A recent study by Nationwide Children's Hospital in Columbus, Ohio, looked at the patient records from more than 400 pediatric and young adult patients who had experienced anaphylaxis, an acute allergic reaction to an antigen to which the body has become hypersensitive. The study found that parents, teachers and caregivers often failed to administer epinephrine, typically in the form of an auto-injector, even in children who had had similar episodes in the past.
The study is concerning, as many of my patients have a risk of anaphylaxis and injectable epinephrine is prescribed as an immediate remedy which can help reverse the symptoms of a life-threatening allergic reaction.
We prescribe an epinephrine auto-injector with the expectation that it will be used when someone has symptoms consistent with anaphylaxis because it’s the only thing that works. Taking an antihistamine, will not stop anaphylaxis, which is a systemic allergic reaction.
There may be a number of reasons why people are hesitant to use an EpiPen during an allergic reaction. Many people are afraid to stick themselves or family member with a needle. Sometimes people don’t react well in an emergency and may feel more comfortable having someone else take charge such as a first responder or an emergency room physician.
Most of the epinephrine auto-injectors are spring loaded. The needle is not visible until it is used. Epinephrine for treatment of anaphylaxis should be injected in the lateral or outside part of the thigh, into the large muscle there which helps the medication gain access to the bloodstream faster. From there, it travels back to the heart and is pumped all over the body where you need it. If it’s injected into fatty tissue, it’ll take longer to get there and won’t work as well. Delays in treatment and incorrect administration can result in poor outcomes.
Once you have used the auto-injector on one thigh, if the allergic reaction doesn’t subside or if a relapse occurs, use another EpiPen on the other thigh. This is why EpiPens are typically prescribed in pairs. It’s important to keep them together and within easy reach and not have one in the house and one in the car.
We recommend that patients use the second shot if they don’t feel better four minutes after an injection of epinephrine. If they do feel better but have another reaction later on, they should also use the second shot.
After administering the epinephrine, give the recommended dose of antihistamine and seek immediate medical attention. Histamine is the substance that causes an allergic reaction so taking an antihistamine helps block histamine receptors. Epinephrine will help stabilize mast cells, the source of histamine. Epinephrine also stabilizes blood vessels and other target organs so more blood flows from vein to the heart then into the arteries. It also increases heart rate and blood pressure so you get blood to the brain and other organs in order to prevent the person from going into shock.
In about a third of cases, the person can have a second reaction, so they should be observed by a medical professional. The study found that those who had received the epinephrine shot prior to seeking care were more likely to be treated and released from the Emergency Room versus those who had not.
Epinephrine causes a rapid heart rate which might cause some concern in adults because of the risk of undiagnosed heart disease. However, anaphylaxis itself is bad for the heart, so the benefit of using epinephrine far outweighs the risk.
The presence of heart disease is much lower in children so there is very little downside to giving epinephrine if a young person is having an allergic reaction. Most young people can withstand the minimal stress on their heart which can occur and the effects will wear off quickly so don’t be afraid to use an epinephrine auto-injector.
The most important thing is that in all severe allergic reactions people know what to do and use the auto-injector as recommended.