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What Are Beta-Blockers and What Do They Do?

Beta-blockers, also known as beta-adrenergic blocking agents, are most commonly known for their role in lowering blood pressure. Beta-blockers can lower blood pressure, heart rate, or cardiac contractility, depending on which cell receptors they target.

Beta-blockers can be effective in different locations throughout the body. The medication is intended to block the effects of the hormone epinephrine (adrenaline). Tiny proteins, called beta-receptors, are outside many of the body’s cells. There are three types of beta-receptors:

  • Beta 1 receptors are found almost exclusively in heart cells.
  • Beta 2 receptors are mostly in lung and blood vessel cells, with some in heart cells.
  • Beta 3 receptors are on fat cells.

Beta-receptors latch onto different chemicals in the body that act like messengers, such as epinephrine. The body then responds to these messengers by making the heart beat faster, constricting blood vessels, relaxing airways, or increasing blood pressure.

Beta-blockers block the beta-receptors and their response to the body’s chemical messengers. This leads to a slower heart rate, relaxed blood vessels, and lower blood pressure.

The beta-blockers that have been approved for use in the United States fall into three general groups. These groups are classified by how the medication blocks the beta-receptors.

  1. Nonselective beta-blockers are the earliest developed beta-blockers. They affect both beta 1 and beta 2 receptors, so they can affect cardiac (heart) and pulmonary (lung) actions. This type of beta-blocker is usually not appropriate for patients with lung conditions like asthma.
  2. Cardioselective beta-blockers are designed to block only cardiac beta 1 receptors. Because of this, they may be more appropriate for patients with lung conditions.
  3. Third-generation beta-blockers can also block other receptors in the body (such as alpha-receptors). This helps relax blood vessels.

Depending on coexisting illnesses and sometimes in combination with other medication, health care providers typically prescribe beta-blockers to prevent, treat, or improve symptoms from the following conditions:

  • Arrhythmia (irregular heart rhythm)
  • Migraine
  • Heart attacks
  • Angina (chest pain)
  • Heart failure
  • Certain types of tremors

The blood pressure level that is considered “high” (hypertension) has changed over the last couple of decades. 

Health care providers typically don’t prescribe beta-blockers as the first treatment for someone who only has high blood pressure. If someone’s hypertension has been unresponsive to other medications (like a diuretic), health care providers may prescribe beta-blockers instead. Beta-blockers address a couple of the potential causes of hypertension. They can lower blood pressure by slowing down the heart rate and easing the force of its contractions.

Health care providers also use beta-blockers to treat symptoms of hyperthyroidism, including tremors, elevated heart rate, and heart palpitations.

Like hyperthyroidism, anxiety can produce physical symptoms that can be alleviated by a beta-blocker. Beta-blockers can be helpful in alleviating anxiety symptoms such as rapid heart rate, shaking, and trembling. Health care providers typically prescribe a beta-blocker for anxiety for short-term anxiety situations, such as stage fright or social anxiety. Beta-blockers come with side effects, so make sure to only use them as prescribed by your health care provider.

Beta-blockers, like most medications, can have a variety of side effects. Side effects related to beta-blockers can vary based on the dosage. The lower the dose, the less noticeable the side effects should be. Your health care provider may adjust your dose or switch the specific drug type a couple of times. They will work with you to find the drug and dosage that is the most effective and leads to the fewest side effects. Many health care providers recommend patience as the body adjusts to the appropriate dosage.

Some of the more common side effects of beta-blockers include:

  • Cold hands or feet
  • Fatigue
  • Weight gain
  • Dizziness or lightheadedness
  • Headache
  • Decreased sex drive
  • Upset stomach, constipation, and/or diarrhea

Less common side effects include:

  • Mild depression
  • Shortness of breath
  • Trouble sleeping/disturbed dreams

Health care providers consider a few different things before prescribing a beta-blocker. Beta-blockers can trigger asthma attacks in people with asthma. Beta-blockers can also negatively affect cholesterol and triglyceride levels, decreasing your good cholesterol (HDL) and elevating your triglycerides. Beta-blockers can also block symptoms of low blood sugar (e.g., rapid heartbeat), so diabetics taking a beta-blocker will need regular blood sugar checks.

If you are concerned about the side effects of your beta-blocker, reach out to your health care provider. Quitting your beta-blocker or decreasing the dose can increase your risk of heart attack or other significant heart problems. Don’t adjust your dose or stop taking the medication without consulting your health care provider. 

Millions of Americans take beta-blockers. Beta-blockers can affect the body in a variety of potentially helpful ways. This breadth of action can also cause complications, so talk with your health care provider about your medical and family history before beginning a new prescription. Be patient. It may take a while to figure out your dosage, but you should be feeling better soon.

https://www.fda.gov/consumers/free-publications-women/high-blood-pressure-medicines-help-you#Beta_Blockers

https://www.health.harvard.edu/heart-health/beta-blockers-cardiac-jacks-of-all-trades

https://www.mayoclinic.org/diseases-conditions/high-blood-pressure/in-depth/beta-blockers/art-20044522

https://www.health.harvard.edu/newsletter_article/beta-blockers-for-blood-pressure-a-second-opinion
20044522

https://www.mayoclinic.org/diseases-conditions/hyperthyroidism/diagnosis-treatment/drc-20373665

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