10 Propranolol Side Effects You Should Know About

Propranolol (Inderal LA, Innopran XL) is a beta blocker medication with many uses. Like other beta blockers, propranolol helps treat heart-related conditions such as heart failure and high blood pressure. But propranolol can also help prevent migraines and manage tremors. It’s even prescribed off-label for performance anxiety. But no matter why you’re taking propranolol, it's helpful to be aware of the possible side effects you may experience.

Propranolol side effects at a glance

Below is a list of common and serious propranolol side effects reported in clinical studies. Keep in mind that this list doesn’t cover every possible issue. So it’s best to contact your healthcare team if you have questions or concerns about side effects while taking propranolol.

Common propranolol side effects:

• Dizziness

• Fatigue and weakness

• Nausea

• Stomach pain

• Diarrhea or constipation

• Low blood pressure

• Slow heart rate

• Sexual problems, such as erectile dysfunction (ED)

• Trouble sleeping

• Vivid dreams nightmares

• Depressed mood

Serious propranolol side effects:

• Masking the symptoms of low blood glucose (hypoglycemia)

• Hallucinations

• Rapid weight gain or fluid retention

• Worsening heart problems

• Heart block

• Breathing problems

• Severe skin reactions

• Withdrawal symptoms if stopped abruptly (including heart attack)

Below we’ll delve deeper into 10 notable propranolol side effects.

1. Low blood pressure

Beta blockers such as propranolol can lower your blood pressure. This is helpful if you’re taking it to help treat high blood pressure. But if your blood pressure drops too low (hypotension), you may feel dizzy or lightheaded.

Low blood pressure symptoms will often go away after a few days as your body gets used to propranolol. In the meantime, use caution when driving or performing activities that require coordination to avoid accidents. And take your time when changing positions, such as sitting up or standing. It’s also best to avoid alcohol while you’re taking propranolol, as it can worsen this side effect.

If your symptoms don’t improve, let your prescriber know. They may need to adjust your propranolol dosage to keep your blood pressure from dropping lower than it should.

Good to know: Don’t stop taking propranolol on your own, even if side effects are bothersome. Stopping it abruptly could cause serious heart problems. Your prescriber can help you stop taking propranolol safely, if needed.

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2. Slow heart rate

A slow heart rate (under 60 beats per minute) is another propranolol side effect. Often, this is an intended effect of the medication and may not cause noticeable symptoms. But in some cases, it can make you feel tired or dizzy. And it can make certain activities feel harder, such as walking up stairs or exercising.

Side effects from a lower heart rate may improve over time as your body gets used to propranolol. But if it’s bothersome or worsens, let your prescriber know.

It isn’t common, but sometimes propranolol can slow your heart so much that it can’t pump properly (heart block). Symptoms of heart block include chest pain, trouble breathing, and feeling dizzy. You may also feel your heart skip a beat or beat strangely. If this happens, seek medical care right away.

3. Dizziness

Dizziness is a common propranolol side effect of propranolol. It’s often linked to changes in blood pressure or heart rate, and it often improves after a few days. Taking propranolol at bedtime can help lessen daytime dizziness. But check with your prescriber first to make sure this is a safe option for you.

If you’re feeling dizzy, it’s best to avoid activities that require coordination, such as driving. If dizziness becomes a problem or doesn’t go away, talk to your prescriber about next steps.

4. Fatigue

Like other beta blockers, propranolol can cause fatigue. You may feel weaker or more tired than usual. This might be caused by a slower heart rate or lower blood pressure, as mentioned above.

In some cases, fatigue can last for several weeks after starting propranolol before your body adjusts. So it may help to avoid strenuous activities until you’re feeling more like yourself. And you can help keep your energy levels up by staying hydrated, eating a heart-healthy diet, and getting enough sleep. But if your fatigue becomes bothersome or isn’t going away, talk to your prescriber about what to do next.

5. Nausea

Nausea is another possible propranolol side effect that’s common for all beta blockers. There are a few things you can try to help prevent and manage nausea. These include eating smaller meals, drinking plenty of water, and avoiding spicy or fried foods that can worsen nausea. Taking propranolol with food may also help.

Talk to your healthcare team if nausea is a problem for you. They help determine the cause and take steps to manage it.

6. Sleep issues

Beta blockers are known to cause vivid dreams or nightmares. And propranolol seems to be more likely to cause this side effect than some other beta blockers. It can also cause you to have trouble sleeping (insomnia).

Experts think that one reason beta blockers cause sleep issues is that they block the effects of melatonin. Melatonin is a natural hormone that helps regulate sleep. So a melatonin supplement may help lessen this side effect, if your prescriber OKs it.

If you’re unable to get adequate rest while taking propranolol, let your prescriber know. They may switch you to a different beta blocker that’s less likely to cause sleep issues.

7. Mood changes

Some people report a depressed mood while taking propranolol. This could be related to sleep issues and fatigue caused by the medication. It’s also worth noting that propranolol is often prescribed for health conditions that can also contribute to depression. So it’s hard to know whether this is a side effect of propranolol or the condition it’s treating.

Still, if you notice a change in your mood while taking propranolol it's best to let your healthcare team know. They can make changes to your medication or suggest other options to help support your mental well-being.

If you or a loved one are struggling with depression, help is available. Call SAMHSA’s National Helpline at 1-800-662-4357. For immediate assistance, call the National Suicide Prevention Lifeline at 988, or text HOME to 741-741 to reach the Crisis Text Line.

8. Masking low blood glucose symptoms

Propranolol can mask several symptoms of low blood glucose (sugar), such as a fast heart rate, tremor, and anxiety. Low blood glucose (hypoglycemia) can be a problem for anyone, but it’s especially dangerous if you’re living with diabetes. So it’s helpful to be aware that it may be harder to realize your blood glucose is low if you’re taking propranolol.

One symptom that propranolol doesn’t affect is sweating. So if you start to feel sweaty or clammy, it’s a good idea to check your blood glucose level and treat it promptly if your level is low.

9. Erectile dysfunction

Erectile dysfunction (ED) is a common side effect of beta blockers, and propranolol is no exception. Beta blockers are thought to contribute to ED because of reduced blood flow to the penis.

This may be embarrassing to bring up, but rest assured that it’s best to let your prescriber know if propranolol is causing bothersome sexual side effects. They can prescribe an ED treatment to help, or they may help you find an alternative to propranolol that’s less likely to cause this side effect.

10. Breathing problems

Propranolol is a non-selective beta blocker. This means it affects receptors (binding sites) in areas other than your heart. This may not cause issues for you. But if you’re living with asthma or a similar lung condition, propranolol may make it harder for you to breathe. This is because it affects binding sites in the lungs that can constrict your airways.

If you have a lung condition, a selective beta blocker is generally a better option, since these only affect the heart. So be sure to let your prescriber know your medical history before you start taking propranolol. And if you feel that propranolol is affecting your breathing (even if you don’t have a lung condition) contact your prescriber. They can recommend next steps, which might include gradually stopping propranolol or switching to a different medication.