While most allergies aren’t serious and can be controlled with standard medication, some allergic reactions can lead to life-threatening complications. One of these life-threatening complications is called anaphylaxis.

Anaphylaxis is a severe, whole-body reaction that typically involves the heart and circulatory system, lungs, skin, and digestive tract. It can affect the eyes and nervous system as well.

A severe allergy attack may be initiated by food, such as peanuts, milk, wheat, or eggs. It can also be related to insect stings or certain medications.

Immediate medical attention is required to prevent the severe allergic reaction from getting worse.

Many people who are aware of their severe allergies carry a medication called epinephrine, or adrenaline. This is injected into the muscle through an “auto-injector” and is easy to use.

It acts quickly on the body to raise your blood pressure, stimulate your heart, decrease swelling, and improve breathing. It’s the treatment of choice for anaphylaxis.


If you’re experiencing anaphylaxis, administer an epinephrine shot right away. Inject yourself in the thigh for the best results.

Talk to your doctor about the timing of your injection. Some experts recommend using an epinephrine shot as soon as you realize you’ve been exposed to an allergen, rather than waiting for symptoms.

You’ll then need to proceed to the emergency room (ER) as a follow-up. At the hospital, you’ll likely be given oxygen, antihistamines, and intravenous (IV) corticosteroids — typically methylprednisolone.

You may need to be observed in the hospital in order to monitor your treatment and watch for any further reactions.

First aid for others

If you think someone else is experiencing anaphylaxis, take these immediate steps:

  • Ask someone to call for medical help. Call 911 or your local emergency services if you’re alone.
  • Ask the person whether they carry an epinephrine auto-injector. If so, assist them according to label directions. Don’t administer epinephrine to someone who hasn’t been prescribed the medication.
  • Help the person to remain calm and lie quietly with their legs elevated. If vomiting occurs, turn them onto their side to prevent choking. Don’t give them anything to drink.
  • If the person becomes unconscious and stops breathing, begin CPR, and continue until medical help arrives. Go here for step-by-step instructions for performing CPR.

Importance of medical treatment

It’s important to get medical treatment for a severe allergy attack, even if the person begins to recover.

In many instances, symptoms can improve at first but then worsen quickly after a period of time. Medical care is necessary to prevent recurrence of the attack.

The onset of anaphylaxis is relatively quick. You may experience a reaction within mere seconds of exposure to a substance that you’re allergic to. At this point, your blood pressure will decrease rapidly and your airways will constrict.

Symptoms of anaphylaxis include:

Anaphylaxis is caused by allergies — but not everyone with allergies has this severe reaction. Many people have experienced symptoms of an allergy, which may include:

Allergens that can cause your immune system to overreact include:

When you come into contact with an allergen, your body assumes it’s a foreign invader and the immune system releases substances to fight it off. These substances result in other cells releasing chemicals, which causes an allergic reaction and changes throughout the body.

In children

According to the European Centre for Allergy Research Foundation (ECARF), the most common cause of anaphylaxis in children is food allergies. Common food allergies include those to:

Children are especially vulnerable to food allergies when they’re away from home. It’s important that you let all caregivers know about your child’s food allergies.

Also, teach your child to never accept homemade baked goods or any other foods that might contain unknown ingredients.

In adults

In adults, the most common causes of anaphylaxis are foods, medications, and venom from insect bites.

You may be at risk for anaphylaxis if you’re allergic to any medications, such as aspirin, penicillin, and other antibiotics.

Anaphylaxis is a broad term for this allergic reaction. In fact, it can be broken down into subtypes. The different classifications are based on how symptoms and reactions occur.

Uniphasic reaction

This is the most common type of anaphylaxis. The onset of the reaction is rather quick, with symptoms peaking about 30 minutes after exposure to an allergen.

It’s estimated that 80 to 90 percent of all cases end up being uniphasic reactions.

Biphasic reaction

A biphasic reaction occurs after the first experience of anaphylaxis, generally between 1 to 72 hours after the initial attack. It commonly occurs within 8 to 10 hours after your first reaction occurred.

Protracted reaction

This is the longest type of reaction. In this reaction, the symptoms of anaphylaxis persist and are difficult to treat, sometimes lasting 24 hours or more without resolving completely.

This reaction is typically very uncommon. Persistent low blood pressure may occur and extended hospitalization may be necessary.

When left untreated, anaphylaxis can lead to anaphylactic shock. This is a dangerous condition where your blood pressure drops and your airways narrow and swell, limiting your breathing. Your heart can also stop during shock due to poor blood flow.

In the most severe cases, anaphylaxis can cause death. Prompt treatment with epinephrine can prevent the life-threatening effects of anaphylaxis. Learn more about the effects of anaphylaxis.

The outlook for anaphylaxis is positive when treatment measures are taken immediately. Timing here is the key. Anaphylaxis may prove fatal if it’s left untreated.

If you have severe allergies, you should always keep an epinephrine auto-injector on hand in case of exposure and anaphylaxis. Regular management with the help of an allergist can also help.

Avoid known allergens whenever possible. Also, follow up with your doctor if you suspect any sensitivity to other undiagnosed allergens.