What Do Beta-Blockers Do, and Why Do They Make Some People Tired?

Beta-blockers can make some people feel tired, most often in the first weeks, because they slow the heart rate and lower blood pressure. They block the effects of adrenaline on the heart and blood vessels, and the reasons for tiredness are not fully understood. This article explains how they work, why fatigue can happen, what may help, and which symptoms need urgent care.

What beta-blockers do in the body

Adrenaline and noradrenaline are the body's "go" signals. They attach to beta receptors on heart muscle and blood vessels, which makes the heart beat faster and harder. Beta-blockers sit on those receptors and reduce how strongly the signals land. The result is usually a slower, steadier heartbeat and lower pressure inside the arteries.

Because of this effect, clinicians may prescribe beta-blockers for several heart-related conditions. MedlinePlus gives a plain-language overview of heart failure, a condition in which the heart cannot pump as well as the body needs. A review of beta-blocker treatment optimization in chronic heart failure describes three beta-blockers (carvedilol, metoprolol succinate and bisoprolol) as the ones used for heart failure with reduced ejection fraction, meaning the heart pumps with reduced force, and your prescriber decides whether that applies to you. Beta-blockers are also used for high blood pressure, certain heart rhythm problems, angina (chest pain from reduced blood flow to the heart), and after some heart attacks. Outside the heart, some people take them for migraine prevention or tremor, and some eye drops contain a beta-blocker for glaucoma.

Common names and how they differ

Many beta-blockers end in "-olol," such as metoprolol, atenolol, propranolol, bisoprolol and nadolol. Carvedilol and labetalol also block alpha receptors, which relaxes blood vessels further. Some are described as "cardioselective," meaning they act mainly on the heart rather than the lungs and other tissues. Selectivity is relative and not absolute, so differences between medicines are a matter for your prescriber and pharmacist to explain.

Ask which one you take and why it was chosen for you. The same drug class can feel quite different from person to person.

Why beta-blockers can make you tired

Tiredness is a commonly reported side effect listed in beta-blocker prescribing information, and the reasons are not fully understood. Several factors may contribute. Here are the explanations clinicians often discuss:

• A slower heart rate. With fewer and gentler beats, the heart may not raise its output as readily during stairs, walking uphill or exercise. Effort can feel harder than before.
• Lower blood pressure. Pressure that is lower than your body is used to can leave you feeling sluggish or lightheaded, especially after standing up.
• Effects on the brain. Some beta-blockers, such as propranolol, are more fat-soluble and cross into the brain more easily than others. This may contribute to poor sleep, vivid dreams or low energy in some people.
• The underlying condition. Heart disease, high blood pressure, poor sleep and low mood can all cause fatigue by themselves. It can be hard to tell the medicine from the illness.

Fatigue is often most noticeable in the first weeks after starting or after a dose change, and it eases in some people as the body adjusts. That is not true for everyone, and outcomes vary. Do not stop the medicine because of it; talk to your prescriber, especially if the tiredness comes with a slow pulse or dizziness.

Other side effects to know about

• Cold hands and feet.
• Dizziness, particularly when standing quickly.
• Slow pulse, which may feel like fatigue or lightheadedness.
• Sleep changes, including vivid dreams.
• Reduced exercise tolerance.
• Sexual side effects, reported by some people.
• Mood changes or low mood in some people. Tell your clinician about this.

Beta-blockers can narrow the airways in some people, especially with asthma or other lung disease. Report new wheezing or worse breathing to your prescriber the same day, and do not self-manage it by changing your medicines. Call 911 for severe trouble breathing or wheezing that does not ease.

Beta-blockers can also blunt some warning signs of low blood sugar, such as a racing heartbeat or shaking, in people who take insulin or certain diabetes medicines. Sweating may be less affected. If you take insulin or other diabetes medicines, keep following your clinician's blood sugar monitoring plan, and tell your clinician about repeated low readings. Low blood sugar with confusion, seizure, or being unable to swallow or wake up is an emergency. If you have diabetes or asthma, tell every clinician who prescribes for you.

Do not stop a beta-blocker on your own

Stopping a beta-blocker suddenly can cause a fast heartbeat, higher blood pressure, worse angina or dangerous heart rhythms, especially in people with coronary artery disease, where abrupt withdrawal has been linked to serious heart events such as heart attack. The prescribing information (product label) for beta-blockers such as metoprolol and atenolol carries a boxed warning about stopping suddenly in people with coronary artery disease; check the label for your own product, and your pharmacist can show it to you. Do not skip doses, change the timing or lower the dose without speaking to your prescriber. Any taper is a plan your prescriber sets and supervises. If you have already stopped and have chest pain, call 911; otherwise call your prescriber or pharmacist the same day.

If you run out of your medicine or have missed several doses, contact your prescriber or pharmacist the same day, including if you notice a racing or irregular heartbeat. Call 911 if chest pain or pressure develops after stopping, or if a racing or irregular heartbeat comes with fainting, chest pain or trouble breathing. If tiredness is wearing you down, tell your prescriber. They may adjust the plan safely, change the medicine, or look for another cause.

Taking much more than prescribed can be dangerous, and symptoms may be delayed, especially with extended-release products. For any suspected large overdose, call Poison Control at 1-800-222-1222 or 911 right away, even if the person feels fine.

If you miss a dose, our related article on what to do if you miss a dose of your blood pressure pill covers the general approach, and your pharmacist can advise on your specific product.

How to manage tiredness on a beta-blocker

Some practical steps may help, and none replaces advice from your clinician:

• Keep a short log of when you feel tired, your pulse and your blood pressure if your clinician has asked you to track them. Do not stop any monitoring your care team recommended.
• Stand up slowly from sitting or lying down.
• Keep moving in a way your clinician considers safe for you. Gentle regular activity may support energy over time, and MedlinePlus lists general habits that support heart health.
• Bring up sleep problems, low mood, or snoring. These can also cause daytime fatigue.
• Ask whether other medicines, such as other blood pressure or heart-rate medicines (for example verapamil or diltiazem) or sleep aids, could be adding to the effect. Some combinations can slow the heart a great deal, so your prescriber and pharmacist should know everything you take.

Questions to bring to your appointment

• Why am I taking this beta-blocker, and what is it meant to do for me?
• Could the dose or the type be adjusted if I feel too tired?
• Is my resting heart rate in a range you are comfortable with?
• Do I need any heart health tests to check how my heart is doing?
• Do my other conditions, such as asthma or diabetes, change how I should use this medicine?

Fatigue has many everyday causes. For related patterns, see our pages on feeling tired after meals and on heavy, tired legs. This article stays with what is specific to beta-blockers.

When tiredness is more than a side effect

Fatigue may also be a sign that heart failure is getting worse, that the heart rate is too slow, or that something unrelated is going on. Swelling in the legs, quick weight gain, new shortness of breath when lying flat, or a pulse that feels much slower than usual call for same-day contact with your clinician. Call 911 if breathing is severe or comes with chest pain or fainting. Lightheadedness, weakness or a pulse much slower than usual for you needs same-day contact with your clinician; call 911 if it comes with fainting, confusion, chest pain or trouble breathing. The lists below separate emergency symptoms from those that call for same-day or next-available care.

When to Seek Medical Care