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Propranolol 101: How it Works, Uses, Side Effects and More

Dr. Patrick Carroll, MD
Medically reviewed by Patrick Carroll, MD Written by Our Editorial Team Last updated 4/03/2020

Propranolol is a beta blocker medication that’s used to treat heart problems and anxiety. Like other beta blockers, it works by relaxing blood vessels and lowering your heart rate, and subsequently reducing the physical effects of anxiety.

As one of the earliest and most widely prescribed beta blockers, propranolol is used by millions of people in the United States alone.

Below, we’ve explained how propranolol works as a medication, as well as what it’s commonly used for. We’ve also covered the side effects of propranolol, potential propranolol interactions and tips for using it safely and effectively.

How Does Propranolol Work?

Propranolol is a beta blocker. It works by blocking the action of stress hormones like adrenaline (epinephrine) and noradrenaline (norepinephrine) on your body’s beta receptors.

Adrenaline and noradrenaline are hormones used to signal the fight-or-flight response. If you’re in a stressful or dangerous situation, your body starts to secrete higher levels of these hormones, triggering your fight-or-flight response and causing your heart rate to suddenly increase.

Stress hormones like adrenaline and noradrenaline can also make you feel anxious, shaky and sweaty. In short, they’re the hormones that trigger nervousness and encourage you to make a decision in tense situations.

Fight-or-flight is a survival mechanism designed to protect you when you’re in danger. However, if you have an anxiety disorder, it can affect you in other situations, such as performing in front of other people, meeting someone new or making small talk with a friend or stranger.

By stopping adrenaline and noradrenaline from affecting your body’s beta receptors, propranolol can block the physical effects of anxiety. This means you won’t notice a faster heartbeat, sweaty hands or shaking when you’re in an environment that triggers feelings of fear or anxiety.

Instead, your heartbeat will slow down slightly and you’ll feel more relaxed, making it easier for you to function normally if you’re prone to anxiety.

Propranolol is not the same as anti-anxiety drugs like Xanax® or Valium®. Instead of targeting the brain, it works by affecting the way you physically respond to anxiety-producing hormones.

What is Propranolol Used For?

Propranolol is one of the oldest beta blocker medications. It was first discovered in the 1960s  and was originally designed to treat heart conditions such as chest pain and to increase survival after a heart attack.

Today, propranolol is still widely used as a treatment for these and other heart conditions (such as managing hypertension and heart rhythm problems. It’s also used to treat anxiety, migraines, tremors, effects of hyperthyroidism, aggressive behavior after brain injuries, post-traumatic stress disorder and can also be used on a short-term basis to treat the effects of phobias

Propranolol is one of the most widely used and effective medications available for performance anxiety. It’s used by musicians and other people who need to perform in front of others, many of whom are naturally affected by anxiety.  

In addition to heart conditions and performance anxiety, propranolol is a common treatment for migraine headaches that don’t respond to conventional pain management drugs.

How Do You Take Propranolol?

Propranolol is a prescription drug, meaning you’ll need to talk to your doctor before you can buy and use it. It’s available in four different forms:

  • As a tablet. Propranolol is widely sold as an oral tablet. It’s a generic drug, meaning it’s usually sold simply as “propranolol” without a brand name. The propranolol oral tablet is the most common form of this medication and can last for up to 12 hours at a time.
  • As an extended-release capsule. The extended-release version of propranolol lasts for longer than the oral tablet.
  • As an oral liquid solution. The oral liquid version of propranolol has the same effects as the oral capsule.
  • As an injection. This version of propranolol is designed for IV injection and is typically only used in a medical setting.

If you have an anxiety disorder, you’ll usually be prescribed propranolol as an oral tablet. This form of propranolol is easy and convenient to use, with a variety of strengths available to suit your needs.

Does Propranolol Have Side Effects?

Propranolol is a safe, effective medication that has been used for decades to treat heart issues, anxiety and other conditions. Side effects are typically mild and uncommon but can still affect you, especially after you first begin using the medication. Common propranolol side effects include:

  • Slower-than-normal heart rate. Because propranolol blocks the effects of adrenaline on your heart, it can give you a lower-than-normal heart rate. It’s completely normal to experience a lower heart rate after you take propranolol. However, if your resting daytime heart rate drops below 50 beats per minute while using propranolol, you should contact your doctor as soon as possible.

