Does Metoprolol Cause Erectile Dysfunction?

What is metoprolol?

Metoprolol,¹ also known as Lopressor, is an FDA-approved beta blocker for treating angina, heart disease, hypertension, myocardial infarction, and atrial fibrillation/flutter. In some cases, it can also help to prevent migraines. 

For oral administration, there are immediate-release and extended-release options available. The immediate-release formulation is usually taken twice a day, and the extended-release formulation typically only needs to be taken once a day. 

Metoprolol is on the World Health Organization’s (WHO) list of essential medicines and is a very commonly prescribed drug. In 2019, it was the 5th most frequently prescribed drug in the United States. 

How does metoprolol work?

Normally, the activity of your heart is influenced by a range of signals from inside your body, such as hormones from your endocrine system and neurotransmitters from your nervous system. It can also be affected by many different types of drugs. 

Such drugs often mimic or counteract the effects of your natural signaling molecules. 

Metoprolol works by blocking the effects of adrenaline/noradrenaline on your heart. 

While adrenaline/noradrenaline normally increases both your heart rate and forcefulness of contractions, metoprolol lowers your heart rate and blood pressure, helping to reduce the stress on your cardiovascular system.

Side effects of metoprolol

As with most drugs, metoprolol can produce various adverse side effects. Some of these are related to the drug’s effects on your heart, while others are due to its effects on different organs and tissues in your body. 

One of the reasons that metoprolol can cause a wide range of side effects is that the type of receptor it binds to (the beta-1 adrenoceptor) is present in many different types of cells and tissues, not just heart muscle, and has multiple roles in normal body functioning. 

The primary adverse effects of metoprolol include:

• Heart failure

• Hypotension

• Fatigue

• Depression

• Cold extremities

• Dizziness

• Decreased libido

• Diarrhea

• Tinnitus

• Decreased exercise tolerance

• Glucose intolerance

Does metoprolol cause erectile dysfunction?

Men treated with beta-blockers for high blood pressure often complain of ED. However, ED is usually a symptom of underlying cardiovascular diseases that also cause things like high blood pressure. This means that the correlation between beta-blocker use and ED is at least partly due to the common cause of cardiovascular disease. 

However, beta-blockers such as metoprolol decrease your heart's maximum pumping capacity, which could reduce some blood flow to your penis that you need for an erection. So it is possible that metoprolol could worsen ED caused by cardiovascular disease. 

Several studies have compared metoprolol with other beta-blockers to compare their effectiveness for treating cardiovascular disease and their potential for causing different side effects, such as ED. 

One study² from 2017 compared the effects of metoprolol with nebivolol on ED among 119 male patients recovering from coronary artery bypass surgery.

Following their surgeries, the patients were randomly divided into two groups. The first group of 57 patients was given 50mg per day of metoprolol succinate, while the second group of 62 patients was given 5mg per day of nebivolol for at least three months. 

Both groups were sexually active during this time and were asked to complete a short questionnaire regarding the quality of their own erections called the International Index of Erectile Functioning 5 (IIEF-5). The results of the questionnaire gave each patient a numerical score from 5-25, with lower scores representing more severe ED and scores of 21 or higher considered normal. 

The study found that men receiving metoprolol tended to get lower scores than men receiving nebivolol. The average score in the group receiving metoprolol was 13.79 ± 6.00. While the average score in the group receiving nebivolol was 16.02 ± 5.50.

The authors determined that this score difference was statistically significant (p = 0.036), meaning it was unlikely to be due simply to chance. The effect size was quite small, however. 

Metoprolol is only one of several different kinds of beta-blockers available. So if you are experiencing worsened ED after being prescribed metoprolol, you should talk to your doctor about possible alternative treatments. 

How do beta-blockers affect erectile dysfunction?

For an erection to develop, additional blood needs to flow into the penis — this depends on two main factors. One is the ability of the heart to pump enough blood to the penis, and the other is the ability of the blood vessels in the penis to relax to allow the additional blood inside. 

Most kinds of beta-blockers reduce the maximum pumping capacity of the heart, which can reduce blood flow to extremities, potentially including the penis. Reduced exercise capacity is another side effect of most beta-blockers, which can also impair sexual performance. 

