Propranolol side effects: what you need to know

Propranolol is a non-selective beta-blocker widely prescribed for anxiety, migraine prevention, essential tremor and cardiovascular conditions.

Its side effects reflect its pharmacological action of blocking beta-1 and beta-2 adrenergic receptors throughout the body.

Very common and common side effects:

• Fatigue and tiredness: one of the most frequently reported effects, caused by reduced cardiac output and lower blood pressure. Many patients describe feeling generally less energetic
• Cold extremities: cold hands and feet are characteristic of beta-blockers, caused by peripheral vasoconstriction when beta-2 receptors in blood vessels are blocked. This affects approximately 10 to 15% of patients
• Dizziness and lightheadedness: related to blood pressure lowering, especially when standing up quickly (postural hypotension)
• Bradycardia: a slow heart rate (below 60 beats per minute) is expected with beta-blockers. This is usually asymptomatic but can occasionally cause dizziness or faintness
• Sleep disturbance: propranolol crosses the blood-brain barrier readily, which can cause vivid dreams, nightmares or insomnia in some patients
• Nausea and gastrointestinal upset: usually mild and transient
• Dry eyes: relevant for contact lens wearers

The BNF lists these as recognised effects of non-selective beta-blockers. They are generally dose-dependent and tend to be most noticeable in the first few weeks of treatment.

While uncommon, propranolol can cause serious side effects that require prompt medical attention.

Bronchospasm:

Propranolol blocks beta-2 receptors in the lungs, which can cause narrowing of the airways. This is the reason propranolol is contraindicated in asthma.

Even patients without a formal asthma diagnosis who have a history of wheezing should avoid non-selective beta-blockers. Symptoms include shortness of breath, wheezing and chest tightness.

Seek emergency help if these occur.

Severe bradycardia and heart block:

Excessive slowing of the heart rate can cause:

• Fainting or near-fainting episodes
• Severe dizziness
• Profound fatigue

This is more likely at higher doses or when combined with other medicines that slow the heart, such as diltiazem, verapamil or digoxin.

Hypoglycaemia masking:

Propranolol can mask the warning signs of low blood sugar (tremor, palpitations, sweating), which is particularly important for patients with diabetes on insulin or sulphonylureas.

The BNF advises caution with beta-blockers in diabetes.

Severe hypotension:

A significant drop in blood pressure may cause fainting, especially in patients already on other antihypertensive medicines.

Worsening of peripheral vascular disease:

Propranolol can worsen symptoms of Raynaud's phenomenon or intermittent claudication due to peripheral vasoconstriction.

Do not stop propranolol abruptly, as this can cause rebound tachycardia, hypertension and, in patients with ischaemic heart disease, angina or even myocardial infarction.

Because propranolol crosses the blood-brain barrier more readily than many beta-blockers, it can cause central nervous system effects.

Sleep disturbance:

• Vivid dreams and nightmares are reported by approximately 5 to 10% of patients
• Insomnia or disrupted sleep patterns may occur
• These effects are more common with propranolol than with more hydrophilic beta-blockers such as atenolol
• Taking the last dose of the day in the late afternoon rather than at bedtime may help

Mood changes:

• Low mood or depression: there has been long-standing debate about whether beta-blockers cause depression. Current evidence suggests the risk is small but real, particularly with lipophilic agents like propranolol
• Lethargy and reduced motivation: some patients describe a general dampening of emotional responsiveness
• Paradoxically, for patients taking propranolol for anxiety, the overall effect on mood is usually positive

Cognitive effects:

• Some patients report difficulty concentrating or mild memory difficulties
• These effects are typically subtle and dose-dependent

Sexual dysfunction:

• Erectile dysfunction has been reported with beta-blockers, including propranolol
• The mechanism may involve reduced blood flow and altered sympathetic nervous system activity
• This is an important consideration that should be discussed openly with your prescriber

If psychological or neurological side effects are troublesome, your prescriber may consider switching to a cardioselective beta-blocker (e.g. bisoprolol) or a water-soluble beta-blocker (e.g.

atenolol) that crosses the blood-brain barrier less readily.

