Doctors typically prescribe propranolol for heart-related issues, but it can also relieve the physical symptoms of anxiety, such as shaking and sweating. The effects are most noticeable between 1 and 4 hours after taking a dose.

Propranolol, which is available as a generic drug and under the brand name Inderal, is a type of beta-blocker. Beta-blockers work by blocking the heart’s receptors for epinephrine. Doctors may also prescribe it to treat migraine and essential tremor.

Epinephrine acts as a stimulant for the heart, causing it to beat harder and faster. By blocking epinephrine, propranolol helps relax the heart. In some cases, it can also help relax the blood vessels.

In the 1960s, researchers found that propranolol has an antianxiety effect in people. Doctors have since prescribed it off-label to treat anxiety. Off-label means that the prescribed medication is not specifically intended for that use and does not have current approval from the Food and Drug Administration (FDA) for that use.

Propranolol does not treat the underlying psychological causes of anxiety. Instead, it may help with some of the physical symptoms that anxiety can cause. These can include:

  • rapid heartbeat
  • sweating
  • feeling dizzy
  • shaky hands or voice

A 2016 review found that for short-term use, it was just as effective in treating panic disorders as benzodiazepines, which include Xanax (alprazolam), Klonopin (clonazepam), and Ativan (lorazepam). However, despite this, the authors conclude that there is insufficient evidence to support the use of propranolol for the treatment of any anxiety disorders.

If a doctor does prescribe propranolol for anxiety, it typically starts to work relatively quickly to alleviate the physical symptoms of anxiety.

This article reviews how quickly propranolol works for anxiety and provides other information about the time frames surrounding its use.

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Doctors may prescribe propranolol off-label to help with the physical symptoms of anxiety or stage fright. Athletes and other performers may also benefit from using propranolol, although its use is not permitted in certain sports and competitions.

When people take propranolol for anxiety symptoms, it should start to work within an hour.

Propranolol has a half-life of about 4 hours, which means that the effects will likely start to fade about 4 hours after taking a dose.

An extended-release version of the drug is also available, which will take longer to start working but remain effective for longer. However, doctors do not generally prescribe this form of the drug for anxiety.

Propranolol has a 4-hour half-life. Its concentration in the blood is highest between 1 and 4 hours after taking a dose.

Depending on the person’s need, a doctor may recommend taking a dose three or four times a day to maintain the effects of the medication. Some people may only need to take it shortly before a stressful event, such as a performance or speech.

The best time to take propranolol will vary depending on the person’s needs and any other medications they take.

Evidence suggests that taking propranolol with protein-rich foods increases its bioavailability in the blood by 50%.

A doctor will provide instructions on when a person should take propranolol for their anxiety symptoms. They may recommend daily dosing or only taking it on an as-necessary basis.

In either case, a person should follow the recommended dosage and only take it according to their prescription. They should also continue with other therapies for their anxiety, which may include psychotherapy, other medications, or certain lifestyle adjustments.

Propranolol is relatively safe for most people, meaning that someone should be able to take it for as long as necessary or for the duration their doctor prescribes.

It is important to note that propranolol does not treat the underlying causes of anxiety. A person will need additional therapies to treat anxiety and may only need propranolol on an ad-hoc basis or for a short period.

Other treatments that can effectively treat anxiety include:

Propranolol is relatively safe to take, but it can cause side effects in some people. Possible side effects include:

  • gastrointestinal problems, such as nausea and diarrhea
  • rashes and other skin reactions
  • erectile dysfunction
  • a slow heart rate when stopping the medication
  • low blood pressure
  • an increased risk of anesthesia complications

A person should talk with their prescribing doctor about any medications they are taking. The doctor can determine whether propranolol may interact with these other medications and make any necessary changes to the prescription.

Propranolol may help with the physical symptoms of anxiety. It is relatively fast-acting and should be most effective for the first 4 hours.

A doctor may prescribe it for daily use or recommend using it as and when a person feels the need. A person should review all their medications with the doctor and take propranolol according to their prescription.