Table of ContentsView AllTable of ContentsHow Long Reactions LastImmediate vs. DelayedFactors Affecting DurationHow to Shorten a Reaction

Table of ContentsView All

View All

Table of Contents

How Long Reactions Last

Immediate vs. Delayed

Factors Affecting Duration

How to Shorten a Reaction

Allergiesare an immune system reaction to substances calledallergens. The cause a range of symptoms from a stuffy nose to itchy eyes to difficulty breathing. How long allergies last varies based on what type of allergy, length of exposure, and several other factors.This article will discuss the different types of allergies and how long they last. It will also cover factors that impact allergy duration.ProfessionalStudioImages / Getty ImagesHow Long an Allergic Reaction Could LastThe length of time an allergic reaction can last varies based on several factors. The information below discusses the type of allergic reaction and the amount of time the reaction can last.Systemic Allergic ReactionFood AllergyFood allergy symptomstypically begin a few minutes or two hours after someone eats or drinks. In some people, the onset of symptoms will disappear, and a second wave of symptoms may return one to 72 hours later. This phenomenon is called a biphasic reaction.The length of time that food allergy symptoms last will vary based on the severity of the reaction, as well as how much of the food was eaten and for how long. Symptoms may last for a few minutes up to a couple of days.Oral allergy syndromeis a type of food allergy where the mouth or throat becomes itchy after eating certain foods. It typically occurs within minutes of eating a fruit or vegetable.Seasonal AllergySeasonal allergies, sometimes calledhay fever, is a reaction to pollen, dust, or mold that tends to worsen during the spring, summer, or fall.People with seasonal allergies can experience symptoms for the entire time that they are exposed to the allergen. This can be for about six weeks during pollen seasons.If exposure to the allergen continues, then allergy symptoms can last for months.Anaphylactic Allergic ReactionAnanaphylacticallergic reactionis a severe, whole-body allergic reaction. It occurs within seconds to minutes of contact with an allergen.AnaphylaxisThe symptoms ofanaphylaxiswill peak within 30 minutes of exposure to the allergen. The symptoms can continue to last for many hours.Skin AllergyAllergiccontact dermatitisis a skin reaction to contact from an allergen. The allergic reaction typically occurs one to two days after exposure. The reaction causes arashthat can continue to be seen for weeks after the allergen is removed.This photo contains content that some people may find graphic or disturbing.See PhotoReproduced with permission from ©DermNet NZ and ©Waikato District Health Board www.dermnetnz.org 2022.Immediate vs. Delayed Allergic ReactionsThere are fourhypersensitivity classifications: types 1, 2, 3, and 4. Types 1, 2, and 3 are immediate hypersensitivity reactions that occur soon after an allergen exposure. Type 4 is classified as delayed hypersensitivity reactions that occur 24 hours or longer after allergen exposure.The most immediate reaction is a type 1 hypersensitivity reaction. It occurs when the body producesimmunoglobulin E (IgE) antibodiesto an allergen. When the IgE antibodies detect the allergen, the allergic reaction is produced within seconds to minutes.This is seen in many allergies like pollen, pet dander, and dust. IgE also can produce anaphylaxis, in which the entire body reacts to an allergen.Type 4 hypersensitivity is the second most common type of reaction. This type of reaction takes two days or more to develop. An example of this reaction is a rash to poison ivy.Type 2 hypersensitivity is an antibody-dependent reaction involving antibodies other than IgE and is not typically described as an allergy. This is a rare reaction and takes anywhere from two to 24 hours to develop. Examples of type 2 reactions areerythroblastosis fetalis,Goodpasture syndrome, andautoimmune anemias.Type 3 is an immune-complex disease and is not typically described as an allergy. It takes a couple of days to weeks to occur. Examples of type 3 reactions aresystemic lupus erythematosus (SLE)andreactive arthritis.Factors That Impact Duration of Allergic ReactionOverall, the factor that impacts the duration of an allergic reaction is the length of time someone is exposed to the allergen.An example is those with seasonal allergies, symptoms will remain as long as the pollen is circulating in the air. Or, if a person is allergic to pet dander, they will continue to have symptoms as long as they are exposed.Allergic Reaction vs. Hypersensitivity vs. IntoleranceThe terms “allergic reaction,” “hypersensitivity,” and “intolerance” are occasionally used interchangeably. However, these terms all have unique meanings.Intolerance is usually used in reference tofood intolerance. This is when the body has a difficult time digesting a certain food. This causes people to feel sick or have an upset stomach. An example of this is lactose intolerance.An allergic reaction is a clinical syndrome that is animmune systemresponse to an allergen. The term hypersensitivity is a term that describes the immune response, and an allergy is a type of hypersensitivity reaction.Ways to Shorten Allergic Reaction TimeThere are several ways to shorten an allergic reaction. The first step is to find out what is causing the allergy and remove it. In some cases, like seasonal allergies, this is not always possible.The next step to shorten an allergic reaction is to treat it with medication. There are many over-the-counter (OTC) and prescription medicines available to manage allergies. If this is a new allergy, talk to a healthcare provider about the best treatment plan.Treatments may include:Antihistamines: This common type of oral medication blocks thehistamineresponse, which causes many of the allergy symptoms. Examples include Allegra (fexofenadine), Clarinex (desloratadine), Xyzal Allergy 24HR (levocetirizine), and Zyrtec Allergy (cetirizine). Antihistamine nasal sprays and eye drops are also available.Nasal corticosteroids: This type of nasal spray reduces swelling in the nose. This minimizes congestion and runny nose. Examples include Flonase Allergy Relief (fluticasone propionate) and Nasonex 24HR Allergy (mometasone furoate).Decongestants: A decongestant nasal spray narrows blood vessels in the nose to reduce swelling and congestion. These are very effective medications. However, if used too frequently, they can cause rebound congestion. An example isAfrin (oxymetazoline).Mast cell stabilizers:This type of medication stops the body from releasing histamine. An example is Gastrocrom (cromolyn).Corticosteroid creams:This type of topical treatment reduces swelling, redness, and itching in allergic rashes.Epinephrineis used for an anaphylactic allergic reaction. If you have an epinephrine injector (EpiPenor Auvi-Q), or epinephrine nasal spray (Neffy), use it immediately, whether or not you are certain you are experiencing an allergic reaction. After using the epinephrine, seek medical attention right away as the effects wear off within 20 minutes. Anaphylaxis can return, so further treatment and observation will be necessary.SummaryAllergies can be bothersome or even life-threatening. It’s best to avoid triggers to keep symptoms away. However, that is not always possible. In these cases, there are several medications available to reduce symptoms and decrease the duration of allergies. Always talk to a healthcare provider before starting a new medication or when a new allergy arises.

