes after exposure to allergens. The most common types of allergic conditions are allergic rhinitis, allergic asthma, and food allergies.—JURAIRAT J. MOLINA, MD, MBA, MEDICAL EXPERT BOARD
A Word From Verywell
The most common type of allergic reaction is an IgE-mediated reaction. Symptoms occur within minutes after exposure to allergens. The most common types of allergic conditions are allergic rhinitis, allergic asthma, and food allergies.—JURAIRAT J. MOLINA, MD, MBA, MEDICAL EXPERT BOARD
The most common type of allergic reaction is an IgE-mediated reaction. Symptoms occur within minutes after exposure to allergens. The most common types of allergic conditions are allergic rhinitis, allergic asthma, and food allergies.
—JURAIRAT J. MOLINA, MD, MBA, MEDICAL EXPERT BOARD
Is There a Genetic Risk Factor for Allergies?
Scientists have discovered many genes contributing to allergy development, so there is some genetic risk. For example, a version of a gene for a specific protein involved in the immune response might increase your risk of allergies.
However, additional factors—such as your environment—can also play a role. It’s possible to develop allergies even if you don’t have a family history of allergic disease.
Other Causes: Lifestyle Factors
Pregnancy temporarily changes the way some components of the immune system work. It is possible to develop new allergies during pregnancy or experience allergies you haven’t had in a while.
Some evidence suggests that certain kinds of illness may increase the risk of allergies in the weeks following the initial diagnosis. For example, this might be the case for COVID-19, but researchers are still learning more.
Additionally, having one type of allergic disease increases the risk of developing another in the future. For example, someone who has had eczema (atopic dermatitis) during early childhood might be more likely to develop a food allergy, allergic rhinitis, or allergic asthma later on.
How to Find Relief for Allergies
Not everyone can get total relief from allergies. However, you can try different approaches to managing and, in some cases, eliminating allergy symptoms, such as:
Diseases such as allergic asthma and atopic dermatitis may require additional treatments. For example, someone with allergic asthma may need inhaled medicines, such asalbuterol, to help open their airways.Someone with atopic dermatitis might respond to medications applied to their skin, like moisturizers andcorticosteroid creams.
Additionally, anyone having an anaphylactic allergic reaction needs immediate medical treatment with epinephrine (anEpiPen).
When to Contact a Healthcare Provider
If yoususpectyou may have an allergic disease, talk with a healthcare provider. They can help diagnose you and develop and adjust your treatment plan.
Immediate Treatment for AnaphylaxisIf you have symptoms of anaphylaxis, like wheezing, throat or tongue swelling, feeling faint, or difficulty breathing, seek immediate medical attention and use an EpiPen. You should see a healthcare provider even if your symptoms decrease after using an EpiPen.
Immediate Treatment for Anaphylaxis
If you have symptoms of anaphylaxis, like wheezing, throat or tongue swelling, feeling faint, or difficulty breathing, seek immediate medical attention and use an EpiPen. You should see a healthcare provider even if your symptoms decrease after using an EpiPen.
Summary
Allergies can happen when part of your immune system becomes overactivated against specific substances called allergens. Working through an IgE antibody, future exposure to the substance leads to symptoms like a drippy nose.
Pollen, mold, pet dander, dust, insect stings, medications, and certain foods are all possible causes of allergies, and some people are allergic to more than one substance. Although genetics plays a role, scientists are not entirely sure why some people develop allergies while others don’t.
Avoiding allergy triggers is important, but it’s not always possible. Medications may help decrease symptoms, and immunotherapy (such as allergy shots) might help eliminate them.
17 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Fitzsimmons CM, Falcone FH, Dunne DW.Helminth allergens, parasite-specific IgE, and its protective role in human immunity.Front Immunol. 2014;5:61. doi:10.3389/fimmu.2014.00061Marshall JS, Warrington R, Watson W, Kim HL.An introduction to immunologyand immunopathology.Allergy Asthma Clin Immunol. 2018;14(Suppl 2):49. doi:10.1186/s13223-018-0278-1American Academy of Allergy, Asthma & Immunology.Outdoor allergens.American Academy of Allergy, Asthma & Immunology.Indoor allergens.Golden DB, Demain J, Freeman T, et al.Stinging insect hypersensitivity: a practice parameter update 2016.Ann Allergy Asthma Immunol. 2017;118(1):28-54. doi:10.1016/j.anai.2016.10.031Pflipsen MC, Vega Colon KM.Anaphylaxis: recognition and management.Am Fam Physician. 2020;102(6):355-362.Yu W, Freeland DMH, Nadeau KC.Food allergy: Immune mechanisms, diagnosis and immunotherapy.Nat Rev Immunol. 2016;16(12):751-765. doi:10.1038/nri.2016.111Warrington R, Silviu-Dan F, Wong T.Drug allergy.Allergy Asthma Clin Immunol. 2018;14(Suppl 2):60. doi:10.1186/s13223-018-0289-yNassau S, Fonacier L.Allergic contact dermatitis.Med Clin North Am. 2020;104(1):61-76. doi:10.1016/j.mcna.2019.08.012American Academy of Allergy, Asthma & Immunology.Latex allergy.Ortiz RA, Barnes KC.Genetics of allergic diseases.Immunol Allergy Clin North Am. 2015;35(1):19-44. doi:10.1016/j.iac.2014.09.014Pfaller B, Bendien S, Ditisheim A, Eiwegger T.Management of allergic diseases in pregnancy.Allergy. 2022;77(3):798-811. doi:10.1111/all.15063Oh J, Lee M, Kim M, et al.Incident allergic diseases in post-COVID-19 condition: multinational cohort studies from South Korea, Japan and the UK.Nat Commun. 2024;15(1):2830. doi:10.1038/s41467-024-47176-wMedline Plus.Fluticasone nasal spray. February 15, 2023.Pavón-Romero GF, Parra-Vargas MI, Ramírez-Jiménez F, Melgoza-Ruiz E, Serrano-Pérez NH, Teran LM.Allergen immunotherapy: Current and future trends.Cells. 2022;11(2):212. doi:10.3390/cells11020212Papapostolou N, Makris M.Allergic asthma in the era of personalized medicine.J Pers Med. 2022;12(7):1162. doi:10.3390/jpm12071162Frazier W, Bhardwaj N.Atopic dermatitis: diagnosis and treatment.Am Fam Physician. 2020;101(10):590-598.
