What are the signs and symptoms of an allergic reaction

Quick Facts

Table of Contents Show

Tips for parents
Management and Treatment
Be S.A.F.E. Action Guide
Seek immediate medical help.
Identify the Allergen.
Follow up with a specialist.
Carry Epinephrine for emergencies.
What are six signs or symptoms of an allergic reaction?
What are 3 signs of an allergic reaction?
What are the 7 allergy symptoms?
What are the symptoms of an allergic response?

Do not ignore early symptoms.
Always take a possible reaction seriously and act quickly.
Not every reaction will always look the same; a person can have different symptoms each time.
Anaphylaxis can occur without skin symptoms or hives.
A child may describe their symptoms differently than an adult: for example “my throat is tingly” or “my tongue feels scratchy”.

An allergic reaction usually happens within minutes after being exposed to an allergen, but sometimes it can take place several hours after exposure.

Symptoms and severity of a reaction can differ each time. Keep in mind that an allergic reaction can start with mild symptoms that can get worse quickly.

Symptoms of anaphylaxis generally include two or more of the following body systems:

Skin: hives, swelling (face, lips, tongue), itching, warmth, redness
Respiratory (breathing): coughing, wheezing, shortness of breath, chest pain/tightness, throat tightness, hoarse voice, nasal congestion or hay fever-like symptoms (runny itchy nose and watery eyes, sneezing), trouble swallowing
Gastrointestinal (stomach): nausea, pain/cramps, vomiting, diarrhea
Cardiovascular (heart): paler than normal skin colour/blue colour, weak pulse, passing out, dizziness or lightheadedness, shock
Other: anxiety, sense of doom (the feeling that something bad is about to happen), headache, uterine cramps, metallic taste

However, a drop in blood pressure without other symptoms may also indicate anaphylaxis. It is important to know that anaphylaxis can occur without hives.

Symptoms in babies up to 2 years of age may be indicated by a noticeable change in the sound of their cry, drooling, spitting up of food or drink after feeding, and the uncontrolled passing of stool or urine. They may show behavioural changes such as irritability, unexpectedly become very sleepy or difficult to wake up, suddenly appear very frightened, upset emotionally, and/or want to be held or comforted.*

*Simons FER, Sampson HA. Journal of Allergy and Clinical Immunology, 2015.

Make sure to talk to your doctor about how to recognize anaphylaxis.

The most dangerous symptoms of an allergic reaction are:

Trouble breathing caused by swelling of the airways (including a severe asthma attack for people who have asthma).
A drop in blood pressure causing dizziness, light-headedness, feeling faint or weak, or passing out.

Both can lead to death if untreated.

Remember

It is not possible to predict the severity of an allergic reaction.
Don’t ignore early symptoms, even if they seem mild, especially if you have had a reaction in the past.

Tips for parents

Small children can have a hard time describing their symptoms. They may complain of a “funny feeling” in their mouth or throat. Or, they may say things like “my mouth feels funny” or “my tongue is itchy”.

Next, visit our Treating reactions page to learn how to treat allergic reactions.

Overview

In most cases, people with allergies develop mild to moderate symptoms, such as watery eyes, a runny nose or a rash. But sometimes, exposure to an allergen can cause a life-threatening allergic reaction known as anaphylaxis. This severe reaction happens when an over-release of chemicals puts the person into shock. Allergies to food, insect stings, medications and latex are most frequently associated with anaphylaxis.

A second anaphylactic reaction, known as a biphasic reaction, can occur as long as 12 hours after the initial reaction.

Call 911 and get to the nearest emergency facility at the first sign of anaphylaxis, even if you have already administered epinephrine, the drug used to treat severe allergic reactions. Just because an allergic person has never had an anaphylactic reaction in the past to an offending allergen, doesn’t mean that one won’t occur in the future. If you have had an anaphylactic reaction in the past, you are at risk of future reactions.

Find expert care with an Allergist.

