What Is Anaphylactic Shock? Symptoms, Causes, and Treatments

Anaphylactic Shock: A Life-Threatening Allergic Reaction

Anaphylactic shock is a severe allergic reaction that is potentially life-threatening. It can happen within minutes of exposure to an allergen (something you are allergic to, such as an insect sting or certain foods). Anaphylaxis is a medical emergency and can be fatal without treatment with epinephrine.

What Happens To The Body During Anaphylaxis?

Anaphylaxis is a serious reaction that occurs when the body’s immune system overreacts and mistakenly identifies a harmless substance as dangerous. In response, the immune system releases a flood of chemicals that cause the body to go into shock. These chemicals cause allergy symptoms such as skin reactions, throat swelling, and difficulty breathing.

Pathophysiology: Anaphylaxis Impact on Different Body Systems

Anaphylactic reactions cause severe allergy symptoms in multiple systems and vital organs, including: 

• The circulatory system, causing a dangerous drop in blood pressure and a rapid, weak pulse

• The respiratory system, causing narrowing of the airways, making breathing difficult

• The ear, nose, and throat (ENT) system, causing nasal congestion, tongue swelling, a hoarse voice, throat tightening, wheezing, and trouble breathing.

• The dermatologic system, causing skin reactions such as severe skin rash, hives, and itching

• The digestive system, causing gastrointestinal symptoms such as abdominal pain, nausea, vomiting, and diarrhea

Importance of Immediate Attention

If an anaphylactic reaction is not treated with an injection of epinephrine, it can be fatal. That’s why it is important to recognize the symptoms of severe anaphylaxis, call 911 for emergency medical help, and give the person an injection of epinephrine if it is available. If you are not familiar with epinephrine injections, immediately get the attention of a healthcare professional in emergency situations. You can learn more on how to administer epinephrine with Epipen directions. If you, your child, or another family member experience anaphylactic reactions, it is recommended to become very comfortable with epinephrine and be confident with the administration.

Risk Factors 

People who have had a severe allergic reaction in the past are at risk of having another one. Even if the first one was a mild allergic reaction, future reactions can cause severe symptoms and be life-threatening. Medications are common causes of allergic reactions. Even medication you have been taking for years can suddenly cause an anaphylactic reaction.

Other risk factors include a history of asthma, heart disease, and mastocytosis (a condition in which there is an abnormal accumulation of white blood cells). Latex-induced anaphylactic reactions can occur in healthcare workers, people who handle natural latex, and children with spina bifida and genitourinary abnormalities.

If you are at risk of severe allergy symptoms, it is important to carry an auto-injector epinephrine injection (EpiPen). 

Symptoms of Anaphylactic Shock

Early Signs and Symptoms of Anaphylaxis

Signs and symptoms of an anaphylactic reaction typically develop within minutes. However, a delayed anaphylactic reaction can happen anywhere from half an hour to 4 hours after exposure to an allergen. 

Early symptoms can be nonspecific sensations, often described as “feeling strange” or a “feeling of doom.” These symptoms can quickly progress to more serious anaphylaxis symptoms.

Progressive Symptoms of a Severe Allergic Reaction

The above symptoms can rapidly progress to symptoms of severe anaphylaxis, including:

• Pale or flushed skin

• Skin rash, hives, itching

• Low blood pressure

• Weak, fast pulse

• Nasal congestion 

• Swelling of the tongue

• Laryngeal edema (swelling of the throat)

• Tightness in the throat

• Wheezing

• Hoarse voice

• Chest pain or tightness

• Difficulty breathing

• Stomach pain

• Nausea

• Vomiting

• Diarrhea

• Dizziness

• Fainting 

Critical Indicators

Low blood pressure, a fast and weak pulse, tongue and throat swelling, and difficulty breathing are the critical indicators of serious allergic reactions that require emergency medical treatment. 

Triggers and Causes

What Are The Triggers of Anaphylactic Shock? 

Common allergens that can trigger anaphylaxis include:

• Food allergies (for example, peanuts, walnuts, pecans, other tree nuts, shellfish, fish, seafood, eggs, cow’s milk)

• Stinging insects and insect venom (for example, bee stings, wasps, yellow jackets, hornets, fire ants, and Lone Star ticks)

• Latex (found in medical equipment and supplies such as disposable gloves, syringes, catheters, adhesive tapes, and intravenous tubes)

• Certain medications (for example, anesthesia drugs, IV contrast used during imaging studies, certain antibiotics such as penicillin, aspirin, and nonsteroidal anti-inflammatory drugs such as ibuprofen)

Less Common Triggers

• Exercise-induced anaphylaxis can occur after aerobic exercise such as walking or jogging. This may or may not be associated with a food trigger or other allergens such as hot, cold or humid weather, pollen, or medication. 

• Coital anaphylaxis in females occurs during or after sexual intercourse with a man. Researchers believe it is from exposure to allergens transferred through semen, for example, something the man ate or a medication he took.

