Patient information: Use of an epinephrine autoinjector

INTRODUCTION

Allergic reactions can be triggered by foods, medications, exercise, latex, insect stings, or unknown triggers, and can cause a sudden, potentially life-threatening allergic reaction called anaphylaxis. Epinephrine (also known as adrenaline) is a medicine that treats the symptoms of serious allergic reactions. (See "Patient information: Anaphylaxis symptoms and diagnosis".)

PATIENT AND FAMILY EDUCATION

A person with allergies, as well as his or her family, close friends, teachers, and co-workers, should learn to use an epinephrine autoinjector before it is needed. Anaphylaxis is unpredictable, and while a person may have a mild reaction one time, a serious or even life-threatening reaction can occur the next time. A person suffering with anaphylaxis may panic and be unable to assist with their own injection. In addition, a quick response is necessary to prevent serious complications of anaphylaxis.

An epinephrine autoinjector prescription should be filled immediately. Anyone who is at risk of anaphylaxis should keep at least one epinephrine autoinjector with them at all times. Most allergy specialists recommend having at least two doses of epinephrine available, and some prescribe more. The reason for this is that two doses of epinephrine may be needed to treat a more severe anaphylactic reaction.

After filling the prescription, patients/caregivers should practice using the autoinjector. Many manufacturers include a practice injector (that does not have a needle or actual medicine). A video (on the internet or DVD) showing how the autoinjector is used is available from manufacturers and should be reviewed periodically.

The autoinjector should always be available, including at school or work, when attending parties or traveling, during exercise, and while dining out. It should be kept in a place that can be easily located by others in an emergency and family and friends should be informed about where the injector is stored. It is also important to ensure that the injector is not expired, although an expired injector may be used if there is no alternative.

Epinephrine should be stored at normal room temperature, away from extreme cold and heat (eg, a car's glove compartment). The epinephrine cartridge window should be examined periodically to ensure that the solution is colorless and contains no floating particles. Solutions that are discolored or contain particles should be replaced. Autoinjectors that have expired should be replaced even if the solution still looks clear.

SYMPTOMS OF ALLERGY

Allergic reaction can produce symptoms throughout the body. The symptoms of anaphylaxis are discussed in detail in a separate topic. (See "Patient information: Anaphylaxis symptoms and diagnosis".)

EPINEPHRINE IS THE BEST TREATMENT FOR ANAPHYLAXIS

Epinephrine is the best treatment for anaphylaxis and it works best if it is given within the first few minutes of a severe allergic reaction. Epinephrine rapidly treats all of the most dangerous symptoms of anaphylaxis - including throat swelling, difficulty breathing, and low blood pressure. However, epinephrine is not a perfect treatment so allergic triggers should be avoided.

Other medicines that are used in the treatment of allergic reactions can help with some of the symptoms, but only epinephrine treats the entire reaction. Antihistamines (such as diphenhydramine and others) help with itching and hives, and asthma inhalers (such as albuterol) can help with coughing and wheezing, but these medications do not treat the dangerous symptoms of throat swelling and low blood pressure. In addition, antihistamines taken by mouth are too slow-acting to be effective in a rapidly-developing episode of anaphylaxis. In contrast, injected epinephrine works within a few minutes.

Therefore, antihistamines and asthma inhalers are useful in the treatment of anaphylaxis, but they are NOT substitutes for epinephrine. There is no substitute for epinephrine in anaphylaxis.

WHEN TO USE AN EPINEPHRINE AUTOINJECTOR

A person who is having an allergic reaction should use their epinephrine autoinjector immediately if they:

• Are having trouble breathing
• Feel tightness in the throat
• Feel lightheaded or think they might pass out

If treating a child with an allergic reaction, also use the autoinjector if the child:

• Is not responding, seems groggy, or passes out during an allergic reaction
• Has food allergies and is vomiting repeatedly shortly after eating, especially if these symptoms are accompanied by flushing or hives
• Is coughing repeatedly during an allergic reaction
• Had previous anaphylaxis and develops widespread hives after possibly eating a trigger food
• Has definitely eaten a trigger food that previously caused very severe anaphylaxis. In this case, use the autoinjector before symptoms appear.

HOW TO USE AN EPINEPHRINE AUTOINJECTOR

The patient and a family member should review instructions provided with the autoinjector each time a refill is obtained in case there are changes. Instructions may differ from one autoinjector to another.

Epipen® or Epipen Jr.® — These epinephrine auto-injectors contain one dose per injector (picture 1). They are available in two different doses, one intended for older children and adults, and the other for use in young children.

Stay with other people if possible. There is no need to undress, because the injector works through clothing. However, when possible, lift the edge of a skirt or lower pants to avoid hitting a buckle, zipper, or contents of the pockets.

  1. Unscrew the cap and remove the pen from its case.

  2. Hold the injector in your dominant hand, making a fist. Keep fingers away from both ends to avoid sticking them. The black end contains the needle and should be facing down. Use your other hand to pull off the gray safety-release cap.

  3. Press the black tip firmly into the upper, outer thigh muscle and hold in place for 10 seconds to allow all the medicine to be injected (figure 1). The cartridge window will show red.

  4. Remove the pen. The cartridge window will show red and the needle should be visible; this means that the medication was given.

  5. Massage the injected area for 10 seconds.

  6. Call 911 and get to the nearest emergency department immediately (patients should not drive themselves). Allergic reactions sometimes come back.