Don’t let allergies or asthma hold you back.

Symptoms

Anaphylaxis symptoms occur suddenly and can progress quickly. The early symptoms may be mild, such as a runny nose, a skin rash or a “strange feeling.” These symptoms can quickly lead to more serious problems, including:

Trouble breathing
Hives or swelling
Tightness of the throat
Hoarse voice
Nausea
Vomiting
Abdominal pain
Diarrhea
Dizziness
Fainting
Low blood pressure
Rapid heart beat
Feeling of doom
Cardiac arrest

People who have had a severe allergic reaction are at risk for future reactions. Even if your first reaction is mild, future reactions might be more severe. That’s why it’s important to carry self-injectable epinephrine if you are at risk, and 911 should be dialed in the event of a very serious reaction.

The best way to understand anaphylaxis and the things that can trigger this severe allergic reaction is to see an allergist who will help you manage your condition.

Diagnosis

If you have a history of allergies and/or asthma and have previously had a severe reaction, you are at greater risk for anaphylaxis.

Allergists are specially trained to review your history of allergic reactions, conduct diagnostic tests (such as skin-prick tests, blood tests and oral food challenges) to determine your triggers, review treatment options and teach avoidance techniques. Talk with an allergist if:

You’re unsure whether you have had an anaphylactic reaction.
Your symptoms are recurring or are difficult to control.
You’re having trouble managing your condition.
More tests are needed to determine the cause of your reactions.
Desensitization or immunotherapy could be helpful in your case.
Daily medication is needed.
You need intensive education on avoidance and anaphylaxis management.
Other medical conditions complicate your treatment.

Management and Treatment

An anaphylactic reaction should be treated immediately with an injection of epinephrine (adrenaline). Doses, available by prescription, come in an auto-injector that should be kept with you at all times. Two injections may be necessary to control symptoms. Here are some tips for reducing the risk of anaphylaxis:

Know your trigger. If you’ve had anaphylaxis, it’s very important to know what triggered the reaction. An allergist can review your medical history and, if necessary, conduct diagnostic tests. The most common triggers are:
- Food: including peanuts, tree nuts such as walnuts and pecans, fish, shellfish, cow’s milk and eggs.
- Latex: found in disposable gloves, intravenous tubes, syringes, adhesive tapes and catheters. Health care workers, children with spina bifida and genitourinary abnormalities and people who work with natural latex are at higher-risk for latex-induced anaphylaxis.
- Medication: including penicillin, aspirin and non-steroidal anti-inflammatory drugs such as ibuprofen, and anesthesia.
- Insect sting: with bees, wasps, hornets, yellow jackets and fire ants being the most likely to trigger anaphylaxis.
Avoid your trigger. Avoidance is the most effective way to prevent anaphylaxis. An allergist can work with you to develop specific avoidance measures tailored specifically for your age, activities, occupation, hobbies, home environment and access to medical care. Here are some general avoidance techniques for common triggers:
- Food allergies. Be a label detective and make sure you review all food ingredient labels carefully to uncover potential allergens. When eating out, ask the restaurant how food is prepared and what ingredients are used. If you have a child with a history of anaphylaxis, it’s imperative to make sure that school personnel are informed of the child’s condition and a treatment plan is provided, including the administration of epinephrine.
- Medications. Make sure all of your doctors are aware of any reactions you’ve had to medications so that they can prescribe safe alternatives and alert you to other medications you may need to avoid. If there are no alternative medications, you may be a candidate for desensitization, a treatment that introduces a small dose of the medication you are allergic to. As your body becomes more tolerant to the medication, the dosage can be increased over time. While the treatment is effective, it’s only temporary and must be repeated if the medication is needed again in the future.
- Insect stings. To help prevent stinging insects, avoid walking barefoot in grass, drinking from open soft drink cans, wearing bright colored clothing with flowery patterns, sweet smelling perfumes, hairsprays and lotion during active insect season in late summer and early fall. An allergist can also provide a preventative treatment called venom immunotherapy (or venom allergy shots) for insect sting allergy. The treatment works by introducing gradually increasing doses of purified insect venom, and has been shown to be 90 to 98 percent effective in preventing future allergic reactions to insect stings.
Be prepared. Prompt recognition of the signs and symptoms of anaphylaxis is critical. If you unexpectedly come into contact with your trigger, you should immediately follow the emergency plan outlined by your doctor including the self-administration of epinephrine. If there is any doubt about the reaction, it is generally better to administer the epinephrine. Be sure to keep your epinephrine auto-injector up to date. If an expired auto-injector is the only one available in an emergency situation, administer it promptly anyway. Teachers and other caregivers should be informed of children who are at risk for anaphylaxis and know what to do in an allergic emergency.
Seek treatment. If a severe reaction does occur and epinephrine is administered, you should be transported to the nearest emergency facility by ambulance for additional monitoring.
Tell family and friends. Family and friends should be aware of your condition, your triggers and know how to recognize anaphylactic symptoms. If you carry epinephrine, alert them to where you keep it and how to use it.
Wear identification. Wear and/or carry identification or jewelry (bracelet or necklace) noting condition and offending allergens.
See a specialist. Allergists are specially trained to help you take control of your symptoms, conduct diagnostic tests and review treatment options so you can live the life you want.
Seek additional resources. Additional information on allergies and anaphylaxis is available on the ACAAI Web site or the Food Allergy Research & Education (FARE) at www.foodallergy.org.
In addition, helpful information can be found on the Food Allergy & Anaphylaxis Connection Team (FAACT) website www.FoodAllergyAwareness.org.

