Propranolol side effects: what you need to know

Propranolol is a non-selective beta-blocker. Doctors prescribe it for anxiety, migraine prevention, essential tremor (uncontrollable shaking) and heart conditions.

Its side effects come from the way it blocks beta-1 and beta-2 adrenergic receptors. These are signal sites for adrenaline, and they sit all over the body.

Very common and common side effects:

• Fatigue and tiredness: this is one of the most reported effects. It happens because the heart pumps less and blood pressure falls. Many people say they simply feel less energetic
• Cold extremities: cold hands and feet are typical of beta-blockers. They happen when blocked beta-2 receptors in the blood vessels make those vessels narrow. This affects about 10 to 15% of patients
• Dizziness and lightheadedness: this links to lower blood pressure. It is worse when you stand up quickly (postural hypotension)
• Bradycardia: a slow heart rate, below 60 beats per minute, is expected with beta-blockers. Usually you feel nothing, but it can sometimes cause dizziness or faintness
• Sleep disturbance: propranolol passes easily into the brain. In some people this causes vivid dreams, nightmares or trouble sleeping
• Nausea and stomach upset: usually mild and short-lived
• Dry eyes: this matters if you wear contact lenses

The BNF lists these as known effects of non-selective beta-blockers. They generally depend on the dose. They tend to be most noticeable in the first few weeks of treatment.

Serious side effects are uncommon, but they need prompt medical attention.

Bronchospasm:

Propranolol blocks beta-2 receptors in the lungs. This can narrow the airways. For this reason propranolol must not be used in asthma.

Even people without a formal asthma diagnosis should avoid non-selective beta-blockers if they have a history of wheezing. Watch for shortness of breath, wheezing and chest tightness.

Get emergency help if these happen.

Severe bradycardia and heart block:

If the heart slows too much, it can cause:

• Fainting or near-fainting
• Severe dizziness
• Deep, heavy tiredness

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

Hiding low blood sugar:

Propranolol can mask the warning signs of low blood sugar, such as tremor, palpitations and sweating. This matters most for people with diabetes who take insulin or sulphonylureas.

The BNF advises caution with beta-blockers in diabetes.

Severe hypotension:

A large drop in blood pressure may cause fainting. The risk is higher in people who already take other blood pressure medicines.

Worsening peripheral vascular disease:

Propranolol narrows blood vessels in the limbs. This can worsen Raynaud's phenomenon (fingers and toes that go cold and pale) or intermittent claudication (leg pain when walking).

Do not stop propranolol suddenly. This can cause a rebound fast heart rate and high blood pressure.

In people with ischaemic heart disease (reduced blood supply to the heart), it can trigger angina or even a heart attack.

Propranolol passes into the brain more easily than many other beta-blockers. Because of this, it can affect the central nervous system.

Sleep disturbance:

• About 5 to 10% of patients report vivid dreams and nightmares
• Some people sleep badly or wake often
• These effects are more common with propranolol than with water-loving beta-blockers such as atenolol
• Taking the last dose in the late afternoon, rather than at bedtime, may help

Mood changes:

• Low mood or depression: people have long debated whether beta-blockers cause depression. Current evidence suggests the risk is small but real. It is more likely with fat-loving drugs like propranolol
• Lethargy and low motivation: some people feel their emotions are flatter than usual
• For people who take propranolol for anxiety, the overall effect on mood is usually positive

Cognitive effects:

• Some people find it harder to concentrate or notice mild memory problems
• These effects are usually slight and depend on the dose

Sexual dysfunction:

• Erectile dysfunction has been reported with beta-blockers, including propranolol
• This may be due to reduced blood flow and changes in the sympathetic nervous system (the body's stress response)
• This is worth raising openly with your prescriber

If these effects bother you, your prescriber may suggest a switch. Options include a cardioselective beta-blocker, such as bisoprolol, or a water-soluble one, such as atenolol.

These pass into the brain less easily.

You can ease many propranolol side effects with simple steps and dose changes.

Cold hands and feet:

• Wear warm gloves and thick socks, especially in cold weather
• Regular exercise can help blood flow to the hands and feet
• Avoid smoking, which makes blood vessels narrow more
• If it is severe, your prescriber may switch you to a cardioselective beta-blocker

Fatigue:

• Take propranolol when tiredness will get in the way least, for example an evening dose
• Stay active, as regular exercise can fight the tiredness
• Get enough sleep and drink enough fluids
• If fatigue is severe, a lower dose may help

Dizziness:

• Stand up slowly from sitting or lying down
• Avoid standing for a long time in hot places
• Drink plenty of fluids
• Tell your prescriber about frequent dizziness, as your dose may need a change

Sleep problems:

• Take the last dose at least 4 to 6 hours before bedtime
• Keep good sleep habits: a regular schedule, a dark room, and no screens before bed
• If nightmares carry on, talk about changing the timing or trying a different medicine

General advice:

• Never stop propranolol suddenly. Always cut the dose down slowly over 1 to 2 weeks, with medical supervision
• Go to your regular reviews, especially in the first few months
• Keep a symptom diary to talk through at appointments

Some conditions make propranolol unsafe or call for extra care.

Absolute contraindications (do not take):

• Asthma or a history of bronchospasm: non-selective beta-blockers can trigger airway narrowing that is life-threatening
• Uncontrolled heart failure: propranolol makes the heart pump less, which can worsen sudden heart failure
• Severe bradycardia: a resting heart rate below 50 bpm is usually a reason not to take it
• Second or third-degree heart block: unless a pacemaker is fitted
• Prinzmetal's angina: chest pain caused by spasm in a coronary artery
• Phaeochromocytoma (an adrenal gland tumour), unless an alpha-blocker is given first

Relative contraindications (use with caution):

• Diabetes: propranolol hides the signs of low blood sugar and can slow recovery from it
• Peripheral vascular disease: it may worsen claudication or Raynaud's phenomenon
• COPD without reversible airways disease: cardioselective beta-blockers are preferred
• First-degree heart block: monitor the ECG (heart tracing)
• Liver impairment: the liver breaks down most of the drug, so the dose may need to be lower
• Myasthenia gravis: beta-blockers may worsen this muscle weakness condition

Pregnancy and breastfeeding:

• Propranolol can be used in pregnancy when the benefit outweighs the risk. The baby should be checked for slow heart rate and low blood sugar after birth
• Small amounts pass into breast milk, so seek specialist advice

The BNF gives full lists of contraindications and cautions for all beta-blockers.

Propranolol is one of many beta-blockers used in the UK. Two things set it apart: it is non-selective, and it is fat-loving (lipophilic), so it passes easily into the brain.

Propranolol versus bisoprolol:

• Bisoprolol is cardioselective (it acts mainly on beta-1 receptors). So it affects the lungs and limb blood vessels less
• Bisoprolol is preferred for people 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 the beta-2 receptors that drive those symptoms

Propranolol versus atenolol:

• Atenolol is cardioselective and water-soluble, so it passes into the brain less easily
• Atenolol causes fewer sleep problems and nightmares than propranolol
• Propranolol usually works better for performance anxiety and physical anxiety symptoms

Why propranolol is chosen for anxiety:

The physical signs of anxiety are tremor, palpitations, sweating and a shaky voice. These come from beta-2 receptors in the body and from adrenaline in the blood.

Propranolol blocks beta receptors widely, so it is good at calming these signs.

That is why it is the most prescribed beta-blocker for anxiety and one-off performance anxiety.

NICE recommendations:

NICE does not recommend beta-blockers as first-line for generalised anxiety disorder, as SSRIs are preferred. But NICE does accept their use for short-term control of physical anxiety symptoms.