Allergiesare an immune system reaction to substances calledallergens. The cause a range of symptoms from a stuffy nose to itchy eyes to difficulty breathing. How long allergies last varies based on what type of allergy, length of exposure, and several other factors.

This article will discuss the different types of allergies and how long they last. It will also cover factors that impact allergy duration.

ProfessionalStudioImages / Getty Images

Person with beard applying eye drops when walking in a park

How Long an Allergic Reaction Could Last

The length of time an allergic reaction can last varies based on several factors. The information below discusses the type of allergic reaction and the amount of time the reaction can last.

Systemic Allergic Reaction

Food Allergy

Food allergy symptomstypically begin a few minutes or two hours after someone eats or drinks. In some people, the onset of symptoms will disappear, and a second wave of symptoms may return one to 72 hours later. This phenomenon is called a biphasic reaction.

The length of time that food allergy symptoms last will vary based on the severity of the reaction, as well as how much of the food was eaten and for how long. Symptoms may last for a few minutes up to a couple of days.

Oral allergy syndromeis a type of food allergy where the mouth or throat becomes itchy after eating certain foods. It typically occurs within minutes of eating a fruit or vegetable.

Seasonal Allergy

Seasonal allergies, sometimes calledhay fever, is a reaction to pollen, dust, or mold that tends to worsen during the spring, summer, or fall.

People with seasonal allergies can experience symptoms for the entire time that they are exposed to the allergen. This can be for about six weeks during pollen seasons.If exposure to the allergen continues, then allergy symptoms can last for months.

Anaphylactic Allergic Reaction

Ananaphylacticallergic reactionis a severe, whole-body allergic reaction. It occurs within seconds to minutes of contact with an allergen.

Anaphylaxis

The symptoms ofanaphylaxiswill peak within 30 minutes of exposure to the allergen. The symptoms can continue to last for many hours.

Skin Allergy

Allergiccontact dermatitisis a skin reaction to contact from an allergen. The allergic reaction typically occurs one to two days after exposure. The reaction causes arashthat can continue to be seen for weeks after the allergen is removed.