17 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Fitzsimmons CM, Falcone FH, Dunne DW.Helminth allergens, parasite-specific IgE, and its protective role in human immunity.Front Immunol. 2014;5:61. doi:10.3389/fimmu.2014.00061Marshall JS, Warrington R, Watson W, Kim HL.An introduction to immunologyand immunopathology.Allergy Asthma Clin Immunol. 2018;14(Suppl 2):49. doi:10.1186/s13223-018-0278-1American Academy of Allergy, Asthma & Immunology.Outdoor allergens.American Academy of Allergy, Asthma & Immunology.Indoor allergens.Golden DB, Demain J, Freeman T, et al.Stinging insect hypersensitivity: a practice parameter update 2016.Ann Allergy Asthma Immunol. 2017;118(1):28-54. doi:10.1016/j.anai.2016.10.031Pflipsen MC, Vega Colon KM.Anaphylaxis: recognition and management.Am Fam Physician. 2020;102(6):355-362.Yu W, Freeland DMH, Nadeau KC.Food allergy: Immune mechanisms, diagnosis and immunotherapy.Nat Rev Immunol. 2016;16(12):751-765. doi:10.1038/nri.2016.111Warrington R, Silviu-Dan F, Wong T.Drug allergy.Allergy Asthma Clin Immunol. 2018;14(Suppl 2):60. doi:10.1186/s13223-018-0289-yNassau S, Fonacier L.Allergic contact dermatitis.Med Clin North Am. 2020;104(1):61-76. doi:10.1016/j.mcna.2019.08.012American Academy of Allergy, Asthma & Immunology.Latex allergy.Ortiz RA, Barnes KC.Genetics of allergic diseases.Immunol Allergy Clin North Am. 2015;35(1):19-44. doi:10.1016/j.iac.2014.09.014Pfaller B, Bendien S, Ditisheim A, Eiwegger T.Management of allergic diseases in pregnancy.Allergy. 2022;77(3):798-811. doi:10.1111/all.15063Oh J, Lee M, Kim M, et al.Incident allergic diseases in post-COVID-19 condition: multinational cohort studies from South Korea, Japan and the UK.Nat Commun. 2024;15(1):2830. doi:10.1038/s41467-024-47176-wMedline Plus.Fluticasone nasal spray. February 15, 2023.Pavón-Romero GF, Parra-Vargas MI, Ramírez-Jiménez F, Melgoza-Ruiz E, Serrano-Pérez NH, Teran LM.Allergen immunotherapy: Current and future trends.Cells. 2022;11(2):212. doi:10.3390/cells11020212Papapostolou N, Makris M.Allergic asthma in the era of personalized medicine.J Pers Med. 2022;12(7):1162. doi:10.3390/jpm12071162Frazier W, Bhardwaj N.Atopic dermatitis: diagnosis and treatment.Am Fam Physician. 2020;101(10):590-598.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Fitzsimmons CM, Falcone FH, Dunne DW.Helminth allergens, parasite-specific IgE, and its protective role in human immunity.Front Immunol. 2014;5:61. doi:10.3389/fimmu.2014.00061Marshall JS, Warrington R, Watson W, Kim HL.An introduction to immunologyand immunopathology.Allergy Asthma Clin Immunol. 2018;14(Suppl 2):49. doi:10.1186/s13223-018-0278-1American Academy of Allergy, Asthma & Immunology.Outdoor allergens.American Academy of Allergy, Asthma & Immunology.Indoor allergens.Golden DB, Demain J, Freeman T, et al.Stinging insect hypersensitivity: a practice parameter update 2016.Ann Allergy Asthma Immunol. 2017;118(1):28-54. doi:10.1016/j.anai.2016.10.031Pflipsen MC, Vega Colon KM.Anaphylaxis: recognition and management.Am Fam Physician. 2020;102(6):355-362.Yu W, Freeland DMH, Nadeau KC.Food allergy: Immune mechanisms, diagnosis and immunotherapy.Nat Rev Immunol. 2016;16(12):751-765. doi:10.1038/nri.2016.111Warrington R, Silviu-Dan F, Wong T.Drug allergy.Allergy Asthma Clin Immunol. 