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What is atenolol?

Atenolol is a blood pressure medication in a group known as beta-blockers. It treats high blood pressure, irregular heartbeats, and chest pain caused by angina. Atenolol, also known by its brand name Tenormin, is sometimes prescribed to prevent migraines and help with anxiety.

Atenolol is only available by prescription, and it comes in tablet form that you swallow.

What does atenolol treat?

Atenolol is a beta-blocker that affects your heart and circulation (blood flow through arteries and veins). Beta-blockers work by blocking the effects of the hormone epinephrine, also known as adrenaline.

Atenolol treats the following:

  • Angina (chest pain)

  • Hypertension (high blood pressure)

  • Also used to lower the risk of fatality following a heart attack

How do you take atenolol?

Atenolol can make you feel dizzy, sick, tired, or give you constipation or diarrhea. However, these side effects are typically mild and temporary.

Your first dose of atenolol could make you feel dizzy, so you should usually take it before bedtime. Once you no longer feel dizzy, you can take it at any time.

You should never stop taking atenolol suddenly, especially if you have a heart condition. This can make your condition worse. Instead, contact your doctor before stopping your medication.

Atenolol is available as a generic drug under the brand name Tenormin. It’s available in tablet form in 25, 50, and 100mg. It’s also available as an oral solution at 5mg/ml, and injection at 0.5mg/ml.

Potential side effects of atenolol

Like all medicines, atenolol can cause side effects in some people. However, these side effects are usually mild and short-lived and often improve as your body gets used to the medicine.

Common side effects

  • Feeling sleepy, tired, or dizzy

  • Cold feeling in your fingers or toes

  • Feeling sick (nausea)

  • Diarrhea

  • Constipation

Serious side effects

In rare cases, some people have serious adverse effects after taking atenolol. You should contact your physician right away if you experience the following:

  • Blurred vision

  • Confusion

  • Dizziness, faintness, or lightheadedness when getting up from a lying position

Long-term use of atenolol

There is limited information on the long-term effects of atenolol. However, studies have shown that you can safely use atenolol for up to ten years.

Missed doses

If you forget to take a dose of atenolol, you should take it immediately unless it's nearly time for the next dose. In this case, skip the missed dose and take the next one as normal.

You should never take two doses at the same time¹. Do not take an extra dose to compensate for the missed one.

If you forget your doses often, set an alarm to remind you. You can also contact your pharmacist for advice on how you can best remind yourself to take your medicine.


If you overdose on atenolol (Tenormin), call Poison Control at 1-800-222-1222 or immediately go to the nearest emergency room.

Symptoms of atenolol overdose may include:

  • Drowsiness

  • Severe dizziness

  • Slow heartbeat

  • Fainting

  • Weakness

  • Shortness of breath

  • Coma

What to discuss with your doctor before you start taking atenolol

If you have any of the following, discuss them with your doctor before starting atenolol:

  • Asthma or other respiratory problems 

  • Severe allergies 

  • Liver disease 

  • A thyroid disorder

  • Kidney disease

  • Diabetes

  • Coronary artery disease

  • Pheochromocytoma

  • An irregular heartbeat

Atenolol may raise or lower your blood sugar level, which could mask the symptoms of low blood sugar. If you have diabetes or a similar disease, report any blood sugar level changes to your physician.

Furthermore, some medicines can affect how atenolol works. Discuss with your doctor if you are using one of the following medications:

  • Amiodarone

  • Clonidine

  • Disopyramide

  • Indomethacin

  • Reserpine

  • Verapamil

  • Diltiazem

You should inform your health professional if you are pregnant or breastfeeding, as atenolol may potentially harm an unborn or breastfeeding baby.

Stopping atenolol suddenly

If you're suffering from heart disease, you should not stop taking atenolol suddenly without consulting your doctor. Suddenly stopping atenolol can make your condition worse.

Atenolol and pregnancy

It is not safe to take atenolol during pregnancy as it could harm the fetus. Inform your health professional immediately if you become pregnant while taking Tenormin. Atenolol can pass into breast milk, potentially harming a nursing baby.

