Adrenaline: Effects, Indications & Triggers

Adrenaline, a hormone that also functions as a neurotransmitter, plays several key roles in the body. It increases heart rate and blood pressure, enhances breathing, reduces pain sensitivity, and heightens brain alertness.

Also called epinephrine, adrenaline is made in the adrenal glands. It is naturally released in response to stress, strong emotions, physical activity, infections, or illness.

As a medication, adrenaline (epinephrine) can be given by a doctor or nurse in hospital settings to treat emergencies like anaphylaxis, severe asthma, and cardiac arrest. It is also available as a prescription auto-injector for people at high risk of severe allergic reactions.

Main effects

The main effects of the hormone adrenaline in the body are:

• Increasing heart rate and blood pressure;

• Increasing blood flow to the muscles;

• Increasing strength and performance;

• Improving breathing and lung capacity;

• Raising blood sugar levels to provide energy;

• Activating the brain, making it more alert;

• Reducing pain;

• Dilating the pupils, making it easier to see in dark environments;

• Slowing down digestion;

• Causing sweating;

• Increasing contraction of the skin muscles, causing goosebumps.

Adrenaline is a hormone and neurotransmitter that plays an essential role in the body’s response to stress and in emergency situations. It is produced mainly in the adrenal medulla.

These effects are also influenced by norepinephrine and dopamine, other neurotransmitter hormones produced by the adrenal glands that also affect the body and brain.

Is epinephrine the same thing as adrenaline?

Yes. Epinephrine and adrenaline are synonyms and refer to the same substance, which acts as both a hormone and a neurotransmitter.

In the US, “epinephrine” is more commonly used when referring to this substance as a medication.

Adrenaline vs norepinephrine

Norepinephrine is a hormone and neurotransmitter produced in the adrenal glands from dopamine. As a medication, norepinephrine is mainly used in emergency situations involving dangerously low blood pressure.

Adrenaline is also produced in the adrenal glands, but it is synthesized from norepinephrine. As a medication, adrenaline is commonly used to treat anaphylaxis and severe asthma.

Indications for use

Adrenaline in medication form is indicated in situations such as:

• Treating severe allergic reactions, as it relaxes airway muscles, reduces throat swelling, and helps prevent an excessive drop in blood pressure. According to the CDC, epinephrine is the first-line treatment for anaphylaxis;

• Treating cardiovascular emergencies, such as cardiac arrest or shock, based on American Heart Association (AHA) guidance;

• Managing severe asthma attacks that do not respond well to usual treatment measures;

• Controlling minor bleeding during small skin or dental procedures;

• Prolonging the pain-relieving effect when used together with local anesthetics.

Routes of administration for adrenaline (epinephrine) injection include intramuscular, intravenous, and subcutaneous routes.

Epinephrine is not available over the counter as a medication. It is administered in hospitals and emergency settings, while auto-injectors like EpiPens (prescription-only devices) are carried by individuals at high risk for severe allergic reactions.

Adrenaline triggers

Adrenaline is activated and released in situations such as:

• Stressful conditions, as a response to an emotional, physical, or environmental stressor or threat;

• Strong emotions, anxiety, and fear;

• Health conditions, such as infections or serious illnesses;

• Physical activity, especially high-intensity or “extreme” sports such as climbing or jumping.

The release of adrenaline into the bloodstream happens quickly, often within minutes. This rapid release is commonly described as an “adrenaline rush.”

When stress or danger passes, the adrenal glands stop releasing adrenaline. Even so, its effects can last from about 20 minutes up to around an hour after stress levels decrease.

Potential risks

When the body produces too much adrenaline, possible symptoms include palpitations and tachycardia, dizziness and vertigo, nervousness, agitation, and irritability.

Excess natural adrenaline can also cause insomnia, vision changes, heavy sweating, cold or pale skin, and severe headache.

Over the long term, excess adrenaline may contribute to high blood pressure, anxiety, and weight loss.

Side effects

Possible side effects of adrenaline (epinephrine) medication include:

• Tachycardia, palpitations, arrhythmia, chest pain, and high blood pressure;

• Anxiety, apprehension, nervousness;

• Tremors, weakness, dizziness, and headache;

• Excess saliva and high blood sugar;

• Excessive sweating;

• Ringing in the ears;

• Shortness of breath;

• Cold hands and feet.

At high doses, adrenaline may cause severe arrhythmias, a sudden increase in blood pressure, cerebral hemorrhage, pulmonary edema, and reduced blood flow (ischemia) to the extremities and internal organs.

Epinephrine may also lead to gangrene, especially if it is administered in areas like the fingers, nose, ears, or penis.

Contraindications for use

Adrenaline (epinephrine) should not be used by anyone who is allergic to any component of the product.

It also should not be administered to people who have used cocaine, or who are taking beta-blockers such as atenolol, sotalol, or propranolol.

Epinephrine is also not indicated during labor, and it is not recommended for people with long-standing bronchial asthma.

Use of adrenaline as a medication should always be guided by a healthcare provider, especially because emergency dosing and monitoring are typically required.