  7. Replace the pen in the case, needle end first, and take it to the hospital so that the needle can be disposed of safely.

The Epipen® is available in packages of two, in case a second dose is needed. Large-sized adults may need to repeat the dose. A second dose may also be needed if symptoms are not improving or getting worse after about five minutes, or if symptoms come back before reaching the emergency department.

Twinject® — This auto-injector contains two doses in one device (picture 2). It is available in two different strengths, one intended for use in children and the other, for use in adolescents and adults.

Stay with other people if possible. There is no need to undress, because the injector works through clothing. However, when possible, lift the edge of a skirt or lower pants to avoid hitting a buckle, zipper, or contents of the pockets.

  1. Remove the injector from its blue case.

  2. Pull off the green cap, labeled "1". This will reveal a red tip, which contains a needle inside. Do not place your finger or hand over the red tip.

  3. Pull off the green cap, labeled "2".

  4. Form a fist around the autoinjector with the red tip pointing down.

  5. Place the red tip against the upper, outer thigh, and press firmly until the needle enters the skin (figure 1). Hold in place for 10 seconds to allow all the medicine to be injected.

  6. Remove the injector and check the red cap. If the needle is visible, epinephrine was given. If the needle is not present, repeat steps 4 through 5 again.

  7. Massage the injected area for 10 seconds.

  8. Call 911 and get to the nearest emergency department immediately (Patients should not drive themselves). Allergic reactions sometimes come back.

The Twinject® contains a second dose inside the cartridge. A second dose may be needed if symptoms are not improving or getting worse after about five minutes, or if symptoms come back before reaching the emergency department. Studies have shown that one in three patients will need a second dose.

In case a second dose is needed, remove the inside injector:

• Unscrew and remove the red cap, taking care to avoid the needle.
• Pull the blue syringe out of the barrel.
• Slide the yellow collar off the plunger. Do not pull up on the plunger.

To use the second dose:

• Press the injector firmly into your thigh muscle; push the plunger all the way down to inject the medicine.
• Remove the injector.
• Place the used syringe and needle back into the case and take it to the hospital.

If the second dose was not needed, the syringe/needle can be stored in the blue case for disposal at the hospital. The second dose CANNOT be saved for use another day.

Immediately after using the autoinjector — After using an autoinjector, it is important to immediately seek care in an emergency department. The reaction may initially improve but then come back. When possible, ask someone else to call for help. If alone, treat with the autoinjector first and then call or walk for help.

If the person experiencing anaphylaxis begins to feel weak or dizzy, have them lie down and elevate the knees or feet. If they feel faint or have fainted, leave them in the lying down position. NEVER prop them up because this can prevent blood from reaching the heart and brain.

Side effects of epinephrine — The benefits of epinephrine are FAR GREATER than the risk of side effects. However, epinephrine can cause short-lived side effects in some patients. The most common side effects include the following:

• Heart — Fast and/or pounding heartbeat, fleeting chest pain
• Nervous system — Nervousness, trembling, feeling cold, anxiety, headache, dizziness
• Digestive system — Nausea, dry throat
• Lungs — Fleeting shortness of breath

Injector disposal — Injectors should not be thrown away with household trash since they contain a needle. Patients should take their used injector (inside the case) to a hospital or healthcare provider for proper disposal.

FOLLOW-UP CARE

People have varying responses to a severe allergic reaction. Some people have symptoms that will resolve rapidly and completely with treatment. These people may feel tired but otherwise normal afterwards. Other people have symptoms that take longer to resolve. For most people, facial swelling and asthma symptoms resolve completely after 24 to 48 hours.

Some people experience a second reaction after the initial allergic reaction, although this is not common. Second reactions can occur hours to days later, although most second reactions happen within eight hours. For this reason, it is important to stay at the emergency department for a several hours of observation after a reaction.

A healthcare provider may prescribe additional medications for treatment after a reaction, such as antihistamines or oral glucocorticoids (eg, prednisone). It is possible (but not proven) that these medications can help to prevent a second reaction.

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two people are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.

This discussion will be updated as needed every four months on our web site (www.uptodate.com/patients). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.

Some of the most pertinent include:

Patient Level Information:
Patient information: Anaphylaxis symptoms and diagnosis

Professional Level Information:
Anaphylaxis: Rapid recognition and treatment
Clinical manifestations and pathogenesis of hereditary angioedema
Clinical manifestations of food allergy: An overview
Diagnosis of Hymenoptera venom allergy
Diagnostic tools for food allergy
Drug eruptions
Fatal anaphylaxis
Food allergy in schools and camps
Food-induced anaphylaxis
History and physical examination in the patient with possible food allergy
Laboratory tests to support the clinical diagnosis of anaphylaxis
Pathophysiology of anaphylaxis
Prescribing epinephrine for anaphylaxis self-treatment
Stings of Hymenoptera insects: Reaction types and acute management
Treatment of acute attacks in hereditary and acquired angioedema
Unique aspects of anaphylaxis in infants

A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable.

• The Food Allergy and Anaphylaxis Network

      (www.foodallergy.org)

• American Academy of Allergy, Asthma, and Immunology

      (www.aaaai.org)

• Anaphylaxis Foundation and Anaphylaxis Network of Canada

      (www.anaphylaxis.org)

• The Anaphylaxis Campaign

      (www.anaphylaxis.org.uk)

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