Interactions with other drugs

You shouldn’t take certain medicines together to prevent unwanted drug interactions or adverse effects. However, there are certain instances where you may need to take different drugs together, even if an interaction might occur. In this case, your physician may want to change the dose of the drugs, and other precautions may be necessary.

When you take atenolol (Tenormin), your doctor must know if you are taking any of the medicines listed below:

  • Albuterol

  • Ceritinib

  • Clonidine

  • Crizotinib

  • Diltiazem

  • Dronedarone

  • Fenoldopam

  • Fingolimod

  • Formoterol

  • Indacaterol

  • Iohexol

  • Lacosamide

  • Levalbuterol

  • Olodaterol

  • Ponesimod

  • Rivastigmine

  • Salmeterol

  • Siponimod

  • Terbutaline

  • Verapamil

  • Vilanterol

Allergy information

Beta-blockers are not commonly associated with allergic reactions, but they may aggravate the risk of anaphylaxis from other causes.

Atenolol may cause:

  • Skin rashes, including lichenoid eruptions

  • Drug-induced lupus

  • Aggravation of pre-existing systemic lupus erythematosus (SLE)

  • Exacerbation of Raynaud's syndrome

  • Photosensitivity

The extent of cross-reactivity among multiple beta-blockers is not well-specified in any case study. Large case-control research of beta-blocker hypersensitivity reactions described 2.4 reactions per 1000 patient-years of beta-blocker use. There was no increase in atenolol reactions compared to other beta-blockers.

Moreover, the risk of allergy was increased in women and decreased in those older than 65 years. Studies identified no specific elevated risk for atenolol reactions in prior beta-blocker reactors.

Patients with known hypersensitivity to Tenormin or other beta-blockers should use it with caution. If a rash develops², you should discontinue atenolol and seek medical attention.

Clinical trial history

The FDA first approved atenolol in 1981³. Several clinical trials have studied atenolol for treating hypertension, angina pectoris, and heart failure.

Tips and advice for taking atenolol

In addition to taking atenolol, high blood pressure treatment usually includes lifestyle changes, particularly weight control and diet. Before taking atenolol, your doctor will advise you on other changes, including modifying your food intake and reducing your sodium consumption.

Many people with high blood pressure do not feel any symptoms. They may look and feel normal. You must follow your doctor's directions when taking atenolol and keep regular appointments even if you feel well. This will ensure your blood pressure is under control and you are taking the correct dosage.

Atenolol will not cure your high blood pressure; it helps you manage it. You must continue to take atenolol as directed by your physician to maintain normal blood pressure. You may also have to take blood pressure medicine for life. High blood pressure can cause serious problems such as heart failure, blood vessel disease, stroke, or kidney disease if not treated properly.

You should never interrupt or stop taking atenolol without consulting with your doctor. They may want you to gradually reduce the amount you take before stopping it completely. This prevents certain conditions from worsening if you stop taking the medicine suddenly.

  1. Atenolol | NHS

  2. Beta blocker allergy | American Academy of Allergy Asthma & Immunology

  3. Atenolol | Drugbank Online

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Here at HealthMatch, we’ve done our best to ensure that the information provided in this article is helpful, up to date, and, most importantly, accurate.

However, we can’t replace the one-to-one advice of a qualified medical practitioner or outline all of the possible risks associated with this particular drug and your circumstances.

It is therefore important for you to note that the information contained in this article does not constitute professional medical or healthcare advice, diagnosis or recommendation of treatment and is not intended to, nor should be used to, replace professional medical advice. This article may not always be up to date and is not exhaustive of all of the risks and considerations relevant to this particular drug. In no circumstances should this article be relied upon without independent consideration and confirmation by a qualified medical practitioner.

Your doctor will be able to explain all possible uses, dosages, precautions, interactions with other drugs, and other potential adverse effects, and you should always talk to them about any kind of medication you are taking, thinking about taking or wanting to stop taking.

Curious about clinical trials?

Access the latest treatments and medications. unavailable elsewhere - entirely free of charge. We make it easy to take part.