Table of ContentsView AllTable of ContentsFrequent SymptomsRare SymptomsComplicationsWhen to See a DoctorFrequently Asked QuestionsNext in Anaphylaxis GuideCauses and Risk Factors of Anaphylaxis

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Table of Contents

Frequent Symptoms

Rare Symptoms

Complications

When to See a Doctor

Frequently Asked Questions

Next in Anaphylaxis Guide

Anaphylaxisis a sudden and severe allergic reaction that involves more than one body system. It is a life-threatening medical emergency.You will often have skin reactions and shortness of breath, which can develop into anaphylacticshockwith a drop in blood pressure. Learn how to identify an anaphylactic reaction so you can seek immediate medical care.

anaphylaxis symptoms

What to Watch ForTo identify anaphylactic shock, first look for symptoms of allergy which include:ItchingRed, raised, blotchy skin, seen in 90 percent of casesWheezing or shortness of breath, seen in 70 percent of cases

What to Watch For

To identify anaphylactic shock, first look for symptoms of allergy which include:ItchingRed, raised, blotchy skin, seen in 90 percent of casesWheezing or shortness of breath, seen in 70 percent of cases

To identify anaphylactic shock, first look for symptoms of allergy which include:

Symptoms can be seen in many parts of the body:

Anaphylactic Shock

Anaphylaxis becomes anaphylactic shock when a person shows signs oflow blood pressure:

Anaphylactic shock often includesshortness of breath. A person doesn’t always have trouble breathing, but if the symptom is present, it’s a good indicator that the allergic reaction is turning into anaphylaxis.

Signs of Anaphylactic ShockSome of the telltale signs include:Unable to speak more than one or two wordsSitting straight up or with hands on kneesGasping for breathPursing lips to breatheUsing neck muscles to take breaths

Signs of Anaphylactic Shock

Some of the telltale signs include:Unable to speak more than one or two wordsSitting straight up or with hands on kneesGasping for breathPursing lips to breatheUsing neck muscles to take breaths

Some of the telltale signs include:

Allergen Exposure as a Sign

It’s easier to identify the signs and symptoms of anaphylactic shock if there is a known allergen exposure. For instance, those with allergies tobee stingswill usually know they’ve been stung.

Anyone who’s had allergic reactions in the past should be aware of any symptoms, even if no allergen exposure has been identified. For example, people with food allergies are more likely to have anaphylaxis while eating even when they don’t think they’re eating the food they are allergic to.

If someone is wearing medical alert jewelry that indicates an allergy, that can help identify the cause of the symptoms.

An episode of anaphylaxis typically begins within 5 to 30 minutes of coming into contact with the allergen to which you are allergic, though it can take more than an hour.However, there are atypical patterns.

Biphasic anaphylaxis is seen in up to 20 percent of patients, occurring in both children and adults, though it was once thought to be rarer. In this presentation, the initial anaphylactic reaction would manifest and it would resolve, only to have the reaction return hours to days later. This is why someone may be admitted to the hospital for observation after an anaphylactic reaction. In some cases, people won’t experience the most severe symptoms of anaphylaxis, such as difficulty breathing, and thus decide not to seek medical care. However, this puts them at risk for a biphasic reaction, which can lead to severe consequences.

A study of pediatric cases published in 2015 found a higher incidence in children of age 6 to 9. They were more likely to have been treated with more than one dose of epinephrine, indicating they had a more severe reaction. They were also more likely to have had a delay in getting treatment with epinephrine or arriving at an emergency department.

Protracted anaphylaxis is seen rarely. In this case, the symptoms can last from several days to over a week without clearly resolving completely.

How Long Do Allergic Reactions Last?

Anaphylaxis can result in death if not treated. A myocardial infarction or atrial fibrillation can develop during anaphylaxis, and these cardiac risks are greater in patients over the age of 50.

Epinephrine is the drug of choice to treat anaphylaxis, but it carries a risk of overdose and of triggering cardiovascular complications. In older patients, some research suggests it is safer to administer intramuscular injections rather than intravenous epinephrine.

If you have any symptoms of anaphylaxis, get to medical care immediately. It is appropriate to call 911 for emergency treatment.

Don’t wait to summon emergency care. The reaction can progress rapidly. Hives can turn into anaphylactic shock in minutes. If you are alone, you risk becoming unconscious before you can call for care.

If you know you are at risk of anaphylaxis from an allergy, call for emergency medical care as soon as you know you have been exposed. Even if you use an epinephrine self-injector, you will need emergency treatment.