This photo contains content that some people may find graphic or disturbing.See PhotoReproduced with permission from ©DermNet NZ and ©Waikato District Health Board www.dermnetnz.org 2022.

This photo contains content that some people may find graphic or disturbing.See Photo

This photo contains content that some people may find graphic or disturbing.

Allergic contact dermatitis on the skin

Reproduced with permission from ©DermNet NZ and ©Waikato District Health Board www.dermnetnz.org 2022.

Immediate vs. Delayed Allergic Reactions

There are fourhypersensitivity classifications: types 1, 2, 3, and 4. Types 1, 2, and 3 are immediate hypersensitivity reactions that occur soon after an allergen exposure. Type 4 is classified as delayed hypersensitivity reactions that occur 24 hours or longer after allergen exposure.

The most immediate reaction is a type 1 hypersensitivity reaction. It occurs when the body producesimmunoglobulin E (IgE) antibodiesto an allergen. When the IgE antibodies detect the allergen, the allergic reaction is produced within seconds to minutes.This is seen in many allergies like pollen, pet dander, and dust. IgE also can produce anaphylaxis, in which the entire body reacts to an allergen.

Type 4 hypersensitivity is the second most common type of reaction. This type of reaction takes two days or more to develop. An example of this reaction is a rash to poison ivy.

Type 2 hypersensitivity is an antibody-dependent reaction involving antibodies other than IgE and is not typically described as an allergy. This is a rare reaction and takes anywhere from two to 24 hours to develop. Examples of type 2 reactions areerythroblastosis fetalis,Goodpasture syndrome, andautoimmune anemias.

Type 3 is an immune-complex disease and is not typically described as an allergy. It takes a couple of days to weeks to occur. Examples of type 3 reactions aresystemic lupus erythematosus (SLE)andreactive arthritis.

Factors That Impact Duration of Allergic Reaction

Overall, the factor that impacts the duration of an allergic reaction is the length of time someone is exposed to the allergen.An example is those with seasonal allergies, symptoms will remain as long as the pollen is circulating in the air. Or, if a person is allergic to pet dander, they will continue to have symptoms as long as they are exposed.

Allergic Reaction vs. Hypersensitivity vs. IntoleranceThe terms “allergic reaction,” “hypersensitivity,” and “intolerance” are occasionally used interchangeably. However, these terms all have unique meanings.Intolerance is usually used in reference tofood intolerance. This is when the body has a difficult time digesting a certain food. This causes people to feel sick or have an upset stomach. An example of this is lactose intolerance.An allergic reaction is a clinical syndrome that is animmune systemresponse to an allergen. The term hypersensitivity is a term that describes the immune response, and an allergy is a type of hypersensitivity reaction.

Allergic Reaction vs. Hypersensitivity vs. Intolerance

The terms “allergic reaction,” “hypersensitivity,” and “intolerance” are occasionally used interchangeably. However, these terms all have unique meanings.Intolerance is usually used in reference tofood intolerance. This is when the body has a difficult time digesting a certain food. This causes people to feel sick or have an upset stomach. An example of this is lactose intolerance.An allergic reaction is a clinical syndrome that is animmune systemresponse to an allergen. The term hypersensitivity is a term that describes the immune response, and an allergy is a type of hypersensitivity reaction.

The terms “allergic reaction,” “hypersensitivity,” and “intolerance” are occasionally used interchangeably. However, these terms all have unique meanings.

Intolerance is usually used in reference tofood intolerance. This is when the body has a difficult time digesting a certain food. This causes people to feel sick or have an upset stomach. An example of this is lactose intolerance.

An allergic reaction is a clinical syndrome that is animmune systemresponse to an allergen. The term hypersensitivity is a term that describes the immune response, and an allergy is a type of hypersensitivity reaction.

Ways to Shorten Allergic Reaction Time

There are several ways to shorten an allergic reaction. The first step is to find out what is causing the allergy and remove it. In some cases, like seasonal allergies, this is not always possible.

The next step to shorten an allergic reaction is to treat it with medication. There are many over-the-counter (OTC) and prescription medicines available to manage allergies. If this is a new allergy, talk to a healthcare provider about the best treatment plan.