2018;14(Suppl 2):60. doi:10.1186/s13223-018-0289-yNassau S, Fonacier L.Allergic contact dermatitis.Med Clin North Am. 2020;104(1):61-76. doi:10.1016/j.mcna.2019.08.012American Academy of Allergy, Asthma & Immunology.Latex allergy.Ortiz RA, Barnes KC.Genetics of allergic diseases.Immunol Allergy Clin North Am. 2015;35(1):19-44. doi:10.1016/j.iac.2014.09.014Pfaller B, Bendien S, Ditisheim A, Eiwegger T.Management of allergic diseases in pregnancy.Allergy. 2022;77(3):798-811. doi:10.1111/all.15063Oh J, Lee M, Kim M, et al.Incident allergic diseases in post-COVID-19 condition: multinational cohort studies from South Korea, Japan and the UK.Nat Commun. 2024;15(1):2830. doi:10.1038/s41467-024-47176-wMedline Plus.Fluticasone nasal spray. February 15, 2023.Pavón-Romero GF, Parra-Vargas MI, Ramírez-Jiménez F, Melgoza-Ruiz E, Serrano-Pérez NH, Teran LM.Allergen immunotherapy: Current and future trends.Cells. 2022;11(2):212. doi:10.3390/cells11020212Papapostolou N, Makris M.Allergic asthma in the era of personalized medicine.J Pers Med. 2022;12(7):1162. doi:10.3390/jpm12071162Frazier W, Bhardwaj N.Atopic dermatitis: diagnosis and treatment.Am Fam Physician. 2020;101(10):590-598.
Fitzsimmons CM, Falcone FH, Dunne DW.Helminth allergens, parasite-specific IgE, and its protective role in human immunity.Front Immunol. 2014;5:61. doi:10.3389/fimmu.2014.00061
Marshall JS, Warrington R, Watson W, Kim HL.An introduction to immunologyand immunopathology.Allergy Asthma Clin Immunol. 2018;14(Suppl 2):49. doi:10.1186/s13223-018-0278-1
American Academy of Allergy, Asthma & Immunology.Outdoor allergens.
American Academy of Allergy, Asthma & Immunology.Indoor allergens.
Golden DB, Demain J, Freeman T, et al.Stinging insect hypersensitivity: a practice parameter update 2016.Ann Allergy Asthma Immunol. 2017;118(1):28-54. doi:10.1016/j.anai.2016.10.031
Pflipsen MC, Vega Colon KM.Anaphylaxis: recognition and management.Am Fam Physician. 2020;102(6):355-362.
Yu W, Freeland DMH, Nadeau KC.Food allergy: Immune mechanisms, diagnosis and immunotherapy.Nat Rev Immunol. 2016;16(12):751-765. doi:10.1038/nri.2016.111
Warrington R, Silviu-Dan F, Wong T.Drug allergy.Allergy Asthma Clin Immunol. 2018;14(Suppl 2):60. doi:10.1186/s13223-018-0289-y
Nassau S, Fonacier L.Allergic contact dermatitis.Med Clin North Am. 2020;104(1):61-76. doi:10.1016/j.mcna.2019.08.012
American Academy of Allergy, Asthma & Immunology.Latex allergy.
Ortiz RA, Barnes KC.Genetics of allergic diseases.Immunol Allergy Clin North Am. 2015;35(1):19-44. doi:10.1016/j.iac.2014.09.014
Pfaller B, Bendien S, Ditisheim A, Eiwegger T.Management of allergic diseases in pregnancy.Allergy. 2022;77(3):798-811. doi:10.1111/all.15063
Oh J, Lee M, Kim M, et al.Incident allergic diseases in post-COVID-19 condition: multinational cohort studies from South Korea, Japan and the UK.Nat Commun. 2024;15(1):2830. doi:10.1038/s41467-024-47176-w
Medline Plus.Fluticasone nasal spray. February 15, 2023.
Pavón-Romero GF, Parra-Vargas MI, Ramírez-Jiménez F, Melgoza-Ruiz E, Serrano-Pérez NH, Teran LM.Allergen immunotherapy: Current and future trends.Cells. 2022;11(2):212. doi:10.3390/cells11020212
Papapostolou N, Makris M.Allergic asthma in the era of personalized medicine.J Pers Med. 2022;12(7):1162. doi:10.3390/jpm12071162
Frazier W, Bhardwaj N.Atopic dermatitis: diagnosis and treatment.Am Fam Physician. 2020;101(10):590-598.
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