Tenormin (Atenolol) – Oral

What Is Tenormin?

Tenormin (atenolol) is an orally administered prescription medication used alone or in combination with other medications to treat hypertension (high blood pressure), prevent angina (chest pain), and improve the odds of survival following a heart attack in adults 18 and older.

Tenormin is in a drug class called beta-blockers. Beta-blockers, also referred to as beta-adrenergic blocking agents, are drugs used to treat cardiovascular diseases and other conditions involving the circulatory system.

Beta-blockers inhibit the effects of stress hormones, such as adrenaline on the heart.

Tenormin works by relaxing blood vessels and slowing down an individual's heart rate. This helps to improve blood flow and lower blood pressure. 

The active ingredient present in Tenormin, atenolol, is also available as a generic product administered in the form of oral tablets.

However, this article will focus on the brand-name drug, Tenormin, an oral medication that is administered via oral tablets. 

Drug Facts

Generic Name: Atenolol

Brand Name(s): Tenormin

Drug Availability: Prescription

Administration Route: Oral

Therapeutic Classification: Cardiovascular agent

Available Generically: Yes

Controlled Substance: N/A

Active Ingredient: Atenolol

Dosage Form(s): Tablet

What Is Tenormin Used For?

The Food and Drug Administration (FDA) has approved Tenormin to be used for the following in people age 18 and older:

  • Alone or in combination with other drugs to treat hypertension
  • To prevent chest pain 
  • To improve survival after a heart attack

Hypertension is a relatively common condition in American adults, and if not treated, it can cause severe damage to the heart, kidneys, blood vessels, and brain.

Damaged organs may lead to heart disease, stroke, kidney failure, loss of vision, and other conditions.

How to Take Tenormin

Before taking Tenormin, read the information leaflet that comes with your prescription. Ask your healthcare provider any questions you have. 

Tenormin comes as a tablet to take by mouth. It is usually taken once or twice a day.

Take Tenormin (and any other medications prescribed for your condition) exactly as prescribed by your healthcare provider. It may take several weeks before the medication reaches its full effect. Do not stop taking Tenormin unless your healthcare provider tells you to do so.

Hypertension often does not have symptoms. Keep taking Tenormin even if you do not have symptoms. 

Your healthcare provider will give you instructions on checking your blood pressure at home. If you are having any type of surgery, notify your surgeon ahead of time that you take Tenormin.


Tenormin should be stored at room temperature (68 to 77 degrees F), away from heat, and direct light. Also, do not store it in a bathroom or in any area susceptible to high levels of moisture.

Keep Tenormin in its original labeled container and out of the reach of children and pets. Keep the bottle tightly closed when not in use.

Off-Label Uses

Sometimes Tenormin is used off-label for indications that are not FDA-approved.

Sometimes healthcare providers prescribe Tenormin to people to:

How Long Does Tenormin Take to Work?

One dose of Tenormin reaches its highest level in two to four hours. However, it can take up to two weeks to see the full effect of this medicine.

What Are the Side Effects of Tenormin?

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at www.fda.gov/medwatch or 800-FDA-1088.

Common Side Effects

The most common side effects of Tenormin are:

Severe Side Effects

Call your healthcare provider right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency.

Serious side effects and their symptoms can include the following:

  • Anaphylaxis (hypersensitivity reactions, with life-threatening symptoms that include difficulty breathing, rash, hives, and swelling around the lips, tongue, and face requiring emergency medical care)
  • Heart conditions, such as congestive heart failure, severely slow heart rate, heart block, or ventricular arrhythmia (an abnormal heartbeat that originates in the lower heart chambers called ventricles)
  • Raynaud’s phenomenon (feeling numbness and coldness in the fingers, toes, ears, and tip of the nose)
  • Bronchospasms
  • Lupus erythematosus (an autoimmune disease in which the body's immune system attacks its own tissues and organs; with symptoms including fatigue, rash, joint pain, and fever)  

Also, stopping Tenormin abruptly can cause the following:

  • Ventricular arrhythmia
  • Worsening chest pain
  • Heart attack

Call your healthcare provider right away if you have new or worsening chest pain, slow or uneven heartbeat, shortness of breath, swelling, or rapid weight gain.

If you feel like you might pass out, or if you feel cold in your hands and feet, call your healthcare provider right away.

Long-Term Side Effects

Sometimes Tenormin can cause delayed or long-term side effects. Some are considered mild, such as hair loss or purple-colored spots under the skin. 

Other long-term or delayed side effects are considered moderate, such as depression, orthostatic hypotension, diabetes, high triglycerides, impotence, penis injury, rash, plaque psoriasis, liver failure, and low platelet counts. 

Delayed or long-term side effects that are severe may include heart failure, pulmonary embolism (a clot that travels to the lungs, causing shortness of breath, chest pain, and cough), kidney failure, heart attack, lupus-like symptoms, and serum sickness (a reaction that can cause fever, rash, and joint pain).

Report Side Effects

Tenormin may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program online or by phone (800-332-1088).

Dosage: How Much Tenormin Should I Take?

Drug Content Provided and Reviewed by IBM Micromedex®


Potential users should note the following before starting treatment with Tenormin:

Children: Tenormin has not been studied for safety and efficacy in children, and is only approved in adults. However, some healthcare providers prescribe Tenormin off-label in children under close supervision. Off-label prescribing is when a drug is prescribed for something it is not officially approved to treat.

People who are pregnant: Atenolol can potentially harm a fetus at any time during pregnancy, especially in the second and third trimesters. Consult your healthcare provider if you are pregnant, become pregnant, or plan to become pregnant. If you already take atenolol and find out that you are pregnant, consult your healthcare provider right away. 

