Beta-blocker: effects and side effects

Beta-blockers are standard medication for high blood pressure and heart failure. They lower heart rate and blood pressure. In the following article, doctors answer all questions about the effect, use, and side effects.

General effects

Beta-blockers are standard medication for high blood pressure and heart failure. They lower heart rate and blood pressure. In the following article, doctors answer all questions about the general and specific effects, use and side effects.

• general effects
• effect on high blood pressure
• effect on coronary heart disease and heart problems
• side effects

What are common beta-blockers and how do they work?

Beta-blockers are evident drugs, traditionally used to treat high blood pressure. Beta-blockers lower the heart rate and inhibit certain stress hormones by blocking specific receptors. Therefore blood pressure and workload on the heart are reduced.

Beta-blockers have three effects:

• Overactive nerve stimuli in the heart are down-regulated by blocking the receiving sites of adrenaline and noradrenaline (the so-called stress hormones). This means that the heart is protected. The pulse is lower and the heart works more efficiently.
• In the kidneys, they suppress the production of the hormone renin, which narrows the blood vessels.

Responsible for these two mechanisms is the interaction of beta-blockers with the sympathetic nervous system. The sympathetic nervous system controls the unconscious actions of the body, like the heart rate and blood vessel diameter.

The third effect is:

• Beta-blockers modulate the pressure sensitivity in veins and arteries, easing the blood flow. Accordingly, these three actions widen the vessels and decrease blood pressure.

Beta-blockers inhibit stress hormones

Arterial hypertension occurs when the pressure applied to the inner walls of the vessels is increased or when the heart and circulatory system transport too much volume overall, and the "tank" is too full. Beta-blockers start right here. They slow down the pulse, lower cardiac output, and thus the blood pressure.

There are tiny structures (receptores) on the surface of body cells, where normally the body´s own stress hormones, such as adrenaline and noradrenaline dock to. Both hormones stimulate circulation. They ensure, that the heart's pumping power increases and the heart beats faster in stressful situations. When high blood pressure occurs, this system is overactivated, too.

These so-called ß1- and ß2-adrenoreceptors are located in the heart cells, blood vessels and bronchi of the lungs. The receptors cannot be seen with the bare eye, they can only be described. Scientists use various state-of-the-art techniques, for example from biochemistry, biophysics or electron microscopy.

Beta-blockers fit into these structures, according to the same key-lock principle like the hormones. When there´s no vacant receptor to dock to, noradrenaline and adrenaline cannot affect the heart any longer. Thus, beta-blockers inhibit the effect of stress hormones and thereby lower blood pressure and heart rate.

What are beta-blockers prescribed for?

Beta-blockers are used for a whole range of diseases. Some are very effective for the treatment of high blood pressure. However, it is not always easy to find the most suitable beta-blocker and can take some time to adjust the adequate dose.

These include

• high blood pressure
• coronary heart disease (narrowed coronary vessels)
• prevention after a heart attack (prevention of a second heart attack)
• heart failure
• atrial fibrillation
• cardiac arrhythmias with a heartbeat that is too fast
• migraine prevention
• glaucoma

What are the different types of beta-blockers?

The common beta-blockers are distinguished as follows:

• Selective beta-blockers affect mainly the heart and kidneys.
• They are called non-selective beta-blockers when constricting the bronchi and small arteries, too. This can cause adverse side effects.
• The third group shows additional vasodilating effects. However, this does not result in a further decrease in blood pressure.

Selective beta-blockers are particularly prescribed to lower blood pressure.

The following active substances are among the beta-blockers:

• atenolol
• betaxolol
• bisoprolol
• carvedilol
• celiprolol
• metoprolol
• nebivolol
• propranolol
• talinolol

Beta-blocker against high blood pressure

Beta-blockers are among the standard drugs for high blood pressure. They have an overall calming effect on the cardiovascular system and they are often combined with other medications.

However, the antihypertensive efficacy of various beta-blockers varies. Beta-blockers of the so-called third-generation have an additional vasodilatory effect and lower blood pressure (carvedilol, nebivolol, etc).

These beta-blockers are particularly suitable for the treatment of high blood pressure. Low blood pressure, on the other hand, can lead to side effects such as headaches, fatigue, dizziness and loss of performance.

High blood pressure usually without reason

In Europe, three out of ten people (30%) have arterial hypertension (high blood pressure). It is one of the most common internal diseases and a risk factor for the quality of life and life expectancy. Because elevated blood pressure doesn't cause any pain, many people suffering from this disease don't know they are affected. Symptoms might occur when the pressure is higher than 200 mmHg, or you additionally suffer from a heart disease, for example.

High blood pressure develops over time with age and is favoured by factors such as obesity and lack of physical activity. Very seldom another disease can be blamed as a trigger. In 90% of all patients with high blood pressure, there is no direct cause. Doctors call this primary hypertension.