In addition to direct effects on the heart, some beta-blockers also directly affect the penis. They can interfere with the relaxation of the blood vessels inside the penis, which is necessary to achieve normal erections. Examples include older-generation non-selective beta-blockers such as propranolol.³ 

Some newer-generation beta-blockers, such as metoprolol, are more selective for adrenoceptors in the heart (cardioselective) and have fewer effects on adrenoceptors in the penis. However, they could still potentially worsen ED and overall sexual performance by reducing cardiac output. 

Blood pressure medications that do not often cause ED

ED is often a side effect of drugs, and blood pressure medications, in particular, have frequently been associated with ED in men. The blood pressure drugs most often associated with ED are thiazide diuretics, loop diuretics, and beta-blockers. 

Blood pressure medications much less likely to be associated with ED include alpha-blockers, ACE inhibitors, and angiotensin receptor blockers. 

Not all beta-blockers are the same, however, as there are several different subtypes of beta-adrenergic receptors in the body (e.g., B1, B2, and B3), and the effects of a particular beta blocker will depend on its relative affinity for the different types of receptors. 

Beta-blockers that are more selective for the B1 receptor are considered less likely to cause or worsen ED than less selective beta-blockers. This is because B1 receptors are mostly expressed in the heart, kidney, and fat cells rather than in the penis. 

Examples of beta-blockers that primarily target the beta-1 subtype of adrenoreceptor include metoprolol, acebutolol, and esmolol. 

Interestingly, some beta-blockers may actually help treat ED. For example, a 2017 literature review⁴ identified four studies that had compared nebivolol with other beta-blockers.

Two of the four studies found that patients on nebivolol experienced significantly improved erectile function compared to other beta-blockers. The other two studies found that nebivolol was not significantly worse for ED than other beta-blockers. 

One possible mechanism by which nebivolol might help with ED is that it can promote the release of nitric oxide from endothelial cells inside the arteries of the penis. This can cause them to dilate and allow more blood to flow in. 

ED treatment

Oral medications

There are currently several oral medications available for the treatment of ED. Some of the most commonly prescribed ones are sildenafil (Viagra), avanafil (Stendra), tadalafil (Cialis), and vardenafil (Levitra). 

These all work by inhibiting an enzyme called phosphodiesterase 5 (PDE-5). They do not directly cause erections, but they make it easier to gain and maintain erections long enough to satisfy sex in most cases. 

The side effects of PDE-5 inhibitors are usually mild and short-lived. They should not be used more than once per day, however, and should not be used by patients taking nitrates or guanylate cyclase stimulators such as riociguat, as this can lead to dangerous drops in blood pressure. 

Applied medications 

Another option for patients with ED who cannot take oral PDE-5 inhibitors is to try alprostadil. Alprostadil works differently than PDE-5 inhibitors and is classed as a prostaglandin E1 (PGE-1) agonist. It also needs to be applied directly to the penis.

There are several ways in which this can be done. 

One is a urethral suppository, a pill you insert inside your penis via the opening at the tip. Another is by direct injection into the base of the penis. 

Unlike the oral PDE-5 inhibitors, alprostadil does directly cause erections. Normally, if you plan to use alprostadil suppositories or injections, your doctor will help you do it the first time in their office. 

In some countries, such as the UK and Canada, alprostadil is also available in a cream formulation (Vitaros). Vitaros is not currently available in the US, however. 

Most ED drugs aim to produce erections that last up to around 1 hour and should not be used more than once daily. While you might be tempted to take more than the recommended dose to try and get even longer-lasting erections, this is not recommended and can be dangerous. 

Longer-lasting erections start to become painful and can lead to a condition called priapism, which is an erection that lasts longer than 4 hours. This is a medical emergency as it can lead to permanent damage to your penis. If you experience priapism, you should immediately stop taking your ED drug and see a doctor. 

The lowdown

beta-blockers are drugs commonly prescribed for patients with heart-related problems such as high blood pressure and angina. They work by blocking some of the normal stimulatory effects of epinephrine/norepinephrine on the heart and can thereby reduce the overall stress on a patient’s cardiovascular system.

The use of beta-blockers is sometimes associated with erectile dysfunction, which is a common concern for older male patients and their partners. 

The best thing you can do if you are experiencing ED is to consult with your doctor or pharmacist. In many cases, ED is a side effect of medication, so you may be able to find alternative medications that do not cause ED. There are also many treatments available that might be able to help you.