Many propranolol side effects can be minimised with practical strategies and dose adjustments.

Cold hands and feet:

• Wear warm gloves and thick socks, especially in cold weather
• Regular exercise can help improve peripheral circulation
• Avoid smoking, which worsens peripheral vasoconstriction
• If severe, your prescriber may switch to a cardioselective beta-blocker

Fatigue:

• Take propranolol at a time when tiredness is least disruptive (e.g. evening dose)
• Stay physically active, as regular exercise can counteract lethargy
• Ensure adequate sleep and hydration
• If fatigue is severe, a dose reduction may be appropriate

Dizziness:

• Stand up slowly from sitting or lying positions
• Avoid prolonged standing in hot environments
• Stay well hydrated
• Report frequent dizziness to your prescriber, as the dose may need adjusting

Sleep problems:

• Take the last dose at least 4 to 6 hours before bedtime
• Maintain good sleep hygiene: regular schedule, dark room, avoiding screens before bed
• If nightmares persist, discuss timing changes or alternative medicines

General advice:

• Never stop propranolol suddenly. Always reduce the dose gradually over 1 to 2 weeks under medical supervision
• Attend regular reviews, especially in the first few months of treatment
• Keep a symptom diary to discuss at appointments

Certain conditions and circumstances make propranolol unsuitable or require extra caution.

Absolute contraindications (do not take):

• Asthma or history of bronchospasm: non-selective beta-blockers can trigger life-threatening airway narrowing
• Uncontrolled heart failure: propranolol can worsen acute heart failure by reducing cardiac output
• Severe bradycardia: a resting heart rate below 50 bpm is generally a contraindication
• Second or third-degree heart block: unless a pacemaker is in place
• Prinzmetal's angina: variant angina caused by coronary artery spasm
• Phaeochromocytoma (unless alpha-blocked first)

Relative contraindications (use with caution):

• Diabetes: propranolol masks hypoglycaemia symptoms and can prolong recovery from low blood sugar
• Peripheral vascular disease: may worsen claudication or Raynaud's phenomenon
• COPD without reversible airways disease: cardioselective beta-blockers are preferred
• First-degree heart block: monitor ECG
• Liver impairment: propranolol is extensively metabolised by the liver, and doses may need reduction
• Myasthenia gravis: beta-blockers may worsen muscle weakness

Pregnancy and breastfeeding:

• Propranolol can be used in pregnancy when the benefit outweighs the risk, but the baby should be monitored for bradycardia and hypoglycaemia after birth
• It passes into breast milk in small amounts; specialist advice should be sought

The BNF provides detailed contraindication and caution listings for all beta-blockers.

Propranolol is one of many beta-blockers available in the UK. Its non-selective nature and lipophilic properties distinguish it from alternatives.

Propranolol versus bisoprolol:

• Bisoprolol is cardioselective (beta-1 selective), meaning it has less effect on the lungs and peripheral blood vessels
• Bisoprolol is preferred for patients with COPD or mild peripheral vascular disease
• Bisoprolol is first-line for heart failure (propranolol is not licensed for this)
• Propranolol is preferred for anxiety and tremor because it blocks peripheral beta-2 receptors that mediate these symptoms

Propranolol versus atenolol:

• Atenolol is cardioselective and water-soluble, crossing the blood-brain barrier less readily
• Atenolol causes fewer sleep disturbances and nightmares than propranolol
• Propranolol is generally more effective for performance anxiety and physical symptoms of anxiety

Why propranolol is chosen for anxiety:

The physical symptoms of anxiety (tremor, palpitations, sweating, shaky voice) are mediated by peripheral beta-2 receptors and circulating adrenaline.

Propranolol's non-selective beta-blockade is particularly effective at dampening these symptoms, which is why it is the most commonly prescribed beta-blocker for anxiety and situational performance anxiety.

NICE recommendations:

NICE does not recommend beta-blockers as first-line for generalised anxiety disorder (SSRIs are preferred) but acknowledges their use for short-term management of physical anxiety symptoms.