On the other hand, for a minority of 10%, other medical problems can be made responsible for hypertension. These include sleep apnea syndrome, a disorder of the endocrine system, or narrowing of renal vessels.

Beta-blockers with a particularly selective effect on the heart

There are some beta-blockers primarily recommended if you have high blood. They are also among the substances for treatment of heart rhythm disorder, especially if your heartbeat is too fast (tachycardia at rest, heartbeat above 90 beats per minute).
These beta-blockers include primarily:

• atenolol
• bisoprolol
• carvedilol
• metoprolol
• nebivolol
• propranolol

How long does it take for beta-blockers to show an antihypertensive effect?

The effect of beta-blockers on heart rate can occur within one to two days. For example, doctors initially use beta-blockers intravenously (into the vein) to quickly lower the pulse rate in cardiac arrhythmias. The medication takes effect immediately and the blood pressure drops directly.

In a long-term blood pressure, setting levels can change in the first days and it can take a few weeks for the beta-blockers, to develop the entire antihypertensive effect. It may take even longer until all drugs are found in their respective dosages and the blood pressure is finally well adjusted. So you have to be patient.

This applies to most blood pressure medications. Doctors usually wait two weeks before increasing the dose or adding another drug, depending on your readings.

The effect stops as slowly as it begins. When you discontinue beta-blockers, the antihypertensive effect can last for another one to two weeks. The reason: Even if most of the medication has been eliminated, there are still beta-blockers connected to receptors (anchoring points on the cells), which have to be released again.

What are the advantages of beta-blockers compared to other medicines for high blood pressure?

Beta-blockers are one of four major groups of medicines for arterial hypertension. Usually, they are not prescribed alone but combined with one or two other classes of antihypertensive drugs.

The four classes of antihypertensive substances mentioned are:

• beta-blockers
• diuretics (water pills )
• calcium antagonists (calcium channel blockers)
• regulators of the renin-angiotensin-aldosterone system (ACE inhibitors, Sartans)

Advantages for heart problems

Beta-blockers have certain advantages if coronary heart disease (CHD, narrowed heart vessels) or cardiac insufficiency is present parallel to high blood pressure since they calm and relieve the workload for the heart. In people with obesity or diabetes, on the other hand, they seem to have disadvantages compared to other substances.

Since several antihypertensives are usually prescribed together anyway (studies have shown that this improves blood pressure control), the question of the pros and cons is only of limited importance.

What are the disadvantages of beta-blockers in high blood pressure compared to other drugs?

Beta-blockers have disadvantages compared to other antihypertensive drugs, especially if certain diseases occur alongside hypertension. This applies, for example, to diabetes or obesity. Asthma can get worse, too, if you take the wrong beta-blocker.

And now a little more precisely:

Beta-blockers should not or only under certain circumstances be administered at a slow heartbeat. They can cause bradycardia (meaning a very slow heartbeat), irrespectively of whether you have a slow heartbeat by nature or due to heart disease.

Beware of: Asthma, COPD, diabetes

• Asthma and COPD are also reasons not to take beta-blockers (so-called contraindications) because most beta-blockers narrow the airways. If a beta-blocker is to be given yet, it must be more selective to avoid the bronchoconstrictive side effect as much as possible.
• Even people with a high risk of diabetes should be careful with beta-blockers because they can promote the development of diabetes.
• Even more important if you already have diabetes: In this case, the prescription of beta-blockers must be carefully considered. Taking beta-blockers can make you less aware of symptoms indicating hypoglycemia (e.g. due to insulin). Therefore, you should check your blood sugar more frequently, especially at the start of the therapy.
• If you have a severe allergy and are currently undergoing hyposensitization as an allergy therapy, beta-blockers can increase the allergic reaction.
• If you suffer from an arterial circulatory disorder, beta-blockers can worsen the blood flow.
• Beta-blockers can also worsen the symptoms of psoriasis.

Fatigue and listlessness

While the blood pressure setting takes a few weeks to adjust, side effects may occur. Doctors, therefore, start with rather low doses and gradually approach the required dose. Taking beta-blockers, some people initially feel weak, tired and listless.

These side effects usually disappear over time when the blood pressure is adjusted and the body has become accustomed to the change of interaction between noradrenaline, adrenaline and beta-blockers. Since different subtypes of beta-blockers are available, it is sometimes worthwhile to change drugs in the case of intolerances.

Abrupt stopping the medicine leads to tachycardia?

Doctors usually recommend stopping taking beta-blockers in several steps. The body has already become accustomed to the drug and has formed new docking sites due to the blocked receptors. If the beta-blocker is suddenly missing, many receptors are free. Consequently, noradrenaline and adrenaline can attack at once and thus lead to a rapid heartbeat.

