Beta Blockers: Are They Safe to Use If You Have Asthma?
Traditionally, people with asthma who were on a type of medicine called a beta agonist were cautioned against using a type of heart medicine called a beta blocker. The concern was that these two types of medicine might interact in a way that was harmful to the patient. In this post, I'll give you the facts about both types of medicine and whether they truly do pose a risk when used together.
What is a beta blocker?
Beta blockers are a type of medicine developed in the 1960s that interfere with the body's "fight or flight" response to stress.1 In response to stress or danger, your sympathetic nervous system releases adrenaline and noradrenaline. These are hormones that act as chemical messengers. Tiny proteins on the outer surface of many different types of cells called beta receptors sit and wait to latch on to these hormones. They then direct the body to respond in these ways:1,2
- The heart starts to beat faster
- Your blood vessels narrow and tighten
- The airways relax
- You sweat excessively
- Your blood pressure rises
All of those reactions can be useful in people who are in danger or who are responding to stress. But, in those with certain health conditions, such as angina or high blood pressure, those responses can be harmful. That's where beta blocker medicines come in. They latch on to the beta receptors so that adrenaline and noradrenaline can't bind to them.
As a result, this happens:2
- Your heart beats more slowly
- Electrical signals in the heart communicate better
- Your blood vessels throughout the body relax
- Blood pressure lowers
When are beta blockers used?
Doctors prescribe beta blocking medicines for a wide variety of heart health problems, including:2
- Congestive heart failure
- After a heart attack to help heal the heart
- Irregular heartbeats, such as arrhythmia or palpitations
- High blood pressure
But they may also be used for other health problems, such as:1,2
- Essential tremors
- Overactive thyroid
Newer medicines are often used these days, but millions of people still take a prescription beta blocker.2
Types of beta blockers
Different types of beta blockers work in slightly different ways. In return, they have different uses. Here are some of the types available today:2
Nonselective beta blockers
This is the oldest type, and the name says it all. They act on beta receptors all over the body, sometimes unnecessarily. This is the type of beta blocker that people with respiratory conditions are usually cautioned against. Examples include:
- propanolol (AKA Inderal, Betachron, InnoPran, Hemangeol)
- penbutolol (AKA Levatol)
- nadolol (AKA Corgard)
- pindolol (AKA Visken)
- sotalol (AKA Betapace, Sorine)
Cardioselective beta blockers
This type of medicine was specifically designed to block the beta receptors only in heart cells. Therefore, they are generally considered to be safe for people with asthma and other lung conditions.3 Examples include:
- atenolol (AKA Tenormin)
- timolol (AKA Blocadren, Timolide)
- metoprolol (AKA Lopressor, Toprol XL)
Third-generation beta blockers
This is the newest type and has been designed to block another type of receptor called an alpha receptor. They help relax blood vessels even more than the other types. Examples include:
- carvedilol (AKA Coreg)
- labetalol (AKA Normodyne, Trandate)
- nebivolol (AKA Bystolic)
Beta blockers can have side effects like most medicines, but in this case, they tend to be more annoying than dangerous.
What is a beta agonist?
Beta agonists are a type of medicine used to treat asthma (and sometimes other lung conditions).4 They are sometimes known as bronchodilators because they relax the airways. Like beta blockers, beta agonists act on the beta receptors in certain types of cells. Namely, they act on the beta receptors found in smooth muscle tissue. However, today's beta agonists are designed to focus primarily on airway smooth muscle tissue, while minimizing the effects on smooth muscle found in the heart.5
Rather than interfering with the beta receptors, however, beta agonists enhance the action of certain enzymes that bind to the beta receptors. The result is relaxation of the lining of the airways. Overall, these are the benefits of using a beta agonist:6
- Promote better control of asthma
- Reduce asthma symptoms, especially at night
- Improve lung function
- Reduce risk of exacerbations
- Minimize the required dose of inhaled steroids
When are beta agonists used?
Beta agonists are used both for asthma and for COPD. In asthma, they are considered essential treatment, usually in combination with inhaled steroids.6 In people with COPD, they may or may not be used, depending on the patient's respiratory status.
Types of beta agonists
Beta agonists come in two different types:4
Short-acting beta agonists, or SABAs
This is your rescue inhaler, which provides quick relief of your asthma symptoms. It should not be used more than twice a week, or else it's a sign that your asthma is not well-controlled. People with exercise-induced asthma also use SABAs before exercise to prevent symptoms. Examples include:
- albuterol (AKA AccuNeb, Proventil HFA, ProAir HFA, Ventolin HFA)
- levalbuterol (AKA Xopenex)
Long-acting beta agonists, or LABAs
These are also known as controller medicines, because they are taken every day to prevent, or control, asthma symptoms. For asthma, they are usually only used in combination form with a steroid medicine. Examples of the LABA/steroid combination medicines include:
- formoterol and budesonide (AKA Symbicort)
- formoterol and mometasone (AKA Dulera)
- salmeterol and fluticasone (AKA Advair)
How might the two types of medicines interact?
In years past, experts were concerned that beta blocker medicines would interfere with how well beta agonists worked. They also feared that beta blockers would cause further constriction of already tight and narrow airway muscles in people with asthma. As a result, doctors were often reluctant to prescribe a beta blocker to a patient with asthma. Obviously, if the patient also had other health conditions that could benefit from a beta blocker, this could be problematic.
Fortunately, there have been many studies that have looked at beta blocker use in people with asthma.3 However most of these studies involved the use of cardioselective beta blockers. Researchers have found that this type of beta blocker presents very limited risk to people with asthma, as long as the recommended doses are followed. This is true even if the person with asthma is on a beta agonist.
Nonselective beta blockers have been found to decrease the response to beta agonists and should not be prescribed for people with asthma, if at all possible.3
These scientific terms for medicine may seem confusing. But if you think of beta blockers as beta antagonists, it's easier to understand that they are basically the opposite of beta agonists. In general, they work in opposite ways on the beta receptors in our cells. Fortunately, modern medicines have been designed to have very specific effects in specific parts of our bodies.
If you have asthma and also another condition that might benefit from a beta blocker, discuss the pros and cons of taking both types of medicine with your doctor. Keep in mind that not using a beta blocker to treat a medical condition can also present some risk. Many times with medicine, it's a matter of weighing risk vs. benefit to find the right path for you.
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