Your FAQ Answered by an Expert

Dr. Grace Yu currently teaches and practices at the San Jose-O’Connor Hospital in San Jose, CA. She attended Albert Einstein College of Medicine and Stanford School of Medicine as well as receiving her undergraduate degree from Harvard University. Anaphylaxis and extreme allergic reactions can have life-threatening implications. Get answers to some common questions about this serious condition.

What is anaphylaxis?

Anaphylaxis is a life-threatening allergic reaction that occurs upon exposure to an allergen.

What are the symptoms of anaphylaxis?

Anaphylaxis occurs when one’s immune system thinks of a normally harmless substance, such as a food, as a foreign invader. The body will do whatever it can to try to remove the allergen from the body. Typical symptoms include itchy red skin; coughing; vomiting; sneezing; and watery, red eyes. These symptoms are pathways through which the body tries to remove the allergen from the body. Vomiting, for example, is the clearest example of how the body expels a food allergen from the body. Unfortunately anaphylaxis, when it involves difficulty breathing or low blood pressure, can result in death.

What are some of the factors that determine the severity of a person’s anaphylactic reaction?

The severity of the reaction depends on a number of factors, including the dose of the allergen and the route in which the allergen enters the body. Let’s take the example of peanut allergy. If a peanut-allergic person ingests a speck of peanut, they may experience only mouth itching. However, if they accidentally eat a whole peanut, they may have a more severe reaction, including difficulty breathing and vomiting. In the case of medication allergy, if the medication is given directly into the bloodstream through an IV, the allergic reaction is more likely to be severe than if the medication is given by mouth.

Can a person have an anaphylactic response after the first exposure to an allergen?

Unfortunately, in food allergies, reactions can occur upon first exposure to the food. 

When are severe food allergies most commonly diagnosed?

Many food allergies are diagnosed in childhood; up to eight percent of children have food allergies. The most common food allergy before 4 years of age is milk allergy. Over 170 foods have been reported to cause food allergies, but more than 90 percent of food allergies are caused by milk, wheat, soy, egg, tree nuts, peanuts, shellfish, and fish. Shellfish and fish allergies can start in adulthood.

Should all children be tested for food allergies before any exposure has occurred?

Guidelines published by the National Institute of Allergy and Infectious Diseases (NIAID) state that only children with risk factors for food allergy should be tested before any exposure has occurred. Children who have moderate to severe atopic dermatitis or eczema (which appears as dry, itchy red skin) are more likely to have food allergies and should be tested. Also, if one child has food allergies, it is recommended that her siblings be tested for food allergies, too. If the parents have allergies themselves (whether it be seasonal allergies, atopic dermatitis, or food allergies), it is recommended to check the child for food allergies, too—food allergies have a genetic component.

Can anything prevent an anaphylactic response?

The safest thing to do—and the standard treatment for anaphylaxis—is strict avoidance of the allergen and carrying two epinephrine injectors with you or with your child at all times.

In the case of bee allergy, one of the things you can do to prevent being stung is to try not to look like a flower. Don’t wear a black shirt with yellow sleeves. Beware of bees inside straws or canned drinks—that can lead to stings on the tongue or throat. Keep food covered until eaten to prevent the bees from hovering over the food and potentially stinging you. Wear closed-toe shoes outdoors and avoid going barefoot. Also, avoid loose-fitting garments that can trap bees between the material and your skin.

If you have a food allergy, it’s very important you educate yourself on how to read food labels. Food labels are required to clearly identify if the food contains one of eight specific food allergy sources—milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, and soy. However, this rule does not apply to every food, and companies may change their recipes at any time. Also, the allergen can be hidden in the ingredient list. Therefore, it’s important you learn to read and understand food labels to protect against accidental exposure to an allergen.

Also, be very vigilant when going out to restaurants—bring a restaurant card with you and ask to speak with the chef or restaurant manager and let them know of your life-threatening allergies. (Restaurant cards can be found at

How is anaphylaxis treated?

The standard treatment for anaphylaxis is to give epinephrine and call 911. Epinephrine is a hormone that’s naturally produced by the body. When you have an anaphylactic reaction and receive an epinephrine injection, you are receiving the epinephrine in therapeutic amounts to help the body overcome the allergic reaction. It is a life-saving medicine. In the instances where I’ve had to give it to patients who were having anaphylaxis, it works within a minute to make them feel better. But because it’s a hormone naturally produced by the body, the body rapidly degrades epinephrine, too. If in 10 minutes the symptoms start to come back or the reaction is so severe that the first dose of epinephrine was not enough, you need to give the second dose of epinephrine. This is the reason why it is important to carry two doses of epinephrine with you at all times.

After injecting epinephrine, call 911. It is important to call 911 and be brought to the emergency room in case additional medications are needed to treat your anaphylactic episode. Also, up to 20 percent of allergic reactions can result in a secondary reaction that can be just as severe as the initial allergic reaction. It is important to be monitored in the emergency room or hospital for this secondary reaction.

Antihistamines such as diphenhydramine or cetirizine are considered a second-line treatment for anaphylaxis. They can help with itching and hives but they cannot reverse the most severe anaphylaxis responses—low blood pressure, difficulty breathing, abdominal pains, and vomiting.

How reliable is epinephrine if it has expired?

The bottom line is, even if it’s expired, use the epinephrine injection if you or your child is having an anaphylactic response. Studies show that even expired epinephrine has viable medicine that can effectively treat an allergic reaction.

When you pick up your epinephrine injectors from the pharmacy, make a note of the expiration date. Usually epinephrine is good for about a year, but it depends on the date it was manufactured. If you get one that is set to expire within a few months, ask your pharmacy for one that is not about to expire. If your epinephrine autoinjector has a clear window in it, check regularly that it has not become cloudy or filled with black particles. This signals that the epinephrine has degraded. If that happens, call your physician to get a refill on your epinephrine so you can get one that is 100 percent effective.

Which patients should always carry epinephrine?

Anybody who has been diagnosed with anaphylaxis for any reason—be it from food, medication, or insects—should be carrying two doses of epinephrine with them at all times. Anaphylaxis is a life-threatening condition, and epinephrine is the life-saving treatment for it. 

At what age can a child start carrying their own epinephrine injectors?

It depends on the emotional maturity of the child. We typically wait until a child is about 12 years old for them to carry the epinephrine with them at school in their backpacks. However, children vary in their maturity levels and when they feel comfortable carrying the epinephrine. The important thing is working with your allergist and your child to find out when they’re ready. It’s ideal for the child to be able to carry the epinephrine injector with them so if they have an allergic reaction, they can administer it immediately. The sooner your child can receive the epinephrine after an allergic reaction begins, the better off he is.