CPR First Aid


How do Beta Blockers Work to Lower Blood Pressure?

Beta blockers are often prescribed as treatment for heart or circulatory system conditions like hypertension. Know more about this medication and its use.

Beta blockers are a type of medication that is used to reduce blood pressure. They work by blocking the effects of adrenaline on the heart. They help slow down the heartbeat and reduce the amount of blood pumped out of the heart. They can help to reduce the symptoms of high blood pressure, such as chest pain and shortness of breath. Beta blockers can also help to protect the heart from damage caused by a heart attack.

What Do Beta Blockers Do for You?

Beta blockers work by blocking the beta-adrenergic receptors. These receptors are found in the heart, lungs, and blood vessels. When the receptors are blocked, it causes the heart to beat more slowly and with less force. It lowers blood pressure and makes it easier for the heart to pump blood throughout the body. Beta blockers also widen blood vessels, which can also help to lower blood pressure.

Beta blockers slow heart by blocking beta receptors in heart, lungs, & blood vessels.

What are Beta Receptors?

These are cells found on nerve cells in the brain and the body. They help control the part of the brain in charge of the heart and blood vessels.

Beta receptors are found throughout the body and have different functions depending on their location. There are three subtypes, namely:

Beta-1 (B1)

Found in the heart and kidneys. When activated, there is an increase in heart rate and pumping force. There is also a release of the kidney enzyme, renin.

Beta-2 (B2)

Located in the smooth muscle, respiratory and nervous system, and blood vessels. Their following functions are:

Respiratory – acts on smooth muscles to relax for easier breathing

Heart – pumping force and heart rate increase

Nervous system – causes muscle tremors

Blood vessel – smooth muscles relax to lower blood pressure and widen blood vessels

Liver – glycogen to glucose conversion is activated

Beta-3 (B3)

Situated in the urinary bladder and fat cells. Their functions include causing fat cells to break down, tremors, bladder muscle relaxation, and increasing capacity.

Medication for the Heart and Circulatory System

The primary use of beta blocker medications is to treat high blood pressure (hypertension). Beta blockers can be used alone to treat hypertension or with other medicines to lower blood pressure. They may also be used while treating certain health conditions to help lower your heart rate and blood pressure.

"Manage hypertension: beta blockers lower heart rate & BP; used alone or with other meds."

Treatment for Several Conditions

Beta blockers are used to treat many conditions in Southport; here are some of them:


Angina is a condition characterised by chest pain or discomfort when the heart does not receive enough oxygen. Beta blockers reduce the heart’s oxygen demand by slowing the heart rate.


Problems with the rate or rhythm of your heartbeat are called arrhythmias. They can cause your heart to beat too fast, slow, or irregularly. Beta blockers are a medication often used to treat arrhythmias by helping control the heart rate and rhythm. Beta blockers work by blocking the effects of the hormone adrenaline on the heart. It can help to slow down the heart rate and make it more regular.


While beta blockers are not typically considered first-line treatment for anxiety, they may be prescribed if other treatments haven’t worked or if the person has anxiety with physical symptoms.


Migraine is a type of headache that can be very severe. Beta blockers can help to treat migraines by lowering blood pressure. They can be taken as a preventative measure to help reduce the frequency and severity of migraines.

Heart Failure

Beta blockers slow down a person’s heart rate and allow for extended periods where their blood can’t flow as fast, which is good if atrial fibrillation is present. They also reduce the risks of having a second heart attack.

Side Effects

Although generally considered safe or usually well tolerated, some potential beta blocker side effects can occur, such as:

  • fatigue
  • cold hands and feet
  • dizziness
  • nausea
  • decreased heart rate
  • constipation
  • impotence

A doctor’s visit is necessary if you or anyone you know has any of these side effects. Beta blockers can also interact with other medications, so be sure to tell your doctor about all the medications you are taking.

When Should You Take Beta Blockers?

Doctors may prescribe beta blockers as treatment if you have been diagnosed with:

  • High blood pressure
  • Congestive heart failure
  • If you have had a heart attack
  • Anxiety or panic disorder
  • Glaucoma

They can also be taken to prevent or relieve symptoms of:

  • Migraines or cluster headaches
  • Essential tremor
  • Raynaud’s phenomenon – decreased blood flow to the fingers
  • Hyperthyroidism or thyrotoxicosis – overactive thyroid gland
  • Pheochromocytoma – non-malignant tumour of the adrenal gland

Commonly Prescribed Beta-blockers in Australia

Beta-blockers are the most commonly prescribed class of blood pressure drugs in Australia. They are generally considered safe and effective when used as directed. Two of these drugs are atenolol and metoprolol.


Used to treat angina and hypertension. It is also used to prevent migraine headaches and to treat heart attacks.

Health and Safety Tips

A person should not use atenolol if they have asthma or certain heart conditions such as slow heartbeats, heart block, or cardiogenic shock. In addition, atenolol can pass into breast milk and may harm a nursing baby.


Used to treat high blood pressure, angina, and other heart conditions. Metoprolol can cause side effects such as fatigue, dizziness, and low blood sugar levels. If you experience any of these side effects, contact your doctor.

How long does a beta blocker take to start working for blood pressure?

Carvedilol is a prescription drug that makes the heart work more slowly; the rhythm slows down and improves circulation around your body’s systems, including brain function. It is taken once or twice daily for best results, although you may notice an improvement within 1 hour.

Beta Blocker Contraindications

A contraindication is generally a condition that increases the risk of harmful side effects from a medication or medical procedure. Who should not use a beta blocker? Contraindications include conditions such as:

  • asthma
  • bradycardia – slow heart rate
  • peripheral vascular disease (PVD)
  • diabetes mellitus
  • chronic obstructive pulmonary disease (COPD)

Beta blockers should be used cautiously in patients with these conditions and only if the potential benefits outweigh the risks.

Beta blocker: Contraindicated for high-risk individuals.

Do Beta Blockers Weaken the Heart?

There are a few ways that beta blockers can weaken the heart.

One is by reducing the heart’s output of blood. This can lead to low blood pressure, which can cause lightheadedness, dizziness, fatigue, and even fainting.

Another way is by interfering with the electrical signals that tell the heart when to beat. It can cause irregular heart rhythms, which can be dangerous.

Finally, beta blockers can also increase the risk of heart attacks and strokes by increasing the levels of cholesterol and triglycerides in the blood.

Food to Avoid

Some foods should be avoided if a person is taking beta blockers to prevent potential interactions. These include:

Grapefruit and Grapefruit Juice

Grapefruit can increase the level of beta blockers in your blood, leading to side effects such as low blood pressure and irregular heartbeat.

St John’s Wort

This herbal supplement can decrease the level of beta blockers in your blood, making them less effective.


Alcohol can interact with beta blockers and cause side effects such as dizziness, lightheadedness, and low blood pressure.

Foods High in Fat

High-fat meals can slow down the absorption of beta blockers, making them less effective.

Smoking should also be avoided as it can interact with beta blockers and cause side effects such as increased heart rate and blood pressure. If any other medications are taken, a doctor’s consultation or advice from the pharmacist is needed before starting beta blockers as there may be potential drug interactions.

How Can I Apply This Information in Emergency Cases?

Being a first aider in Southport QLD, it is essential to know what to administer and what not to an affected person. Enrol at CPR First Aid and learn first aid practices at Cnr Ferry Rd and Cotlew St E, Southport 4215, and many more locations. Call us!

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