Learn MoreCauses and Risk Factors of Anaphylaxis

Anaphylaxis usually occurs between five to 30 minutes after coming into contact with an allergen. In some cases, it can take up to an hour or longer.Some people have delayed anaphylaxis and only experience symptoms several days later. Others have biphasic anaphylaxis, in which initial mild symptoms appear to resolve, only to return more severely within hours or days.

The first line of treatment for anaphylaxis is an injection ofepinephrine, which relaxes smooth muscles and increases blood circulation.Cardiopulmonary resuscitation (CPR)may be needed if the affected person stops breathing. Other treatments may include:High-flow oxygen therapyIntravenousantihistaminesto temper the allergic responseIntravenouscorticosteroidsto temper the overall immune responseA beta-agonist like albuterol to ease breathingLearn MoreHow Anaphylaxis Is Treated

The first line of treatment for anaphylaxis is an injection ofepinephrine, which relaxes smooth muscles and increases blood circulation.Cardiopulmonary resuscitation (CPR)may be needed if the affected person stops breathing. Other treatments may include:High-flow oxygen therapyIntravenousantihistaminesto temper the allergic responseIntravenouscorticosteroidsto temper the overall immune responseA beta-agonist like albuterol to ease breathing

The first line of treatment for anaphylaxis is an injection ofepinephrine, which relaxes smooth muscles and increases blood circulation.Cardiopulmonary resuscitation (CPR)may be needed if the affected person stops breathing. Other treatments may include:

Learn MoreHow Anaphylaxis Is Treated

If treated early and appropriately, anaphylaxis can usually improve within a few hours (although you may be admitted to the hospital for overnightobservation). In severe cases, recovery may take several days. If not treated appropriately, anaphylaxis can cause permanent heart, brain, lung, and kidney injury.

Anyone with a history of anaphylaxis should carry an anaphylaxis kit, which includes an epinephrine auto-injector (called anEpiPen) and sometimes a strong oral antihistamine likediphenhydramine. You may also be advised to carry an anaphylaxis kit as well as a medical ID bracelet if you have a history of severe allergies. Anallergistcan advise you if you need one.

5 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.American Academy of Allergy, Asthma & Immunology.Anaphylaxis.Alqurashi W, Stiell I, Chan K, Neto G, Alsadoon A, Wells G.Epidemiology and clinical predictors of biphasic reactions in children with anaphylaxis.Annals of Allergy, Asthma & Immunology. 2015;115(3):217-223.e2. doi:10.1016/j.anai.2015.05.013Campbell RL, Bellolio MF, Knutson BD, et al.Epinephrine in anaphylaxis: Higher risk of cardiovascular complications and overdose after administration of intravenous bolus epinephrine compared with intramuscular epinephrine.J Allergy Clin Immunol Pract. 2015;3(1):76-80. doi:10.1016/j.jaip.2014.06.007Fischer D, Vander Leek TK, Ellis AK, Kim H.Anaphylaxis.Allergy Asthma Clin Immunol. 2018;14(S2):54. doi:10.1186/s13223-018-0283-4Kim SY, Kim MH, Cho YJ.Different clinical features of anaphylaxis according to cause and risk factors for severe reactions.Allergol Int. 2018;67(1):96-102. doi:10.1016/j.alit.2017.05.005Additional ReadingCampbell RL, Hagan JB, Li JT, et al.Anaphylaxis in emergency department patients 50 or 65 years or older.Annals of Allergy, Asthma & Immunology. 2011;106(5):401-406. doi:10.1016/j.anai.2011.01.011Oya S, Nakamori T, Kinoshita H.Incidence and characteristics of biphasic and protracted anaphylaxis: Evaluation of 114 inpatients.Acute Medicine & Surgery. 2014;1(4):228-233. doi:10.1002/ams2.48

