What's the mechanism of action for epinephrine?

Epinephrine (for example: EpiPen) is classified as a sympathomimetic agent and works by activating both alpha and beta receptors found in your body in response to a severe allergy (called anaphylaxis). By acting on alpha receptors, it constricts your blood vessels to help maintain your blood pressure and heart function. Through its action on beta receptors, it relaxes the smooth muscle in the airways of your lungs to help relieve shortness of breath and wheezing.

Epinephrine may also relax smooth muscles of the stomach, intestine, uterus and urinary bladder to relieve symptoms in your digestive or urinary tracts.

In a severe allergy, epinephrine works quickly by:

• relaxing your airway muscles to help with breathing
• constricts your blood vessels to maintain your blood pressure
• reduces swelling, hives or itching that may occur around your face, eyes or lips
• stimulates the heart (increases heart rate)
• prevent the release of histamine, which can further worsen allergies.

If you, or someone else, has used epinephrine injection (for example: EpiPen) in an emergency situation, you should call 911 or other emergency services right away for medical care.

How do I recognize anaphylaxis?

A severe allergy, called anaphylaxis (pronounced "ana-fi-LAX-is"), is life-threatening and a medical emergency. Anaphylaxis is the most severe of all allergies, usually occurs in minutes (but can be delayed for hours), and may be deadly if not promptly treated.

In a severe allergic reaction, your throat may swell, you may have trouble breathing, you may develop hives, swelling or redness, and your blood pressure can drop.

Anaphylaxis can occur with a wide variety of products, such as:

• Food: eggs, shellfish and other seafood, tree nuts (such as walnut, cashew, Brazil nut), grains, mil
• Medicine: including other penicillin-type drugs called cephalosporins; "sulfa" antibiotics like Bactrim, NSAIDs, or lidocaine
• Insects: Wasps like yellow jackets, paper wasps, and hornets; fire ants; bees
• Certain X-ray contrast dyes (iodine, barium) and industrial/household chemicals
• Latex rubber
• Allergy shots
• Exercise-induced anaphylaxis

A mild allergy such as hay fever is the result of a release of histamine that can lead to a runny nose, watery eyes, or mild rash. However, with anaphylaxis, immune chemicals can lead to a more severe reaction that affects the whole body, such as:

• Hives and swelling
• Wheezing
• Severe breathing or swallowing problems due to throat swelling
• Drop in blood pressure (hypotension), fainting
• Chest tightness
• Nausea, vomiting, stomach cramps
• Pale or red color to skin

Related questions

• Can you use an expired EpiPen in an emergency?
• Norepinephrine vs epinephrine: what's the difference?
• Can you bring an EpiPen on a plane?

What can I do to prevent severe allergies?

People with a history of anaphylaxis should carry epinephrine such as the EpiPen or the generic, authorized generics, or other branded versions with them at all times. Today there are many options available for epinephrine auto-injectors.

Talk to your healthcare provider about developing an Anaphylaxis Action Plan that you can utilize day-in and day-out. Think about places and times away from home where you might be at bigger risk for exposure to allergens -- such as at restaurants, school, work, sporting events, summer camp, or on planes. Be sure to have epinephrine available in these places.

Work with your child's school nurse to determine their policies, and teach and regularly review how to use the epinephrine auto-injector for emergencies.

Epinephrine products include:

• EpiPen
• EpiPen 2-Pak
• Adrenaclick
• Symjepi
• Auvi-Q
• generics

Always have two doses of an epinephrine auto-injector on-hand. A second dose may be needed in cases of a prolonged allergic reaction. If you have life-threatening allergies, you should wear a medical alert identification necklace or bracelet to alert first-responders to your severe allergy. Be sure to replace your epinephrine injector before it expires.

This is not all the information you need to know about epinephrine for safe and effective use and does not take the place of your doctor’s directions. Review the full product information and discuss this information and any questions you have with your doctor or other health care provider.