Be S.A.F.E. Action Guide

Allergists and emergency physicians have teamed up to create the Be S.A.F.E. action guide to help you remember steps to take during and after an allergic emergency.

Seek immediate medical help.

Identify the Allergen.

Think about what you might have eaten or come in contact with – food, insect sting, medication, latex – to trigger an allergic reaction. It is particularly important to identify the cause because the best way to prevent anaphylaxis is to avoid its trigger.

Follow up with a specialist.

Ask your doctor for a referral to an allergist/immunologist, a physician who specializes in treating asthma and allergies. It is important that you consult an allergist for testing, diagnosis and ongoing management of your allergic disease.

Carry Epinephrine for emergencies.

Kits containing fast-acting, self-administered epinephrine are commonly prescribed for people who are at risk of anaphylaxis. Make sure that you carry an epinephrine kit with you at all times, and that family and friends know of your condition, your triggers and how to use epinephrine. Consider wearing an emergency medical bracelet or necklace identifying yourself as a person at risk of anaphylaxis. Teachers and other caregivers should be informed of children who are at risk for anaphylaxis and know what to do in an allergic emergency.

This page was reviewed for accuracy 1/29/2018.

What are six signs or symptoms of an allergic reaction?

Symptoms.

Skin reactions, including hives and itching and flushed or pale skin..

Low blood pressure (hypotension).

Constriction of the airways and a swollen tongue or throat, which can cause wheezing and trouble breathing..

A weak and rapid pulse..

Nausea, vomiting or diarrhea..

Dizziness or fainting..

What are 3 signs of an allergic reaction?

Sneezing. Runny or stuffy nose. Itchy eyes, nose or roof of mouth. Red, swollen, watery eyes -- a condition known as allergic conjunctivitis.

What are the 7 allergy symptoms?

Some of the symptoms of an allergic reaction include:.

Itchy, watery eyes..

Itchy nose..

Sneezing..

Runny nose..

Rashes..

Hives (a rash with raised red patches).

Stomach cramps..

Vomiting..

What are the symptoms of an allergic response?

Allergic reactions (hypersensitivity reactions) are inappropriate responses of the immune system to a normally harmless substance. Usually, allergies cause sneezing, watery and itchy eyes, a runny nose, itchy skin, and rash.