CPR First Aid

Why Do Vasoconstrictors Raise Blood Pressure?

Vasoconstriction is a natural process in the body. When using vasoconstrictors to treat some conditions, we can expect a possible rise in blood pressure.

Vasoconstrictors are a type of drug that causes the blood vessels to narrow. This, in turn, raises blood pressure. There are many different types of vasoconstrictors, and they are used for a variety of purposes. Understanding how they work is important for those who take them, as well as for those who care for someone who does.

What is Vasoconstriction?

Vasoconstriction is the narrowing of blood vessels due to muscle contraction, specifically the arteries and arterioles. This process decreases blood flow – otherwise known as vascular resistance – and can raise blood pressure. This process also helps maintain arterial pressure. On the opposite end is a process called vasodilation which is when blood vessels widen.

Vasoconstriction is a natural process that happens in response to various stimuli, including:

  • Cold temperatures
  • Emotional stress
  • Certain medications – epinephrine and norepinephrine
  • The sympathetic nervous system
  • Hormones – angiotensin II and endothelin
  • Smoking
  • Inflammatory mediators – histamine and leukotrienes

Abnormal vasoconstriction is also possible though, with conditions like Raynaud’s phenomenon constricting vessels and affecting vessel walls of a person’s hands and feet. It also takes place during hypoxia, where there is not enough oxygen in the body.

Chronic vasoconstriction can lead to serious coronary events or heart problems such as heart disease, heart failure, and stroke. Furthermore, it also puts people with coronary artery diseases at risk if they become under duress.

Treatment for vasoconstriction generally focuses on managing the underlying medical conditions. In some cases, medication may be necessary to relieve symptoms. In order to correctly respond to certain emergency scenarios brought about by complications, a Southport first aid qualification can help the affected person. In turn, you can save a life.

Blood vessels narrow due to muscle contraction, reducing blood flow, raising pressure. Vasodilation widens vessels.

How Do Vasoconstrictors Work?

Vasoconstrictors work by stimulating the sympathetic nervous system. It is also regulated by the autonomic nervous system. This system is responsible for the ‘fight or flight response. When it is activated, it causes blood vessels to constrict and blood pressure to rise.

Vasoconstrictors are typically given intravenously (through a vein). These drugs, however, can have serious side effects, so they should only be used under the supervision of a healthcare provider.

In truth, this is a simplified explanation of how vasoconstrictors work. Our bodies have many working parts and processes when it comes to blood and its flow. These include things like capillaries, cardiac output, the endothelium, vascular tone, perfusion, and much more.

Going even smaller, vasoconstrictors are certain chemicals and enzymes that work on neurotransmitters. These include things like agonists, calcium channel blockers, ATP, thromboxane, and many other things.

If you are interested in learning more about this fascinating process, you can access PubMed which is a free online resource to use.

Do Vasoconstrictors Raise Blood Pressure?

The volume of space inside the affected vasculature is reduced by vasoconstriction. There is a decrease in blood flow resulting from decreased blood vessel volume. Concurrently, the force of resistance of vascular resistance increases, causing blood pressure to rise.

Blood vessels narrow due to muscle contraction, reducing blood flow, raising pressure. Vasodilation widens vessels.

In What Ways Can Vasoconstrictors Be Useful in the Body?

Vasoconstrictors can be used in emergency situations like low blood pressure, shock, and head injuries to help raise blood pressure. They can also be used to help stop bleeding, to reduce swelling and inflammation, and increase the .

Vasoconstrictor drugs can also be used to treat migraines and cluster headaches by narrowing the blood vessels in the head. In some cases, vasoconstrictors may be used as a nasal spray to help with nasal congestion.

Other than these, peripheral vasoconstriction is a normal process that happens when people are exposed to cold weather. After being exposed to the elements, this helps keep people from losing too much heat and maintain their body temperature.

How Do Vasoconstrictors Become Harmful?

Vasoconstrictors can become harmful in a few different ways. First, if blood vessels are constantly constricted, it can lead to high blood pressure.

Second, constricted blood vessels can decrease the amount of blood flow to vital organs, which can cause problems like organ damage or failure. For instance, it can affect the blood vessels of the lungs, causing pulmonary hypertension.

