Adrenaline
Key facts
- Adrenaline is a hormone that your body naturally releases from your adrenal gland.
- Adrenaline causes changes in your body that help you to act in a sudden stressful situation — also known as a 'fight or flight response'.
- Adrenaline is also used sometimes as a medicine, for example, an adrenaline injection in severe allergic reactions (anaphylaxis).
- If you or someone else is having symptoms of severe allergy (anaphylaxis), use an adrenaline (epinephrine) autoinjector first — then call triple-zero (000) and ask for an ambulance.
What is adrenaline?
Adrenaline is a hormone that helps you react quickly if you are faced with an exciting, stressful or dangerous situation. This is known as the 'fight-or-flight response'. In this type of situation, your brain sends chemical messages to your adrenal glands (located just above the kidneys) to start releasing the hormone into the blood. You will feel the effects of the adrenaline within minutes.
When the stress has passed, the glands stop producing adrenaline. You might still feel the effects of adrenaline — such as trembling, your heart beating fast or looking pale — for around 20 minutes.
Adrenaline is also used as a medicine in emergency situations, such as a severe allergic reaction.
Outside of Australia adrenaline may be called epinephrine.
What are the effects of adrenaline?
Adrenaline makes your heart beat faster and your lungs breathe more efficiently. It causes your blood vessels to send more blood to your brain and muscles, increases your blood pressure, makes your brain more alert, and raises blood sugar levels to give you energy. Your pupils grow larger and you sweat. You don't feel as much pain, so you can keep running or fighting if needed, even if you are injured. These temporary effects on your body allow you to perform better during a stressful situation.
When is adrenaline used as a medicine?
Adrenaline is a medicine used to treat a severe allergic reaction (anaphylaxis) in an emergency. It may also be given in different forms during cardiac arrest, croup and asthma.
You can take a dose of adrenaline by using an autoinjector. If you have a health condition that means you may need adrenaline urgently (such as severe allergies), you can learn how to use an EpiPen or Anapen adrenaline autoinjector.
Adrenaline works by quickly reducing swelling in your throat, opening up your airways and preventing your blood pressure from falling too low.
Adrenaline is injected into the large muscle in the thigh and can save your life. If you are not feeling better and breathing easily 5 minutes after your first adrenaline injection, inject another dose of adrenaline from a new packet.
If you have been given an adrenaline injection at home or anywhere outside of a hospital it is important to attend a hospital, even if you are feeling much better. Hospital doctors will monitor you for at least 4 hours.
If you or someone else is having any of these symptoms, and you have an adrenaline (epinephrine) autoinjector, use it first. Then call triple-zero (000) and ask for an ambulance:
- difficulty or noisy breathing
- wheeze
- sudden, intense coughing
- difficulty talking
- ongoing dizziness or collapse
- tongue swelling
- tightness in the throat
What if I have both asthma and allergy?
Asthma, food allergy and anaphylaxis often occur in the same person. Asthma increases your risk of having anaphylaxis, so if you have asthma and an allergy, your doctor may also prescribe an adrenalineautoinjector, for you to use if you need it. If you have asthma and suddenly have problems breathing:
- always use the adrenaline autoinjector first
- use your asthma reliever medicine
- call triple zero (000) for an ambulance if you still have trouble breathing.
Follow your Anaphylaxis Action Plan and then apply asthma first aid, then call triple zero (000) and ask for an ambulance if you need it.
Is having too much adrenaline a problem?
If you have too much adrenaline, it can lead to symptoms including:
- dizziness
- changes to your vision
- heart palpitations
- feeling irritable and jittery
- difficulty sleeping (insomnia)
Some rare medical conditions, such as a tumour on the adrenal glands, can also cause you to have too much adrenaline.
Over time, high levels of adrenaline can cause:
- high blood pressure
- weight loss
- anxiety
- increased risk of a heart attack or stroke
Is having too little adrenaline a problem?
Having too little adrenaline is very rare. If you don't have enough adrenaline, it would stop your body from being able to react properly in stressful situations.
How can I adjust my adrenaline levels?
Increased adrenaline levels may be related to your body's response to stress. If this is the case, you may be able to manage your stress in a healthy way such as:
- exercising
- meditating or doing another relaxation technique
- sleeping well
- eating a healthy diet
- reducing caffeine and alcohol
- speaking to a doctor or mental health professional
When should I see my doctor?
If you have allergies, you could be at risk of anaphylaxis. You should discuss an 'anaphylaxis action plan' with your doctor.
If you are at risk of anaphylaxis, your doctor will prescribe adrenaline, based on your age and weight. There are 3 doses of adrenaline autoinjector available in Australia and New Zealand:
- 150 microgram adrenaline, for children 7.5 to 20kg
- 300 microgram adrenaline, for adults and children over 20kg
- 300 or 500 microgram adrenaline, for adults and children over 12 years and 50kg
Resources and support
For more information on adrenaline autoinjectors, including videos on how to use them, visit the ASCIA website.
You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available 24 hours a day, 7 days a week.
Learn more here about the development and quality assurance of healthdirect content.
Last reviewed: August 2023
