Epinephrine: When and How to Administer It

November 21, 2019
Epinephrine, or adrenaline, is a drug administered in different ways, depending on the patient's symptoms and situation. Epinephrine is useful mainly for the treatment of cardiac arrest and anaphylactic reactions.

Epinephrine, better known as adrenaline, is a hormone and neurotransmitter used in emergencies when the patient is suffering from cardiac arrest. This drug has historically been used to treat bronchospasms and hypoglycemia. However, today there are other more specific drugs in existence to treat these conditions.

Adrenaline is a substance that increases heart rate, constricts blood vessels, dilates the airways, and participates in the fight or flight reaction of the nervous system in an emergency. To get a little more technical, adrenaline is a catecholamine. It’s a monoamine synthesized in the adrenal glands and the precursors of this substance are phenylalanine and tyrosine.

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How is epinephrine administered?

Chemical structure of adrenaline or epinephrine

Epinephrine is prepared as part of an injectable solution. Also, different types of injections can administer this medication, as needed:

  • Intramuscular (IM)
  • Subcutaneous
  • Intravenous (IV)
  • Intracardiac: only in cases of extreme severity, and if the intravenous route is not practicable.

The last two types of administration must be carried out in the hospital, under cardiac monitoring. Additionally, the epinephrine solution must be diluted with one of the following substances before injection:

  • 0.9% sodium chloride solution
  • 5% glucose
  • 5% glucose in 0.9% sodium chloride solution.

Also, to prevent the drug from becoming inactive due to light or oxidation, it is a good idea to use the product right after diluting it.

Regarding the dosage and the method of administration, both parameters will depend on the diagnosis and the condition of the patient. However, in an emergency, the fastest method of administration is necessary (for example, via IV or an intravenous solution).

Uses of epinephrine

Adrenaline or epinephrine injection
As you can see, epinephrine is a solution available in a variety of different concentrations. The following conditions are some of the most frequent medical applications of epinephrine:

Heart attack

In addition to cardiac arrest, adrenaline is also useful for treating other heart problems, such as arrhythmias that result from a decreased or absent cardiac output.

The purpose of administering epinephrine is to cause vasoconstriction and increase cardiac output. In other words, it contracts the heart and increases your heart rate to “revive it.”

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Epinephrine is also a first-line treatment for anaphylaxis. The condition of anaphylaxis can develop due to a severe allergic reaction and can even lead to death in the event of extreme bronchoconstriction. In these cases, medical professionals will administer this drug since it’s able to dilate the respiratory tract and allow the patient to breathe.

Joint administration with local anesthetics

Epinephrine is added to a variety of local anesthetics administered as injectables. The reason for this combination is that the vasoconstrictive effects of adrenaline make it possible to delay absorption and thus prolong the effect of the anesthetic drug.

That being said, however, some of the side effects of using local anesthetics with epinephrine may be due to the effects of the epinephrine and can include:

  • Apprehension/uneasiness
  • Tachycardia
  • Tremors

Possible side effects of epinephrine

Adrenaline side effects of epinephrine

Using this substance can have possible side effects and complications, especially when administered intravenously and intracardially. Possible adverse reactions to epinephrine include:

  • Palpitations and tremors.
  • Tachycardia.
  • Cardiac arrhythmias.
  • Anxiety and hypertension.
  • Headaches.
  • Acute pulmonary edema.

Also, there are several contraindications for epinephrine. In these conditions, epinephrine is not an appropriate medication. For example, for patients being treated with non-selective beta-blocker drugs, epinephrine is not an appropriate medication. This is because it can lead to a very dangerous drug interaction, which can cause severe hypertension and even cerebral hemorrhage.

Although many people believe that the administration of epinephrine can cause heart failure due to its strong vasoconstrictor effect, this is not true. The coronary arteries have only one type of receptor that triggers vasodilation, not vasoconstriction, when in contact with adrenaline.


Epinephrine, or adrenaline, is a drug that administered through different channels depending on the patient’s condition and situation. Additionally, it’s a valuable treatment for cardiac arrest and anaphylactic reactions.

There are types of epinephrine you can self-inject if you are at risk for suffering from anaphylactic shock.

Like all medicines, it is not free of side effects, which you should take into account when administering this medication.

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  • Cardona Dahl, V. (2010). Guía de actuación en anafilaxia. Medicina Clínica. https://doi.org/10.1016/j.medcli.2010.10.003
  • Ateneo, E. El. (2006). Drogas vasoactivas en el paciente critico. Medicina Intensiva.