Beta-blockers are therefore gradually reduced over a period of several weeks and eventually discontinued completely. This should always be done in consultation with your doctor.

Beta-blockers: Other indications for the heart

Beta-blockers have an overall beneficial effect on the heart. Therefore, they are not only useful to treat high blood pressure, but also to treat older people with other cardiac diseases. Accordingly, the primary areas of application are:

• coronary heart disease (narrowed coronary vessels)
• cardiac insufficiency
• angina pectoris
• after a heart attack

How do beta-blockers work in coronary heart disease?

Beta-blockers can influence the progression of arteriosclerotic alterations in the coronary arteries. By reducing the heart rate and volume, the heart has to work less.

Beta-blockers thus help to relieve the load on the heart and improve the oxygen supply to the heart muscle. Consequently, oxygen deficiency (ischemia) occurs less frequently. They also increase the ability to work under pressure and reduce symptoms such as angina pectoris (heart pain during exercise) at the same time.

The decrease of the heart rate also demonstrably leads to less secondary heart attacks after a heart attack. Beta-blockers increase the survival time after a heart attack and heart failure.

Beta-blockers also help to prevent a heart attack and are therefore important in preventive treatment if additional risk factors are present.

Are beta-blockers effective in angina pectoris?

Yes, beta-blockers are part of the basic treatment of stable angina pectoris. They reduce the frequency of seizures and improve blood circulation, therefore increasing the resilience. People who also have a fast heartbeat (tachycardia) and high blood pressure benefit in particular. Particularly people having both a fast heartbeat (tachycardia) and high blood pressure benefit most.

What are the benefits of beta-blockers after a heart attack?

Even if you have already suffered a heart attack and the heart is damaged, you can and should prevent a possible subsequent heart attack. Beta-blockers are a possible component of this secondary prevention for high-risk individuals.

Beta-blockers reduce the workload of the heart by decreasing the volume of blood that needs to be transported and by lowering the heart rate. Blood pressure drops. The heart muscle is less stressed and receives more oxygen.

So beta-blockers help to counteract a worsening of the disease and prevent another heart attack. Thus, they are effective drugs in aftercare and secondary prophylaxis.

Are beta-blockers effective in chronic heart failure?

Yes, beta-blockers can complement treatment with diuretics, ACE inhibitors and possibly digitalis. A cardiac insufficiency (heart failure) paradoxically activates the cardiovascular system, because the body tries compensating the pump weakness of the heart by mechanisms such as an increased heart rate.

However, this stimulation of the cardiovascular system has a negative effect on a heart failure itself. If the activation is prevented with beta-blockers, the heart is protected.

Are beta-blockers good for any type of heart failure?

No, not everyone with heart failure should receive beta-blockers.

In acute heart failure, for example, beta-blockers are not permitted. They reduce the power of the heart and therefore worsen the oxygen supply to the body. On the contrary, beta-blockers can improve cardiac insufficiency by lowering the heartbeat frequency if the issue is caused by accelerated heart rate and rhythm disturbances. This problem occurs, for example, in atrial fibrillation: the uneconomical and too fast heartbeat results in a lack of blood volume transported by the heart.

Are beta-blockers effective against cardiac arrhythmia?

Yes, all beta-blockers influence positively arrhythmic heart failures and have a stabilizing effect on both supraventricular (arrhythmia located in front of the ventricle) and ventricular (arrhythmia located in the ventricle) cardiac arrhythmias.

The beta-blocker metoprolol, for example, counteracts the occurrence of atrial fibrillation and also prevents prolonged ventricular tachycardia (rapid heartbeat).

Generally well tolerated

Beta-blockers are therefore used in medicine for people with high blood pressure, cardiac arrhythmia, heart stumbling, cardiac insufficiency or after a heart attack. But they can also help as migraine prophylaxis or against severe stage fright, for example with actors.

Beta-blockers protect your heart from a medical point of view. Nevertheless, they do not have a good reputation. Those affected often worry that problems such as fatigue, exhaustion or mood swings are caused by beta-blockers.

In fact, they can cause side effects such as low pulse, low blood pressure or severe asthma. In these cases, doctors must be careful. Diarrhoea, dizziness, increased walking pain in people with severely calcified leg vessels or problems with sugar control in diabetics can occur, too. The following chapter shall help you understanding the most common side effects and important facts, which are good to know when taking beta-blockers. But however, mostly beta-blockers are well tolerated and an indispensable substance for treatment of many diseases.

What side effects can beta-blockers have?