  • Sleep problems. There are reports of  insomnia, awakenings at night and other sleep problems while taking propranolol for hypertension. Several beta blockers are also linked to vivid and unusual dreams.
  • Fatigue. Propranolol can make you feel more tired than normal due to its effects on the way your body responds to stress hormones. This is most common after you first start to use the medication and usually stops occurring after several days or weeks.
  • Diarrhea. Somepeople who use propranolol might experience diarrhea shortly after taking the medication. Propranolol can also cause nausea, especially in the first few weeks of treatment.

  • Hair loss. Propranolol is one of several beta blockers that can cause hair loss. The hair loss from propranolol is not permanent, and is typically a result of the medication causing some hair follicles to enter their shedding phase prematurely.

  • Dry eye syndrome. Propranolol and other beta blockers can cause you to develop dry eyes, potentially resulting in eye irritation.

Propranolol is generally safe and side effects are usually mild and can be managed. If you experience any of the above side effects from propranolol, it’s best to contact your doctor. Many of these effects can be reduced or avoided by adjusting your propranolol dosage or switching beta blockers.

Propranolol also has the potential for several serious potential side effects. These are rare and only affect a tiny percentage of users. However, if you experience any of the side effects listed below, or experience an allergic reaction to propranolol, you should seek help from your doctor as soon as possible:

  • Noticeably cold hands and/or feet
  • Low blood sugar
  • Persistent insomnia or nightmares
  • Hallucinations
  • Difficulty breathing
  • Resting heart rate below 50 beats per minute
  • Rapid weight gain and/or fluid retention in the legs and ankles
  • Severe nausea, diarrhea or vomiting

Signs of an allergic reaction to propranolol include rash, wheezing, chest or throat tightness, trouble breathing or talking, and facial, lip, mouth or throat swelling. 

For more on propranolol’s complete list of side effects, head on over to our Complete Guide to Propranolol Side Effects.

Can Propranolol Interact With Other Medications?

Yes. Unfortunately, propranolol interactions do occur with a variety of other medications. Some of these interactions are listed below.

Major propranolol interactions can occur with antiarrhythmic drugs (which are used to treat heart rhythm problems) and hypertension drugs, such as calcium channel blockers, alpha blockers and angiotensin converting enzyme (ACE) inhibitors.

Propranolol can also interact with other beta blockers, meaning you should never take it with drugs such as acebutolol, atenolol, bisoprolol, carteolol, esmolol, metoprolol, nadolol, nebivolol or sotalol. Used with propranolol, these drugs can cause a dangerous drop in your heart rate.

Propranolol should not be used with lisinopril or enalapril (both ACE inhibitors), with diltiazem (a calcium channel blocker), or with prazosin, terazosin or doxazosin (all alpha blockers). Propranolol interactions may also occur with certain asthma medications, such as theophylline or any NSAIDs.

Due to its effects on heart rate and blood pressure, propranolol is not recommended for use with any stimulants, such as epinephrine, isoproterenol or dobutamine. Propranolol can also interact with some blood thinners, such as warfarin, causing an increase in warfarin concentration.

Your doctor might also recommend avoiding common stimulants such as caffeine, as these can affect the effectiveness of propranolol. Propranolol can also affect your body’s ability to process high-potassium foods.

Since propranolol is a prescription drug, you’ll need to talk to your doctor before you’re able to use it. Make sure you inform your healthcare provider of all medications you use on a regular basis to avoid any potential interactions.

Is it Safe to Take Propranolol With Alcohol?

Propranolol should not be used with alcohol. One study found that consuming alcohol while you’re under the effects of propranolol can increase the blood pressure lowering effects  of propranolol, causing you to feel lightheaded and sleepy.

Is it Safe to Exercise After Taking Propranolol?

Like other beta blockers, propranolol can reduce your heart rate. This means that you may have a lower-than-normal heart rate while exercising and this can make it harder to exert yourself. Most of the time, it’s okay to exercise at a mild to moderate intensity level while on propranolol.

However, if you engage in strenuous exercise, or frequently work out until you’re exhausted, you should talk to your doctor before using propranolol or any other beta blockers.

Learn More About Beta Blockers

Propranolol is one of several beta blocker medications used to treat heart conditions, anxiety, migraines and other conditions. Our guide to beta blockers goes into more detail on how beta blockers work, as well as other, non-propranolol drugs in this class.

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.