Furthermore, it can affects different parts of the body. One example are the eyes where dilation is triggered. While the ability to receive more light in the eyes is generally favourable, if it happens continuously, it could cause some problems to one’s eyes.

Finally, vasoconstrictors can increase the risk of clotting, which can lead to strokes or heart attacks. Therefore, it is important to be aware of the potential risks of vasoconstriction and to talk to a doctor if you are concerned about any of these risks.

Commonly Used Vasoconstrictors in Australia

There are a number of vasoconstrictors commonly used in Australia. Some of the more popular ones include:


A medication that is used to narrow blood vessels. It is often used as a nasal decongestant or to treat low blood pressure.


A hormone that is released by the adrenal gland in response to stress. It acts on the sympathetic nervous system to increase heart rate and blood pressure.


Norepinephrine is another hormone that is released by the adrenal gland. It acts on both the sympathetic nervous system and the smooth muscle of blood vessels to cause vasoconstriction. For both norepinephrine and epinephrine, the vasoconstrictors interact with the adrenergic receptors.


A hormone that is released by the pituitary gland. It acts on the smooth muscle of blood vessels to cause vasoconstriction. It is also involved in water balance and can be used to treat diabetes insipidus.

Angiotensin II

A hormone that is produced in the body in response to low blood pressure. It acts on the smooth muscle of blood vessels to cause vasoconstriction and increased water retention by the kidneys.


A hormone that is produced by the adrenal gland. It acts on the kidneys to cause increased water retention and sodium absorption. This leads to an increase in blood volume and blood pressure.

Are Vasoconstrictors Available Over-the-counter in Australia?

Vasoconstrictor medications over-the-counter can vary from country to country. However, in Australia and Southport QLD, it is generally not possible to purchase these types of medications without a valid prescription from a medical professional.

Conditions and Effects Vasoconstrictors Are Used For

Here we can understand further how vasoconstrictors help in some common emergency scenarios as advised or administered by a medical professional.

"Learn vasoconstrictors' role in emergencies, guided by medical experts."


Shock is a potentially life-threatening condition that occurs when the body is unable to circulate blood effectively. This can lead to organ damage and even death. Vasoconstrictors are drugs that help to constrict (narrow) the blood vessels, which in turn increases the blood pressure and helps to improve blood circulation, which may help to save the person’s life.


Vasoconstrictors can be used to control bleeding by decreasing the amount of blood that is lost. In addition, they can also be used to improve blood pressure and reduce the workload of the heart.

Head Injuries

Vasoconstrictors can be used to help control bleeding in head injuries. They work by constricting the blood vessels, which decreases the amount of blood that is able to flow to the injury site. This can help to reduce the severity of the injury and improve the chances of a successful recovery. Vasoconstrictors are typically only used in cases of severe head injuries where other methods of control have failed.

Low Blood Pressure

Vasoconstrictors can raise blood pressure by increasing the total peripheral resistance to blood flow. Some commonly used drugs include epinephrine, norepinephrine, and phenylephrine, especially in situations where there is a risk of hypotension (low blood pressure).


One way that vasoconstrictors can help with migraines is by decreasing the amount of blood flowing to the brain. This can help to reduce the pain and inflammation associated with migraine headaches. Vasoconstrictors can also help to improve blood flow to the brain by constricting the blood vessels. This can help to relieve some of the symptoms of migraine, such as nausea and sensitivity to light and sound.

When to Avoid Vasoconstrictors?

Vasoconstrictors should be used with caution in patients with cardiovascular disease, hypertension, cerebrovascular disease, diabetes, and renal impairment. They should also be used with caution in the elderly and pregnant women.

To sum up, the body naturally employs vasoconstriction to keep its systems in balance. When blood vessels are constricted, it requires more force for the blood to flow through them, raising blood pressure. Contrarily, vasoconstrictors can either be beneficial or harmful to a person, which is why it is crucial to seek medical advice.

CPR First Aid (RTO 21903) offers accredited courses such as adult first aid at Cnr Ferry Rd and, Cotlew St E, Southport 4215. For more information, send us an enquiry and we’ll be happy to respond and walk you through the first aid certification process.



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