Treatments may include:

Epinephrineis used for an anaphylactic allergic reaction. If you have an epinephrine injector (EpiPenor Auvi-Q), or epinephrine nasal spray (Neffy), use it immediately, whether or not you are certain you are experiencing an allergic reaction. After using the epinephrine, seek medical attention right away as the effects wear off within 20 minutes. Anaphylaxis can return, so further treatment and observation will be necessary.

Summary

Allergies can be bothersome or even life-threatening. It’s best to avoid triggers to keep symptoms away. However, that is not always possible. In these cases, there are several medications available to reduce symptoms and decrease the duration of allergies. Always talk to a healthcare provider before starting a new medication or when a new allergy arises.

12 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.Pourmand A, Robinson C, Syed W, Mazer-Amirshahi M.Biphasic anaphylaxis: A review of the literature and implications for emergency management.The American Journal of Emergency Medicine. 2018;36(8):1480-1485.Food Allergy Resource & Education.Common questions.American Academy of Allergy, Asthma, & Immunology.Oral allergy syndrome.National Institutes of Health.Cold, flu, or allergy?Texas Specialty Clinics.Food allergic reaction: how long does it last?MedlinePlus.Anaphylaxis.Asthma & Allergy Network.What is anaphylaxis?MedlinePlus.Contact dermatitis.Marshall JS, Warrington R, Watson W, Kim HL.An introduction to immunology and immunopathology.Allergy, Asthma & Clinical Immunology. 2018;14(2):49. doi:10.1186/s13223-018-0278-1DermNet.Allergies explained.Asthma Allergy Foundation of America.Allergy treatments.MedlinePlus.Allergic reactions.

12 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.Pourmand A, Robinson C, Syed W, Mazer-Amirshahi M.Biphasic anaphylaxis: A review of the literature and implications for emergency management.The American Journal of Emergency Medicine. 2018;36(8):1480-1485.Food Allergy Resource & Education.Common questions.American Academy of Allergy, Asthma, & Immunology.Oral allergy syndrome.National Institutes of Health.Cold, flu, or allergy?Texas Specialty Clinics.Food allergic reaction: how long does it last?MedlinePlus.Anaphylaxis.Asthma & Allergy Network.What is anaphylaxis?MedlinePlus.Contact dermatitis.Marshall JS, Warrington R, Watson W, Kim HL.An introduction to immunology and immunopathology.Allergy, Asthma & Clinical Immunology. 2018;14(2):49. doi:10.1186/s13223-018-0278-1DermNet.Allergies explained.Asthma Allergy Foundation of America.Allergy treatments.MedlinePlus.Allergic reactions.

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.

Pourmand A, Robinson C, Syed W, Mazer-Amirshahi M.Biphasic anaphylaxis: A review of the literature and implications for emergency management.The American Journal of Emergency Medicine. 2018;36(8):1480-1485.Food Allergy Resource & Education.Common questions.American Academy of Allergy, Asthma, & Immunology.Oral allergy syndrome.National Institutes of Health.Cold, flu, or allergy?Texas Specialty Clinics.Food allergic reaction: how long does it last?MedlinePlus.Anaphylaxis.Asthma & Allergy Network.What is anaphylaxis?MedlinePlus.Contact dermatitis.Marshall JS, Warrington R, Watson W, Kim HL.An introduction to immunology and immunopathology.Allergy, Asthma & Clinical Immunology. 2018;14(2):49. doi:10.1186/s13223-018-0278-1DermNet.Allergies explained.Asthma Allergy Foundation of America.Allergy treatments.MedlinePlus.Allergic reactions.

Pourmand A, Robinson C, Syed W, Mazer-Amirshahi M.Biphasic anaphylaxis: A review of the literature and implications for emergency management.The American Journal of Emergency Medicine. 2018;36(8):1480-1485.

Food Allergy Resource & Education.Common questions.

American Academy of Allergy, Asthma, & Immunology.Oral allergy syndrome.

National Institutes of Health.Cold, flu, or allergy?

Texas Specialty Clinics.Food allergic reaction: how long does it last?

MedlinePlus.Anaphylaxis.

Asthma & Allergy Network.What is anaphylaxis?

MedlinePlus.Contact dermatitis.

Marshall JS, Warrington R, Watson W, Kim HL.An introduction to immunology and immunopathology.Allergy, Asthma & Clinical Immunology. 2018;14(2):49. doi:10.1186/s13223-018-0278-1

DermNet.Allergies explained.

Asthma Allergy Foundation of America.Allergy treatments.

MedlinePlus.Allergic reactions.

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