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- Pharmacist Only Medicine
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Adrenaline is a naturally-occurring chemical that is released in response to stress.
It binds to alpha and beta adrenergic receptors, which are found all over the body, especially on the heart, lungs and blood vessels. When beta receptors are activated, they cause the heart to beat faster and more strongly, and increase the width of the airways in the lungs.
There is also has a stimulating effect on the brain. When adrenaline binds to alpha receptors this causes narrowing of blood vessels, which increases blood pressure. All of these actions prepare the body to cope with a stressful situation.
Adrenaline is the first line of treatment in life-threatening allergic reactions (anaphylaxis). In this situation the airways may narrow making it more difficult to breathe. One of the most important effects of adrenaline is to open up the airways to ease breathing.
A second important effect is the narrowing of blood vessels which prevents or reverses falls in blood pressure. Adrenaline is also responsible for relieving itching, redness and swelling associated with anaphylactic reactions.
As anaphylactic reactions (life-threatening allergic reactions) can develop within minutes of exposure to the trigger factor (which could be a bite or sting, food e.g. peanuts, drug or other substance) individuals who are at risk are sometimes advised to carry an automatic injection device. This can be used to give a dose of adrenaline immediately.
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