The Role of Epinephrine Auto-Injectors in Managing Severe Allergic Reactions
Managing severe allergic reactions, known as anaphylaxis, can be life-threatening and requires immediate administration of epinephrine. Epinephrine auto-injectors deliver a fast, life-saving dose of medication for individuals suffering an anaphylactic reaction.
What is Epinephrine (Adrenaline)? How Does it Work?
Epinephrine, or adrenaline, is a hormone and a neurotransmitter that partakes in the body’s fight-or-flight response or, in medical terms, acute stress response. When administered for severe allergic reactions, epinephrine constricts the blood vessels and increases blood pressure.
Epinephrine has been used as a medication to treat cardiac arrest, eye surgery, septic shock, asthma, and anaphylaxis. Adrenaline relaxes the muscles in the airways, reducing breathing difficulties or wheezing from anaphylaxis. Using an epinephrine auto-injector during an anaphylactic reaction can help reduce skin irritation from allergies, such as swelling or hives.
How to Administer Epinephrine for Severe Allergic Reactions
Epinephrine auto-injectors are relatively easy to use and designed for quick administration. Most auto-injectors have the steps listed on the device, but knowing how to use an epinephrine auto-injector before an emergency happens is essential. Here are a few steps on how to administer epinephrine:
- Remove the auto-injector from its case
- Remove the safety cap(s)
- Hold the auto-injector firmly with the needle end pointing down
- Place the injector against the outer thigh
- Press firmly and hold for 10 seconds
- Remove the auto-injector and massage the injection site
- Seek immediate medical attention
- Use a second dose if needed
When the needle deploys, it injects a life-saving dose of epinephrine into the muscle. Massaging the injection area helps disperse the medication. Even if anaphylaxis symptoms improve, always visit the emergency room following an allergic reaction. Going to the emergency room prevents the potential of biphasic anaphylaxis, which is a second onset of anaphylaxis without further allergen exposure.
The Use of Epinephrine Auto-Injectors for Anaphylaxis Treatment
Epinephrine is the first-line treatment for anaphylaxis from common allergens, including certain foods, latex, medications, and insect stings. Anaphylaxis is a potentially life-threatening allergic reaction followed by flushed skin, hives, swelling of the throat and tongue, itchiness, trouble breathing, and tightening of the throat.
Epinephrine auto-injectors, such as Epipens or Auvi-Q, are pre-filled devices that deliver a life-saving dose of epinephrine intramuscularly. The rapid absorption from the muscle into the bloodstream allows for immediate onset of action, which is crucial in an anaphylaxis emergency. Epinephrine is naturally produced by the adrenal glands and acts on several receptors to fight symptoms of anaphylaxis when injected.
Vasoconstriction
Administration of epinephrine (adrenaline) causes the narrowing of blood vessels, also known as vasoconstriction. Blood pressure drops during an anaphylactic reaction, and the injection of epinephrine helps to increase it. Epinephrine constricts the blood vessels, which counteracts the widening of blood vessels (vasodilation), which leads to anaphylactic shock.
Bronchodilation
One of the most dangerous symptoms of severe allergic reactions is the swelling and constriction of airways (bronchoconstriction). During an anaphylactic reaction, some individuals may experience tightening or swelling of the throat, which may block airways and cause breathing difficulties. Epinephrine auto-injection relaxes the muscles in the lungs and causes the air passages to widen, a process known as bronchodilation. Injecting a life-saving dose of epinephrine during anaphylaxis mitigates shortness of breath, wheezing, and respiratory distress.
Reduction of Swelling
Anaphylaxis causes symptoms of skin swelling, rashes, itching, and hives. Using an epinephrine auto-injector when experiencing an anaphylactic reaction stabilizes mast cells and basophils, reducing the swelling and hives. These cells release inflammatory mediators such as histamine during a severe allergic reaction. As epinephrine inhibits this release, it works to curb the severity of the allergic response and prevent it from progressing.
Increase in Cardiac Output
Cardiovascular symptoms of anaphylaxis include hypotension, anaphylactic shock, irregular heartbeat (cardiac arrhythmias), ventricular dysfunction, and cardiac arrest. The use of epinephrine intravenously (IV) has been used to treat patients in cardiac arrest.
Epinephrine temporarily increases cardiac output, heart rate, blood flow, and blood pressure during a severe allergic reaction. This mechanism of action helps the body maintain circulation and oxygen delivery to vital organs, counterbalancing rapid or weak pulse from anaphylaxis.
Understanding Severe Allergic Reactions: Triggers, Symptoms, and Epinephrine Treatment
Epinephrine auto-injectors typically come in two dosages, depending on the individual’s weight and age. Common auto-injectors typically contain 0.3 mg of epinephrine for adults and 0.15mg for children or individuals under 66 lbs. When someone is experiencing an anaphylactic reaction, time is of the essence. The sooner the epinephrine is auto-injected, the more effective it will be in curbing symptoms of anaphylaxis.
It is recommended that the epinephrine auto-injector is used at the first sign of a severe allergic reaction. After administering the epinephrine injection, seek emergency medical attention immediately.
Common Allergens and Anaphylaxis Triggers
Epinephrine is the only first-response treatment for severe allergic reactions from common allergens, including:
- Food allergies: peanuts, tree nuts, fish, shellfish, milk, eggs, wheat, soy, and sesame
- Insect stings or bites: bees, wasps, yellow jackets, hornets, and fire ants
- Latex allergies
- Medication allergies: certain antibiotics, aspirin, insulin, and other pain relievers
The common triggers for anaphylaxis, including food allergens, insect stings, latex products, and certain medications, can lead to life-threatening consequences when exposed.
The Signs and Symptoms of a Severe Allergic Reaction
Recognizing the signs and symptoms of anaphylaxis is critical for taking immediate action and using an epinephrine auto-injector. Anaphylaxis symptoms can include:
- Trouble breathing or wheezing
- Skin swelling
- Rapid or weak pulse
- Low blood pressure (hypotension)
- Tightening of the throat
- Swelling of the tongue, lips, or throat
- Flushed or pale skin
- Skin rash or hives
- Nausea, vomiting, or diarrhea
- Dizziness and/or fainting
If you’ve been exposed to an allergen and are experiencing any side effects of anaphylaxis, seek medical attention immediately. Anaphylaxis can progress quickly, highlighting the significance of always carrying epinephrine auto-injectors.
Best Practices for Epinephrine Auto-Injectors
Individuals with severe allergies at risk of anaphylaxis should always carry TWO epinephrine auto-injectors. Inform family members, friends, caregivers, and coworkers of your allergies and show them how to use an epinephrine injector. Regularly check your epinephrine injectors to make sure they have not expired. Replace your epinephrine injector if it has expired or is about to expire. Epinephrine auto-injectors often come with a tester device to practice with and ensure you’re prepared in an emergency.
References:
- Cleveland Clinic, 2022. Epinephrine (Adrenaline).
- John Hopkins Medicine. Anaphylaxis.
- Cleveland Clinic. Epinephrine Auto-Injector.
- Allergy & Asthma Network. What is Epinephrine?
- Harvard Health Publishing, 2020. Epinephrine is the only effective treatment for anaphylaxis.
- Asthma and Allergy Foundation of America, 2017. Anaphylaxis (Severe Allergic Reaction).
- National Cancer Institute. Drug Dictionary: mast cell stabilizer TF002.
- Clinical & Experimental Immunology, 2008. Allergy and the cardiovascular system.