Frequent side effects of beta-blockers, especially at the beginning of therapy, are:

• headache
• insomnia
• fatigue
• dizziness

In the following a few more specific hints:

• Beta-blockers sometimes cause nightmares. Replacing the beta-blocker with another one might solve the problem.
• Circulatory disorders, especially in older individuals, often manifest themselves in the form of cold and tingling limbs.
• If you often feel tired, weak or unable to perform well, you should talk to your doctor about it. Particularly when fainting attacks occur.
• Depressive moods can be caused by beta-blockers, too.
• Some men complain about erectile dysfunction and women about vaginal dryness.
• Beta-blockers can make it difficult to lose weight.
• Beta-blockers are less protective against strokes and heart attacks compared to other drugs (e.g. ACE inhibitors).
• Beta-blockers can increase arterial stiffness.
• Beta-blockers can also slow down positive stress reactions such as heart palpitations and sweating during anxiety, arousal, joy or tension. This can be dangerous in road traffic, for example.

Now you might ask yourself: why beta-blockers at all? The answer is: Because they are often therapeutically very valuable, regardless of the mentioned disadvantages and possible side effects. And by the way, such a list of disadvantages could also be drawn up for most of active substances.

Do beta-blockers make you tired?

Yes, quite often. Especially in the first days and weeks of treatment. Feeling more tired and weaker than usual can be a typical side effect.

This is because beta-blockers reduce the effects of stress hormones such as adrenaline and noradrenaline. This calms and relieves the heart and additionally lowers the blood pressure. But it also makes you a little bit tired, especially at the start of the therapy.

Not only the heart calms down

These transmitters are part of a system called the sympathetic nervous system by physicians. It is responsible for activating the body, for its agility, alertness and conductivity. When we humans wanted to kill a mammoth in the forest or had to flee from a predator in ancient times, the sympathetic nervous system was activated unconsciously. Today, of course, this still happens. For example during sports, in stressful situations or when a horde of thugs meets you on the street.

But back to the topic: Beta-blockers reduce the effect of the sympathetic nervous system. And, thus, also the mediated effects. Depending on the respective active ingredient, its dosage and your individual reaction to both, a certain listlessness can appear under medication. Usually, this settles down and the side effects disappear again.

Which beta-blockers can cause erectile dysfunction in men?

If you have been prescribed a beta-blocker (bisoprolol, metoprolol or others) and have had impotence or libido weakness since it is possible these problems are related to the medication. Especially if you suffer from this condition, do not be afraid to discuss it with your doctor or health care professional. It might be worth trying another drug or a third-generation beta-blocker, such as Nebivolol (Nomexor).

Erectile dysfunctions can, of course, have many reasons and are often difficult to treat. In this special drug-related case, however, it would be very easy to eliminate the cause - but please only in cooperation with your doctor, not in an unauthorized weaning attempt. Don´t forget, the protection of the heart is most important overall.

The following active substances are among the beta-blockers, causing potency problems as side effects (active substances):

• atenolol
• bisoprolol
• carvedilol
• metoprolol
• nebivolol
• pindolol
• propranolol

Beta-blockers: what other medications do you have to be careful with?

Beta-blockers may interact with the following medications:

• Drugs against depression, the MAO inhibitors; this interaction can lead to an insufficient decrease in blood pressure and high blood pressure.
• Certain painkillers, non-steroidal anti-inflammatory drugs (NSAIDs) such as Ibuprofen, ASAID or Diclofenac; this combination can lead to an increased lowering of blood pressure.
• Medications that lower the heart rate; in combination with beta-blockers, they can reduce the heart rate too much. Also be careful if you have diabetes or are taking blood sugar-lowering medications (insulin, metformin, etc.). Problems occur if these drugs act too strongly and cause hypoglycemia. This is not interaction in the strict sense, but the beta-blockers can mask signs of hypoglycemia and you will notice symptoms like tachycardia or sweating later than usual.
• It is common for several antihypertensives to be prescribed together to treat high blood pressure. For example, a beta-blocker, an ACE inhibitor and a diuretic. Nevertheless, it should be noted that the effect on blood pressure is naturally increased. This is the therapeutic purpose, but also increases the risk of low blood pressure, which can manifest itself in dizziness or fainting.

What happens when I stop taking beta-blockers suddenly?

Discontinuing beta-blockers too suddenly can cause symptoms such as restlessness, anxiety, insomnia and sweating.

Stopping the treatment with beta-blockers due to complaints or side effects must be done carefully and slowly. The dosage has to be reduced gradually because the body has already become used to it.

This is because the body produces more receptors during therapy with beta-blockers as a counter-regulation. If the drug is suddenly discontinued, there are far more anchorages for the hormones adrenaline and noradrenaline than before. They can activate all these receptors simultaneously and thus over-stimulate the circulation. Blood pressure and pulse can rise or cardiac arrhythmias can occur.

This mechanism is called a rebound or weaning phenomenon. Restlessness, anxiety, insomnia and sweating can torture you if you suddenly stop taking beta-blockers. Therefore, always discuss with your doctor whether to stop therapy and how long the gradually reduced dosage has to be taken.