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If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.
What is propranolol, and how does it work?
Propranolol (brand name Inderal, InderalXL) is a type of medication known as a beta blocker and is often used to decrease the workload on the heart. Developed in the 1960s, propranolol was the first beta blocker used to treat chest pain from heart disease—this was so revolutionary that the inventor, Sir James Black, won the Nobel prize for his discovery (Srinivasan, 2019). Other examples of beta blockers include atenolol (brand name Tenormin), metoprolol (brand name Lopressor, Toprol XL), Nadolol (brand name Corgard), and Nebivolol (brand name Bystolic).
Your body releases epinephrine (adrenaline)—think “fight or flight”—to increase your heart rate and get more blood pumping. Beta blockers act by stopping epinephrine from binding to beta receptors in your heart muscle—this decreases how hard the heart has to work. Propranolol causes your heart to beat slower and squeeze less forcefully, thereby reducing your heart’s oxygen demand. How propranolol lowers blood pressure is not entirely understood. It is likely a combination of lowering the heart rate and decreasing the kidney’s production of renin (an enzyme that raises blood pressure) (DailyMed, 2019).
What is propranolol used for?
Propranolol is FDA-approved to treat the following conditions (FDA, 2010):
- High blood pressure (hypertension)
- Chest pain (angina pectoris)
- Atrial fibrillation
- Heart attack (myocardial infarction)
- Essential tremor
- Hypertrophic subaortic stenosis
High blood pressure (hypertension)
Approximately half of the adults in the United States have high blood pressure (hypertension), according to the Centers for Disease Control and Prevention (CDC) (CDC-b, 2020). Many do not realize that they have a problem because there are often no symptoms. High blood pressure can not only affect your blood vessels, heart, brain, kidneys, and other body parts, but it can also lead to heart attacks and heart failure.
The good news that you can decrease your risk of strokes and heart attacks by treating your high blood pressure. Your healthcare provider may recommend taking antihypertensives (blood pressure medications) in addition to lifestyle changes like a healthy diet, regular physical activity, and smoking cessation.
Propranolol can help lower blood pressure by decreasing your heart rate and the kidney’s production of renin. However, propranolol is generally not the first medication that your healthcare provider uses for high blood pressure treatment (Lindholm, 2005). Propranolol is often used in combination with different high blood pressure medicines, like diuretics, calcium channel blockers, and angiotensin-converting enzyme (ACE) inhibitors. Sometimes propranolol is combined with one of these other drugs within the same pill—one example is propranolol/hydrochlorothiazide (brand name Inderide).
What is heart disease? What can you do to prevent it?
Chest pain (angina pectoris)
Chest pain, or angina pectoris, is a common sign of coronary heart disease and is often described as pressure or heaviness in your chest; others may feel squeezing or tightness. Chest pain due to coronary heart disease comes from a worsening of atherosclerosis (cholesterol plaques in blood vessel walls). As the plaques get thicker, less blood can get to the heart muscles through the coronary arteries (arteries that feed the heart)—less blood means less oxygen and nutrients to the heart (ischemia).
Angina is your heart’s way of telling you that it is not getting what it needs and may be a precursor to a heart attack (heart cell death). By reducing the heart rate, propranolol can lower how much oxygen the heart needs, thereby improving chest pain. This translates into fewer episodes of chest pain and an improved ability to exercise without angina (DailyMed, 2019).
Atrial fibrillation (also called AFib) is a fast, irregular heartbeat and the most common heart arrhythmia (abnormally fast, slow, or irregular heartbeats) (CDC-a, 2020). According to the AHA, over 2.7 million Americans are living with atrial fibrillation (AHA, 2016). Some people dfescribe atrial fibrillation as having a quivering or fluttery heartbeat; the heart rate can get up to 100–175 beats per minute (normal is 60–100 beats per minute).
This rapid heart rate prevents the heart from completely relaxing and squeezing with each beat, thereby preventing it from filling up with blood—this means that less blood gets pumped to the rest of the body. The blood can pool in the heart because it is not completely squeezing out all the blood, leading to blood clots and other problems like strokes. Atrial fibrillation increases your risk of heart-related deaths and makes you five times more likely to have a stroke if left untreated. (AHA, 2016). Propranolol can help with atrial fibrillation by decreasing the heart rate so that the heart has time to squeeze and relax fully and can effectively pump blood throughout the body.
