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Beta blockers, or beta-adrenergic blocking agents, are a class of medications that decrease the strain on the heart. They are used to prevent, treat, or improve symptoms in the following conditions:
- Abnormal heart rhythms (arrhythmias) like atrial fibrillation and tachycardia
- Congestive heart failure
- Chest pain (angina)
- Heart attacks (myocardial infarctions)
- High blood pressure (hypertension)
Beta blockers work by stopping the “fight or flight” hormones, like epinephrine (also known as adrenaline), from binding to beta receptors in your heart muscle, blood vessels, kidneys, and other places in the body. By blocking these receptors, these drugs can decrease how much your heart has to work to pump blood around the body. There are several different beta-blockers available, and they all work via slightly different mechanisms. However, the overall effect is the same: they cause your heart to beat slower and squeeze less forcefully, thereby lowering blood pressure. Some beta blockers also help relax (or dilate) your blood vessels to improve blood flow. The overall effect is that your heart does not have to work as hard (this is good in cases like a heart attack, during which it is best to decrease the amount of oxygen the heart needs).
Even though beta blockers decrease your blood pressure, they are generally not the first medication that your healthcare provider will turn to for high blood pressure treatment (Schumann, 2008). However, beta blockers are often used in combination with other medicines, like diuretics, calcium-channel blockers, and angiotensin-converting enzyme (ACE) inhibitors, especially if your high blood pressure is not improved with one drug alone. In addition, beta blockers are less effective when used as a single agent for treating high blood pressure in black individuals and those older than 60 years old (Schumann, 2008).
Common beta blockers include:
- Acebutolol (brand name Sectral)
- Atenolol (brand name Tenormin)
- Bisoprolol (brand name Zebeta)
- Carvedilol (brand name Coreg)
- Metoprolol (brand names Lopressor, Toprol XL)
- Nadolol (brand name Corgard)
- Nebivolol (brand name Bystolic)
- Propranolol (brand names Inderal, InnoPran XL)
- Timolol (brand name Timoptic)
Propranolol is one of the few beta blockers that is FDA approved to treat non-cardiac conditions. It is the only beta blocker approved to treat essential tremor, which is a chronic nervous system disorder that causes shaking. Propranolol is also FDA approved to treat migraine headaches. However, there are “off-label” uses of propranolol as well. “Off-label” means that the drug is being used for conditions other than the ones for which it was officially FDA approved. These “off-label” uses include the treatment of performance anxiety, such as before giving a big speech or a music performance.
Potential side effects of beta blockers
As with any medication, there is always the potential for side effects. In beta blockers, these include:
- Cold hands or feet
- Weight gain
- Gastrointestinal problems like nausea, vomiting, diarrhea, or stomach cramps
- Shortness of breath
- Trouble sleeping
- Sexual dysfunction
- Inability to tell if you have low blood sugar (hypoglycemia unawareness)
People who have used some of the older beta blockers, like atenolol and metoprolol, have reported a weight gain of an average of 2.6 pounds (Sharma, 2001). Newer beta blockers, like carvedilol, do not seem to have this effect; the reason behind this is not well understood. It could be that the beta blocker is slowing down your metabolism, or you could be retaining water weight. It is important to emphasize that if you are taking a beta blocker for heart failure, a weight gain of more than 2-3 pounds can be a sign of fluid buildup in your body from worsening heart failure; inform your provider right away.
If you are experiencing any of these symptoms, talk to your healthcare provider. Do not abruptly stop taking a beta blocker without your provider’s approval because doing so can increase your risk of chest pain, heart attacks, or other heart problems. Lastly, let your provider know if you are taking any other medications or supplements to ensure that you don’t have any adverse drug interactions.
Who should avoid taking beta blockers?
In general, the following groups should avoid beta blockers or use them with caution:
- People with asthma: Beta blockers may trigger a severe asthma attack. This is due to the fact that the airways in your lungs are also lined with beta receptors. Without getting too much into the details, there are essentially two types of beta receptors: B1 receptors in the heart and B2 receptors in the lungs. These B2 receptors are responsible for opening up your airway to help you breathe better. As a result, if you have asthma and take a beta blocker that binds to both B1 and B2 receptors, it can cause your airways to close up and trigger an asthma attack. Make sure your provider is aware that you have asthma; there are beta blockers that only bind to the heart’s B1 receptors and are safer for people with asthma.
- Diabetics: Beta blockers can block the signs of low blood sugar, like increased heart rate, sweating, and tremors.
- Slow heart rate (bradycardia) or low blood pressure (hypotension): Beta blockers lower blood pressure and heart rate.
- People who are taking sildenafil (brand name Viagra) or other phosphdiesterase (PDE) inhibitors: Make sure to tell your healthcare provider before starting a beta-blocker that you are also taking erectile dysfunction medications like sildenafil (brand name Viagra; see Important Safety Information). There are some beta-blockers (like carvedilol and labetalol) that can cause a significant drop in blood pressure if taken with PDE inhibitors. Let your provider know to avoid any potentially dangerous side effects.
Beta blockers are widely used and generally well tolerated. Make sure that you discuss your medical conditions and treatment options with your healthcare provider so that you understand what conditions the beta blockers are treating and what effects to expect while taking these medications. Talk to your provider before stopping or changing the dose of these drugs.
- Schumann, S. A. & Hickner, J. (2008). When not to use beta-blockers in seniors with hypertension. The Journal of Family Practice, 57(1), 18–21. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3183837/
- Sharma, A. M., Pischon, T., Hardt, S., Kunz, I., & Luft, F. C. (2001). Hypothesis:β-Adrenergic Receptor Blockers and Weight Gain. Hypertension, 37(2), 250–254. doi: 10.1161/01.hyp.37.2.250. Retrieved from https://www.ahajournals.org/doi/full/10.1161/01.hyp.37.2.250
Dr. Mike is a licensed physician and the Director, Medical Content & Education at Ro.