People who are nursing: Consult your healthcare provider if you are breastfeeding. In nursing people, atenolol can cause the baby to have low blood sugar and a slow heart rate. 

Adults 65 and older: The prescribing information advises that dosing should start on the low end in older adults because there is a higher chance of kidney, heart, or liver problems, as well as other medical conditions and medications that are being taken at the same time as atenolol. 

People with kidney problems: People with kidney problems will need to take a lower dose of Tenormin.

Missed Dose

If you miss a dose of Tenormin, take it as soon as you can. If it is almost time for the next dose, skip the missed dose. Do not take two doses together. 

Overdose: What Happens If I Take Too Much Tenormin

Taking too much Tenormin can cause symptoms of sleepiness, shortness of breath, wheezing, and bradycardia. It can also cause the heartbeat to pause or stop.

An overdose of Tenormin can also cause heart failure, hypotension, and/or hypoglycemia (low blood sugar). 

What Happens If I Overdose on Tenormin?

If you think you or someone else may have overdosed on Tenormin, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Tenormin, call 911 immediately.

What Are Reasons I Shouldn't Take Tenormin

Tenormin is not appropriate for everyone. Some people should not take Tenormin. 

You should not take Tenormin if you are allergic to atenolol or any of the inactive ingredients in Tenormin, or another beta-blocker. 

Other reasons you should not take Tenormin include:

  • Sinus bradycardia (a type of slow heartbeat)
  • Second-degree or third-degree atrioventricular (AV) block (when the signal that controls heartbeats is blocked, which can make the heart beat slowly or skip beats; can lead to dizziness, fainting, tiredness, and shortness of breath)
  • Worsening heart failure
  • Cardiogenic shock (a rare but life-threatening condition in which the heart cannot pump enough blood and oxygen to the body)
  • Sick sinus syndrome (when the heart’s natural pacemaker is damaged and cannot generate normal heartbeats) without a pacemaker
  • Untreated pheochromocytoma (an adrenal gland tumor)

People taking Tenormin should also avoid abrupt withdrawal from alcohol. 

 In other people, Tenormin may be prescribed with caution and close monitoring. Specifically, this includes people with lung disease, diabetes, thyroid disease, kidney problems, myasthenia gravis (weakness and fatigue of certain muscles), and older adults. Before taking Tenormin, tell your healthcare provider about all of your medical conditions and medical history.

What Other Medications Interact With Tenormin?

Before taking Tenormin, tell your healthcare provider about all of the medications you take, including prescription and over-the-counter (OTC) drugs, vitamins, and supplements.

Some drugs that interact with atenolol include:

Other beta-blockers that interact with atenolol include:

This is not a full list of drug interactions. Consult your healthcare provider for a full list of drug interactions.

What Medications Are Similar?

Tenormin is categorized as a beta-blocker.

Other drugs in the beta-blocker class of medications, which work in the same way and have similar uses and side effects, include:

Other medications to treat hypertension include:

This is a list of drugs also prescribed for blood pressure. It is not a list of drugs recommended to take with Tenormin. Ask your healthcare professional if you have questions.

Frequently Asked Questions

  • What is Tenormin used for?

    Tenormin is a beta-blocker that is used alone or with other medications to treat hypertension. It can also be used to prevent chest pain and increase survival after a heart attack.

  • How does Tenormin work?

    Tenormin works by relaxing blood vessels and slowing the heart rate, which helps to improve blood flow and lower blood pressure.

  • What drugs should not be taken with Tenormin?

    Before taking Tenormin, review your medication list with your healthcare provider. There are certain drugs that interact with Tenormin, for example, calcium channel blockers, indomethacin, digoxin, and other beta-blockers.

  • How long does it take for Tenormin to work?

    It may take up to several weeks to see the full effect of Tenormin. Continue to take Tenormin unless your healthcare provider tells you to stop.

  • How do I stop taking Tenormin?

    Your healthcare provider will advise you on how long to take Tenormin.

How Can I Stay Healthy While Taking Tenormin

Before taking Tenormin, discuss all medical conditions and your medical history with your healthcare provider. Tell your provider about all the medications you take. This helps ensure that Tenormin will be prescribed safely and that your healthcare provider can monitor you appropriately while taking Tenormin.

When taking Tenormin, follow your healthcare provider's instructions for use.

Talk to your healthcare provider about nondrug methods you can try, in addition to taking Tenormin, that can help lower your blood pressure. For example, if you smoke, talk to your healthcare provider about smoking cessation.

You can reduce salt in your diet, and ask your healthcare provider about following a diet such as the Dietary Approaches to Stop Hypertension (DASH) diet to help lower salt consumption and lose weight.

Also, ask your healthcare provider about what kind of exercise would be appropriate. Get an adequate amount of sleep and try to reduce stress. Limiting caffeine and alcohol is helpful, too. All of these things, in addition to taking Tenormin, can help lower your blood pressure and keep you healthier. 

High blood pressure generally does not cause any symptoms, so when you take Tenormin, you may not notice anything different.

Continue taking Tenormin unless your healthcare provider tells you to stop, or if you have severe side effects (in that case, consult your healthcare provider).

If you have trouble remembering to take Tenormin, try using a pill organizer to organize your medicines, and/or a phone app or alarm to remind you when to take your medicine.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. National Cancer Institute. Beta-blocker.

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By Karen Berger, PharmD
Karen Berger, PharmD, is a community pharmacist and medical writer/reviewer.