Heart attack (myocardial infarction)
Every 40 seconds, someone in the U.S. has a heart attack, also called a myocardial infarction (CDC, 2021). The most common cause of heart attacks is coronary artery disease (CAD); CAD is also the leading cause of death in both men and women in the U.S. (NIH, n.d.). Common symptoms of a heart attack include chest pain or tightness, shortness of breath, dizziness, cold sweats, fatigue, nausea, and pain in the jaw, neck, back, or arm.
Coronary artery disease (or coronary heart disease) happens when you have a buildup of fatty deposits (plaque) along the walls of your coronary arteries (the vessels that nourish the heart). This affects blood flow because as the plaque gets thicker, less oxygen-rich blood can flow to the heart muscles—this buildup is called atherosclerosis.
Atherosclerosis may worsen over time, eventually blocking off the vessel entirely. Alternatively, a piece of the plaque can break off and cause a blood clot in the artery. Both of these situations result in a loss of oxygen and nutrients (ischemia) to the area of the heart fed by that coronary artery, and those heart cells start to die—this is a heart attack. Propranolol is often given to people who have survived a heart attack to help the heart stay healthy and decrease mortality.
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Migraines are more than just a bad headache. If untreated, migraine attacks can last anywhere from 4–72 hours and cause moderate to severe pain, usually on one side of the head. Some people have additional symptoms like nausea/vomiting and sensitivity to light and sound. About one-third of people with migraines can predict that one is coming because they see lights, colors, zig-zag lines, or they temporarily lose vision—this is called an “aura” (NINDS-a, 2019).
There is no cure for migraines; one way to treat them is to either relieve the symptoms after an attack has started. The other option is to prevent them from occurring in the first place—this is where propranolol can help. Taking propranolol can decrease the frequency and severity of migraine attacks. While this effect of propranolol is not entirely understood, scientists believe that it is due to the presence of beta receptors on blood vessels in the brain (DailyMed, 2019).
A tremor is an uncontrolled shaking of a part of your body—usually your hands, but it can also affect your head, arms, voice, tongue, legs, and torso. Essential tremor (previously known as benign essential tremor) is a tremor that is not caused by an underlying medical condition (like Parkinson’s disease) or as a side effect of some drugs (like caffeine). It is the most common form of abnormal tremor and is often hereditary—children of someone with essential tremors have a 50% chance of having it themselves (NINDS-b, 2019).
Propranolol can help decrease the amplitude of essential tremors—this means that it makes the shaking motion smaller, but not slower. It is not meant to treat tremors from Parkinson’s disease.
Hypertrophic subaortic stenosis
Hypertrophic subaortic stenosis, now more commonly known as hypertrophic obstructive cardiomyopathy (HOCM), is a heart condition in which the wall (septum) that divides the left and right sides of the heart becomes thickened (hypertrophic). This thickened septum can block the ability of the left ventricle to pump blood into the aorta, the largest artery in the body. HOCM can cause sudden death in young people, often during high-intensity sports. Propranolol and other beta blockers are commonly used in this condition to improve chest pain, shortness of breath with exertion, and to decrease the risk of abnormal heart rhythms (Houston, 2014).
Beta blockers: how they’re used to treat heart conditions
Pheochromocytoma is a tumor that grows in the adrenal glands, small glands that sit on top of your kidneys. Symptoms can be sporadic and intense (called “paroxysmal attacks”) and include high blood pressure, headaches, irregular heartbeats, and sweating. Pheochromocytoma may occur by itself or be a part of other genetic conditions like multiple endocrine neoplasia (MEN2), Von Hippel-Lindau (VHL) syndrome, and neurofibromatosis type 1 (NF1). Propranolol, used along with other medications like alpha blockers, can help reduce the high blood pressure associated with pheochromocytoma.
Propranolol is also prescribed for several “off-label” uses. “Off-label” means that propranolol is being used for conditions other than the ones for which it was officially FDA approved. Some of the off-label uses for propranolol include (UpToDate, n.d.):
- Performance anxiety: If public speaking or performing on stage gives you anxiety, propranolol taken 30–60 minutes before the stressful event may help. It lowers your heart rate, preventing it from racing due to your nervousness. Since your body doesn’t get the anxiety signals from your heart, your anxiety may improve.
- Thyroid storm: Untreated hyperthyroidism can lead to thyroid storm, a rare, life-threatening condition caused by very high levels of thyroid hormones. Symptoms of thyroid storm include very high blood pressure, rapid heart rate, sweating, and agitation. Propranolol can lower the blood pressure and heart rate until the thyroid hormone can be brought back to normal levels.