5 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.American Academy of Allergy, Asthma & Immunology.Anaphylaxis.Alqurashi W, Stiell I, Chan K, Neto G, Alsadoon A, Wells G.Epidemiology and clinical predictors of biphasic reactions in children with anaphylaxis.Annals of Allergy, Asthma & Immunology. 2015;115(3):217-223.e2. doi:10.1016/j.anai.2015.05.013Campbell RL, Bellolio MF, Knutson BD, et al.Epinephrine in anaphylaxis: Higher risk of cardiovascular complications and overdose after administration of intravenous bolus epinephrine compared with intramuscular epinephrine.J Allergy Clin Immunol Pract. 2015;3(1):76-80. doi:10.1016/j.jaip.2014.06.007Fischer D, Vander Leek TK, Ellis AK, Kim H.Anaphylaxis.Allergy Asthma Clin Immunol. 2018;14(S2):54. doi:10.1186/s13223-018-0283-4Kim SY, Kim MH, Cho YJ.Different clinical features of anaphylaxis according to cause and risk factors for severe reactions.Allergol Int. 2018;67(1):96-102. doi:10.1016/j.alit.2017.05.005Additional ReadingCampbell RL, Hagan JB, Li JT, et al.Anaphylaxis in emergency department patients 50 or 65 years or older.Annals of Allergy, Asthma & Immunology. 2011;106(5):401-406. doi:10.1016/j.anai.2011.01.011Oya S, Nakamori T, Kinoshita H.Incidence and characteristics of biphasic and protracted anaphylaxis: Evaluation of 114 inpatients.Acute Medicine & Surgery. 2014;1(4):228-233. doi:10.1002/ams2.48

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.

American Academy of Allergy, Asthma & Immunology.Anaphylaxis.Alqurashi W, Stiell I, Chan K, Neto G, Alsadoon A, Wells G.Epidemiology and clinical predictors of biphasic reactions in children with anaphylaxis.Annals of Allergy, Asthma & Immunology. 2015;115(3):217-223.e2. doi:10.1016/j.anai.2015.05.013Campbell RL, Bellolio MF, Knutson BD, et al.Epinephrine in anaphylaxis: Higher risk of cardiovascular complications and overdose after administration of intravenous bolus epinephrine compared with intramuscular epinephrine.J Allergy Clin Immunol Pract. 2015;3(1):76-80. doi:10.1016/j.jaip.2014.06.007Fischer D, Vander Leek TK, Ellis AK, Kim H.Anaphylaxis.Allergy Asthma Clin Immunol. 2018;14(S2):54. doi:10.1186/s13223-018-0283-4Kim SY, Kim MH, Cho YJ.Different clinical features of anaphylaxis according to cause and risk factors for severe reactions.Allergol Int. 2018;67(1):96-102. doi:10.1016/j.alit.2017.05.005

American Academy of Allergy, Asthma & Immunology.Anaphylaxis.

Alqurashi W, Stiell I, Chan K, Neto G, Alsadoon A, Wells G.Epidemiology and clinical predictors of biphasic reactions in children with anaphylaxis.Annals of Allergy, Asthma & Immunology. 2015;115(3):217-223.e2. doi:10.1016/j.anai.2015.05.013

Campbell RL, Bellolio MF, Knutson BD, et al.Epinephrine in anaphylaxis: Higher risk of cardiovascular complications and overdose after administration of intravenous bolus epinephrine compared with intramuscular epinephrine.J Allergy Clin Immunol Pract. 2015;3(1):76-80. doi:10.1016/j.jaip.2014.06.007

Fischer D, Vander Leek TK, Ellis AK, Kim H.Anaphylaxis.Allergy Asthma Clin Immunol. 2018;14(S2):54. doi:10.1186/s13223-018-0283-4

Kim SY, Kim MH, Cho YJ.Different clinical features of anaphylaxis according to cause and risk factors for severe reactions.Allergol Int. 2018;67(1):96-102. doi:10.1016/j.alit.2017.05.005

Campbell RL, Hagan JB, Li JT, et al.Anaphylaxis in emergency department patients 50 or 65 years or older.Annals of Allergy, Asthma & Immunology. 2011;106(5):401-406. doi:10.1016/j.anai.2011.01.011Oya S, Nakamori T, Kinoshita H.Incidence and characteristics of biphasic and protracted anaphylaxis: Evaluation of 114 inpatients.Acute Medicine & Surgery. 2014;1(4):228-233. doi:10.1002/ams2.48

Campbell RL, Hagan JB, Li JT, et al.Anaphylaxis in emergency department patients 50 or 65 years or older.Annals of Allergy, Asthma & Immunology. 2011;106(5):401-406. doi:10.1016/j.anai.2011.01.011

Oya S, Nakamori T, Kinoshita H.Incidence and characteristics of biphasic and protracted anaphylaxis: Evaluation of 114 inpatients.Acute Medicine & Surgery. 2014;1(4):228-233. doi:10.1002/ams2.48

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