• Catamenial anaphylaxis occurs in association with menstruation in females.

• Idiopathic anaphylaxis is when the symptoms of anaphylaxis occur without any obvious trigger, and the cause remains unknown.

Treatment for Anaphylactic Shock

Can Anaphylaxis Go Away On Its Own?

Sometimes, even severe cases of allergic reactions can go away on their own without treatment. However, delaying treatment can be potentially fatal and is not recommended. Rather than waiting to see what happens, you should treat anaphylaxis with epinephrine and seek prompt treatment in the nearest emergency room.

Immediate Actions to Take: What To Do If Someone Goes Into Anaphylactic Shock?

Here are the steps to take if someone goes into anaphylactic shock (pale, cool, clammy skin; weak, rapid pulse; breathing difficulties; confusion; or loss of consciousness):

1. Call 911 for emergency medical help.

2. Use an epinephrine auto-injector, if one is available, for immediate treatment.

3. Place the person in a lying position with the legs elevated.

4. Check the person's pulse and breathing and administer cardiopulmonary resuscitation (CPR) if they have stopped breathing or their heart has stopped (cardiac arrest).

Administering Epinephrine: How Do You Treat An Anaphylactic Reaction?

People with a history of previous severe allergic reactions or anaphylaxis often carry an epinephrine autoinjector to quickly treat symptoms and prevent life-threatening respiratory and cardiovascular complications. This device has a needle and syringe containing the epinephrine medicine. It delivers a single dose of epinephrine when you press it into the thigh. 

Note: It is important to go to the nearest emergency room even after using epinephrine from an emergency kit. Epinephrine works quickly within 5-10 minutes, but its effects start wearing off in 20-30 minutes. Also, some people develop biphasic anaphylaxis, which is a recurrence of anaphylaxis symptoms or a second reaction after appropriate treatment, even without further exposure to the allergen.

How Do Doctors Treat Anaphylaxis in the Emergency Room?

The following measures may be used by emergency room physicians for treating anaphylaxis:

• Cardiopulmonary resuscitation (CPR) if someone has stopped breathing or their heart has stopped beating.

• Epinephrine to control the allergic response.

• Oxygen and breathing support.

• Intravenous antihistamine and corticosteroid drugs to reduce inflammation in the airway and ease breathing.

• Beta-agonists such as albuterol to improve breathing.

Follow-Up Care and Observation

Depending on the allergen that triggered an anaphylactic reaction, an allergy specialist or specialist in clinical immunology may recommend immunotherapy. This treatment consists of a series of allergy shots to desensitize the body to the allergen and reduce the allergic response to prevent severe allergic reactions in the future. 

You can also lower the risk of anaphylaxis in the future by avoiding known triggers and carrying an allergy medication, for example, an epinephrine injection auto-injector device, on you at all times. 

Note: A healthcare provider can make an anaphylaxis diagnosis based on history, blood tests (for example, tryptase enzyme, which is elevated for several hours after an anaphylaxis reaction), and skin tests. They can also rule out differential diagnoses, such as anaphylactoid reactions that mimic anaphylaxis but are not caused by an immune response.

Prevention and Management of Anaphylactic Shock

Identify and Avoid Triggers

The best way to prevent anaphylaxis is to avoid known allergens (substances that have caused a life-threatening allergic reaction in the past). 

Long-Term Management Strategies

If you have a history of anaphylaxis, you should: 

• Wear a medical alert necklace or bracelet that tells people about potentially life-threatening allergies to specific substances.

• Carry an emergency kit with an epinephrine autoinjector and/or other prescribed allergy medication with you at all times. Check the expiration date on the EpiPen periodically, as it may not work well if the medicine is past its expiry date. 

• Tell all your healthcare providers about medications that have caused drug-induced anaphylaxis in the past.

• If you have a history of experiencing severe anaphylaxis related to insect stings, take precautions to avoid insect bites. 

  • Wear long-sleeved shirts and pants when outdoors; 

  • Avoid walking barefoot on grass; 

  • Avoid wearing bright colors and perfumes or scented skincare products; 

  • Avoid drinking from open soda cans when outdoors; 

  • Move away from a stinging insect calmly without aggravating it by hitting or slapping it. 

• If you have a history of food-induced anaphylaxis in the past:

  • Read food labels carefully because exposure to even small amounts of food allergens can trigger a serious reaction;

  • Check the labels of commonly consumed foods from time to time as manufacturing processes and ingredients may change;

  • Tell servers in restaurants about your food allergy and ask how a dish is prepared. 

Emergency Preparedness Plans

Despite taking precautions, you can sometimes develop anaphylaxis after exposure to allergens. If this happens, you can respond quickly and effectively to this medical emergency by recognizing the signs and symptoms of anaphylaxis and treating them without delay. Make sure you replace your epinephrine autoinjector before its expiration date to ensure it works properly in case you have a severe reaction. Also, ensure you and people close to you know how and when to use the EpiPen device.