Infantile hemangioma (children)
Sometimes children develop an abnormal blood vessel growth (hemangioma) under their skin. Propranolol has been shown to help reduce the size of the hemangiomas. It has been FDA-approved for use in infants older than five weeks of age and weighing more than 2 kg for hemangiomas that are spreading and require systemic treatment (FDA, 2014).
Side effects of propranolol
Black box warning from the FDA (the most serious warning they issue): Do not abruptly stop taking propranolol without talking to your healthcare provider. Suddenly stopping propranolol may cause chest pain or heart attack (myocardial infarction). Restart propranolol, even temporarily, if you start to develop chest pain worsens. If you need to stop propranolol, your healthcare provider will help you decrease the dose gradually (FDA, 2010).
Common side effects
Common side effects of propranolol include (Dailymed, 2019):
- Skin rash
- Gastrointestinal problems like nausea, vomiting, diarrhea, or stomach pain
- Depression or other mood changes
- Tingling hands
- Dry eyes
- Breathing difficulties like shortness of breath, wheezing, and cough
- Weight gain: 20.6 pounds of weight gain on average (Sharma, 2001)
- Sexual dysfunction
Insomnia: what is it, symptoms, causes, treatments
Serious side effects
Serious side effects of propranolol include (UpToDate, n.d.):
- Slow heartbeat (bradycardia): One of the ways that propranolol works is by decreasing the heart rate to diminish how hard the heart has to work—so a lower heart rate is expected to some extent. However, if your heart rate drops too low, it can cause fainting spells (syncope), dizziness, chest pains, fatigue, and confusion.
- Low blood pressure (hypotension): Propranolol is often given along with other drugs to help lower blood pressure in people with high blood pressure. In some people, blood pressure can drop too low, leading to dizziness, fainting, blurred vision, fatigue, shallow breathing, rapid pulse, and confusion. Severely low blood pressure is a life-threatening emergency.
- Worsening of lung disease: Propranolol can worsen lung disease, like asthma, emphysema, or chronic obstructive pulmonary disease (COPD), by causing bronchospasm (tightening of the airways). The beta receptors that line the lungs are similar to the ones that propranolol targets in the heart and blood vessels.
- Masking of hypoglycemic symptoms: People with diabetes rely on specific cues to know when their blood sugars drop too low—these signals typically include shakiness, anxiety, confusion, rapid heartbeat (palpitations), lightheadedness, etc. However, propranolol may mask these signs, preventing you from realizing that your blood sugars are too low. If your blood sugars are too low for too long, it can lead to seizures, unconsciousness, and even death in rare cases.
- Decreased blood sugar: Propranolol may reduce blood sugar levels, especially in children and infants, whether or not they have diabetes. This is more likely to happen after not eating for a while (fasting) or after prolonged exercise (DailyMed, 2019).
- Worsening of heart failure: Propranolol increases the risk of worsening heart failure in people with existing heart failure.
- Masking signs of hyperthyroidism: In some people, their thyroid gland makes too much thyroid hormone (hyperthyroidism)—this leads to symptoms like high blood pressure, rapid heart rate, sweating, and agitation. Taking propranolol may mask the appearance of these symptoms, leading to a delay in diagnosis and treatment. Abruptly stopping propranolol can lead to thyroid storm, a potentially life-threatening condition.
- Severe allergic reactions: Serious allergic reactions like hives, swelling, difficulty breathing, or severe skin rashes like Stevens-Johnson syndrome or toxic epidermal necrolysis.
This list does not include all possible side effects and others may exist. Check with your pharmacist or healthcare provider for more information.
Hypoglycemia (low blood sugar) explained
Before starting propranolol, or any new medication, seek medical advice about potential drug interactions. Medicines that may interact with propranolol include (DailyMed, 2019):
- Drugs that affect the cytochrome P-450 system: The P-450 system breaks down propranolol in the liver. Drugs that affect this system can change the concentrations of propranolol in your body, leading to dose adjustments. Medications like cimetidine, fluoxetine (brand name Prozac; see Important Safety Information), and fluconazole inhibit the P-450 system causing higher than expected levels of propranolol levels. Other drugs, like rifampin, phenytoin, and phenobarbital, increase the metabolism of propranolol and result in lower than anticipated levels of propranolol. Cigarette smoking also affects the liver’s system and makes propranolol less effective.
- Drugs that affect heart rhythm: Combining these medications with propranolol increases the risk of side effects; examples include amiodarone, propafenone, quinine, digoxin, and lidocaine.
- Calcium channel blockers: Taking propranolol with certain calcium channel blockers increases the risks of side effects, like a slow heart rate or low blood pressure; examples include nisoldipine, nicardipine, and nifedipine, verapamil, and diltiazem.
