Anaphylaxis

Anaphylaxis is a severe allergic reaction involving the whole body. It’s important to know about because it can happen quickly and be very dangerous — even fatal. 

Like with an allergy, anaphylaxis is a case of mistaken identity. It starts when your immune system mistakes a harmless substance (like a food) for a foreign or harmful invader. The body goes into overdrive and puts up an overblown immune defense to the perceived invader. The cells of the immune system release large amounts of inflammatory chemicals, like histamines. Within minutes, you can start to see symptoms. 

Anaphylaxis has a rather unpredictable nature. It can happen even if you’ve never reacted to something before, and someone who has had mild reactions to a substance can go on to have a more severe reaction the next time.

Anaphylaxis is most common in people who are allergic to: 

• Peanuts
• Tree nuts
• Bee stings
• Certain medications 

It’s also more likely if you’ve had it before.

It’s not clear exactly why some people get anaphylaxis and others don’t. Allergies and anaphylaxis have a tendency to run in families, but genetics aren’t the whole picture. 

Anaphylaxis is more likely in people who also have allergies and asthma. If you’ve had severe allergic reactions in the past, then you are at higher risk for anaphylaxis. 

According to the American College of Allergy, Asthma, and Immunology, the most common causes of anaphylaxis are:

• Foods
• Insect stings
• Medications
• Latex 

When these otherwise harmless substances cause an allergic reaction, they are called “allergens”.

Examples of allergens include:

• Food: peanuts, tree nuts (walnuts, almonds, pecans), fish, shellfish, cow’s milk, eggs
• Latex: found in disposable gloves, intravenous tubes, syringes, adhesive tapes, catheters
• Insect stings: from bees, wasps, hornets, yellow jackets, fire ants 
• Medications: penicillin, aspirin, muscle relaxants, anesthesia
• Contrast dye: sometimes used for medical imaging

To complicate matters, anaphylaxis can be triggered by substances that aren’t allergens, such as exercise, cold, or heat. And sometimes, the cause of anaphylaxis is never pinned down (this is called idiopathic anaphylaxis).

The symptoms of anaphylaxis come on quickly, usually within minutes of contact with a trigger. 

When someone has an anaphylactic reaction, it can start out with a rash or a feeling like something “just isn’t right.” But it can progress quickly into the following: 

• Difficulty breathing
• Hives and itching
• Runny nose
• Fast heartbeat
• Tightness of the throat
• Nausea or abdominal pain 
• Diarrhea
• Dizziness or lightheadedness
• Feeling of doom
• Confusion and anxiety

Skin symptoms (such as hives, itching, and/or swelling) are usually the first to show up — but not always. Other symptoms, such as a runny nose or vomiting, may follow as the reaction gets worse. It might not be obvious what is going on, especially if the person has never had anaphylaxis before. 

The most severe cases affect the respiratory and cardiovascular systems: The airways start to close, blood pressure starts to drop, and the heart must then work harder. This is a dangerous, life-threatening situation called anaphylactic shock.

Symptoms of anaphylaxis can be milder, but it’s difficult to predict whether or how quickly they will get worse. It’s possible for symptoms to be delayed for several hours. It’s also possible to have another reaction hours after the first one ends.

Anaphylaxis is usually diagnosed in an emergency setting. The diagnosis is based on signs and symptoms, not one particular test. 

Blood tests can look for the presence of some inflammatory chemicals called tryptase and histamine, which may be elevated during anaphylaxis. But these are not required for diagnosis. 

If you have known allergies, it may help to see an allergist. Allergists are doctors who specialize in allergies, asthma, and other immune system problems. They can help you identify your trigger(s), maybe run some tests, and talk with you about treatment options and your risk of anaphylaxis.

It’s important to know that allergy test results do not predict the severity of future reactions. In other words, anyone is at risk for anaphylaxis, regardless of what the tests show.

Medications

Anaphylaxis is always a medical emergency. If it’s not treated quickly, it can be life threatening. 

Epinephrine is a medication that helps stop a life-threatening allergic reaction. It comes in an injectable device (called an auto-injector), which can be used quickly when severe allergy occurs. An auto-injector can be used only once.

People with severe allergies should carry their epinephrine auto-injectors on them at all times and know how to use them. 

Epinephrine devices are only available by prescription:

• EpiPen
• EpiPen Jr
• Adrenaclick
• Symjepi
• Auvi-Q

Here’s what to do if you see someone experiencing anaphylaxis:

• Administer epinephrine: Give epinephrine as soon as possible if an auto-injector is available. 
• Call 911: Or get them to the nearest emergency room. 
• Have them lie down flat: Sitting is OK if it helps their breathing, but do it slowly — avoid sudden standing or sitting.
• Make sure they get a medical evaluation: Do this even if they start to feel better. There is a risk of symptoms getting worse or another reaction happening minutes to hours later. 

Someone who has had an anaphylactic attack always needs to go to the hospital afterward — even if they are feeling better. They are likely to need more epinephrine once the first shot wears off, as well as other life-saving medications.

Prevention

Unfortunately, if you’ve had an anaphylactic reaction, you’re likely to have another — and it could be more severe next time. 

The best way to prevent another anaphylactic reaction is to avoid the trigger. For example, if you have a food allergy, always read menus and labels. It’s important to not only know what your trigger is, but also to be able to recognize the signs and symptoms of anaphylaxis. That way, you can feel it coming on and know what to do. 

Also consider wearing a bracelet and carrying a wallet card that clearly states what your allergy is. These items let bystanders or healthcare workers know about your allergy if you’re not able to speak for yourself.

If you have an epinephrine auto-injector:

• Be sure you know how to use it. 
• Keep it up to date (replace it if it expires).
• Keep it with you at all times. 
• Make sure your friends and family know about your allergy. 
• Make sure your friends and family know about your auto-injector, where you keep it, and how to use it (in case they need to give you the medication).

If you don’t have an epinephrine auto-injector, and you think you might need one, contact your healthcare provider right away. Epinephrine is safe, effective, and life-saving.