Beta-blockers are primarily used to treat cardiovascular conditions such as high blood pressure and heart failure. There are several different beta-blocker drugs on the market, the characteristics of which can be diverse. Here are the answers to 5 of the most frequently asked questions about these commonly used drugs.

What are beta‑blockers?

Beta-blockers are a class of drugs used to treat a range of conditions, including high blood pressure (hypertension), chest pain (angina), and heart failure, often in combination with another drug. They help lower your heart rate by preventing certain hormones from binding to beta receptors.

There are different types of beta-blockers available, which are usually grouped into three subcategories (which you can read about in question 3: Are all beta-blockers the same?)

Beta-blockers are most commonly available as tablets. They can also come in other forms, including capsules, eye drops, liquid solutions, and injectables.

What are beta-blockers used for?

Beta-blockers have a range of uses. They are most commonly used to treat hypertension, heart failure, chest pain (angina), heart rhythm disorders, and as protection against recurrent heart attacks. They are often used in combination with other medications, such as ACE inhibitors and calcium channel blockers. Some beta-blockers, such as propranolol, are approved to treat migraines.

Beta-blockers may also be used to treat symptoms related to hyperthyroidism, such as a rapid heart rate (tachycardia). However, they do not alter thyroid hormone levels, so are not used to treat the underlying cause of the symptoms.

Beta-blockers are available in eye drop form to treat glaucoma, although they are not usually the first treatment option due to the possibility of cardiovascular side effects.

Beta-blockers may additionally be used ‘off-label’ (in a manner not approved by the FDA or your country’s equivalent regulatory body) to treat symptoms of anxiety, such as a rapid heart rate and tightness in the chest. As is the case when they are used to treat hyperthyroidism, beta-blockers do not treat the underlying cause of anxiety and are not used in this way as regularly as they once were.

How do beta-blockers work?

Beta-blockers primarily work by ‘blocking’ adrenergic beta receptors, which prevents adrenaline and noradrenaline from binding to them. Adrenaline and noradrenaline are hormones that increase your heart rate, so blocking them from binding to receptors slows your heart rate down and helps lower your blood pressure.

However, there are key differences between different types of beta-blockers.

Are all beta-blockers the same?

There are three known types of adrenergic beta receptors, called beta₁ (β₁, found mainly in your heart and kidneys), beta₂ (β₂, found mainly in your liver, lungs, skeletal muscles, vascular smooth muscle, gastrointestinal tract, parts of your eye, and various other locations in your body) and beta₃ (β₃, found mainly in fat cells). One of the differences between different beta-blockers is the receptors they block.

Beta-blockers are usually grouped into three subcategories:

First-Generation Beta‑Blockers

First-generation beta-blockers are ‘non-selective’ β₁ and β₂ blockers, which means they affect your heart, kidneys, liver, lungs, skeletal muscles, vascular smooth muscle, and gastrointestinal tract, among other parts of your body. First-generation beta-blockers include:

• Propranolol
• Timolol
• Sotalol

Second-Generation Beta‑Blockers

Second-generation blockers are ‘selective’ and act primarily upon β₁ receptors. This means they predominantly affect your heart and, to a lesser extent, your kidneys. Because they do not affect other parts of your body, second-generation beta-blockers may be safer for certain people, such as those living with lung disease. Second-generation beta-blockers include:

• Metoprolol
• Atenolol
• Bisoprolol

Third-Generation Beta‑Blockers

Carvedilol and nebivolol are third-generation beta-blockers. Like first-generation beta-blockers, they are ‘non-selective’ β₁ and β₂ blockers. However, they have additional characteristics that set them apart from first-generation beta-blockers. For example, they have also been found to have vasodilating effects, which means they widen blood vessels. This can provide extra therapeutic benefits. Additionally, they tend to cause fewer metabolic side effects and do not decrease nocturnal melatonin release, which is believed to be a cause of sleep disturbance associated with first- and second-generation beta-blockers. Third-generation beta-blockers include:

• Carvedilol
• Nebivolol

Other Differences

There are several other differences between beta-blockers. Some have a curious ability to both block beta receptors and partially stimulate (agonize) them, a phenomenon known as ‘intrinsic sympathomimetic activity’ (ISA), which gives them unique characteristics compared to regular beta-blockers. Other differences between beta-blockers include their solubility in water and the part of the body in which they are metabolized and excreted.

These variabilities give each type of beta-blocker a unique set of characteristics. There is, therefore, no ‘best’ beta-blocker for everyone; rather, it depends on the exact nature of the treatment required.

Your doctor will take your personal situation into account when deciding whether to prescribe a beta-blocker and, if so, which one. If you have any concerns or questions regarding your treatment, you should speak to your doctor or pharmacist.

What are the side effects of beta‑blockers?

Beta-blockers are usually well tolerated. Like any drug, however, they can cause side effects. The side effects associated with beta-blockers vary from drug to drug, due to the differences discussed in the previous question. Nonetheless, some of the more common side effects include:

• Cold hands or feet
• Fatigue
• Dizziness
• Nausea
• Sleep disturbance

Some of the less common side effects include:

• Depression
• Shortness of breath
• Weight gain
• Swelling in your hands or feet

Side effects are often mild and will go away as your body gets used to the medication. However, if side effects are more severe, persistent, or get worse, you should speak to your doctor as soon as possible.

This is not a comprehensive list of the possible side effects of beta-blockers. You should speak to your doctor and read the information label to learn more about the side effects of the specific beta-blocker you are taking.

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