- Other medications that lower blood pressure: Combining blood pressure medicines like angiotensin-converting enzyme (ACE) inhibitors or alpha blockers with propranolol can cause your blood pressure to drop too low. Examples of these medications include lisinopril, enalapril, prazosin, terazosin, and doxazosin.
- Migraine medications: Using the migraine medications zolmitriptan or rizatriptan with propranolol increases the concentrations of both zolmitriptan and rizatriptan.
- Diazepam: Diazepam (brand name Valium) is sometimes used to treat anxiety symptoms. However, combining it with propranolol increases the levels of diazepam in the body and raises the risk of side effects.
- High cholesterol medications: Certain drugs used to lower cholesterol, like cholestyramine and colestipol, lower the effective concentration of propranolol in your system. Others, like lovastatin or pravastatin, have reduced levels when combined with propranolol.
- Non-steroidal anti-inflammatory drugs (NSAIDs): NSAIDs help with pain and inflammation. However, they can decrease the effectiveness of propranolol; examples of NSAIDs include indomethacin and ibuprofen.
- Monoamine oxidase inhibitors (MAOIs): Often used to treat depression, MAOIs may increase the risk of side effects if taken with propranolol. Examples include isocarboxazid, phenelzine, selegiline, and tranylcypromine.
- Warfarin: Warfarin is a commonly used blood thinner and needs to be maintained within precise levels to be both safe and effective. Combining warfarin with propranolol can result in an increased concentration of warfarin.
- Alcohol: Alcohol can raise your propranolol levels, increasing your risk of side effects.
This list does not include all possible drug interactions with propranolol, and others may exist. Check with your pharmacist or healthcare provider for more information.
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Who should not take propranolol (or use it with caution)
Certain groups of people should avoid using propranolol or use it with caution (UpToDate, n.d.):
- Pregnant women: The U.S. Food and Drug Administration (FDA) has deemed propranolol as pregnancy category C; this means that there is not enough information to determine the risk to the pregnancy (FDA, 2010).
- Nursing mothers: Propranolol gets into breastmilk; women and their healthcare providers should use caution with propranolol (FDA, 2010).
- People with lung problems: Propranolol can cause worsening of asthma, emphysema, or COPD, and people with these conditions should avoid using it.
- People with diabetes: Propranolol can block the signs of low blood sugar levels.
- People with a slow heart rate (bradycardia) or low blood pressure (hypotension): Propranolol lowers both blood pressure and heart rate.
- People with heart failure: Propranolol can worsen heart failure and should be used with caution if you have this condition.
- People with liver disease: The liver breaks down propranolol, and if you have liver disease, you may need a dose adjustment.
- People with kidney disease: Use propranolol with caution if you have kidney problems as you may need a dose adjustment.
- People with myasthenia gravis: Myasthenia gravis is a disease that affects your nerves and muscles. Taking propranolol sometimes worsens the symptoms of myasthenia, so use it with caution if you have this condition.
- Peripheral vascular disease and Raynaud disease: People with peripheral vascular disease or Reynaud disease have circulation problems, especially to their extremities. Propranolol may make their symptoms worse, so it should be used with caution.
This list does not include all possible at-risk groups, and others may exist. Seek medical advice from your healthcare provider or pharmacist for more information.
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Propranolol hydrochloride (brand name Inderal) is available in immediate-release, extended-release, and intravenous injection formulations, as well as oral solutions for those who cannot tolerate swallowing medications. The immediate-release pills come in 10 mg, 20 mg, 40 mg, 60 mg, and 80 mg strengths and are usually taken 2–4 times per day. The extended-release version only has to be taken once a day and comes in 60 mg, 80 mg, 120 mg, and 160 mg strengths. A specific oral solution, brand name Hemageol, is used only for children with infantile hemangioma and comes in a 4.28 mg/mL solution.
Most prescription plans cover propranolol, and the cost for a 30-day supply ranges from $7–$37 depending on the form and strength.
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- National Institute of Neurological Disorders and Stroke (NINDS-a). (2019). Migraine Information Page. Retrieved on Sep. 10, 2020 from https://www.ninds.nih.gov/health-information/disorders/migraine
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- U. S. Food and Drug Administration (FDA). (2010). Inderal (propranolol hydrochloride) tablets. Retrieved on Sep. 10, 2020 from https://www.accessdata.fda.gov/drugsatfda_docs/label/2011/016418s080,016762s017,017683s008lbl.pdf
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Dr. Mike is a licensed physician and the Director, Medical Content & Education at Ro.