- Atenolol slows down your heart rate and makes it easier for your heart to pump blood around your body.
- It can make you feel dizzy, sick or tired, or give you constipation or diarrhoea. These side effects are usually mild and short-lived.
- Your very first dose of atenolol may make you feel dizzy, so take it at bedtime. After that, if you do not feel dizzy, you can take it in the morning.
- Do not stop taking atenolol suddenly, especially if you have heart disease. This can make your condition worse.
- Atenolol is known by the brand name Tenormin. Other brand names include Tenif (for atenolol mixed with nifedipine) and Co-tenidone (atenolol mixed with chlortalidone).
Atenolol can be taken by adults. It's sometimes also prescribed for babies and children.
It's not suitable for everyone. To make sure it's safe for you, tell your doctor before starting atenolol if you have:
- had an allergic reaction to atenolol or any other medicine in the past
- low blood pressure or a slow heart rate
- serious blood circulation problems in your limbs (such as Raynaud's phenomenon), which may make your fingers and toes tingle or turn pale or blue
- metabolic acidosis - when there's too much acid in your blood
- lung disease or asthma
Tell your doctor if you're trying to get pregnant, are already pregnant or breastfeeding.
You'll usually take atenolol once or twice a day.
When you start taking atenolol, your doctor may advise you to take your first dose before bedtime because it can make you feel dizzy.
After the first dose, if you do not feel dizzy, you can take your medicine in the morning.
If you're taking atenolol twice a day, you'll usually have 1 dose in the morning and 1 dose in the evening.
It's a good idea to leave 10 to 12 hours between doses if you can.
Do not stop taking atenolol suddenly, especially if you have heart disease. This can make your condition worse.
If you want to stop taking your medicine, speak to your doctor. They may recommended reducing your dose gradually over a few weeks.
How much will I take?
How much you take depends on why you need atenolol.
- For high blood pressure - the usual dose is 25mg to 50mg taken once a day.
- For angina (chest pain) - the usual dose is 100mg taken once a day, or split into 2 50mg doses.
- For irregular heartbeats (arrhythmia) - the usual dose is 50mg to 100mg taken once a day.
- For migraine - the usual dose is 25mg to 100mg taken twice a day. Doctors sometimes prescribe atenolol for migraine, but it's not officially approved for preventing it.
For children taking atenolol, your child's doctor will work out the right dose by using their weight and age.
How to take it
Atenolol does not usually upset your tummy, so you can take it with or without food. It's best to do the same each day.
Swallow the tablets whole with a drink of water.
If you find them difficult to swallow, some brands have a score line to help you break the tablet in half. Check the information leaflet for your brand to see if you can do this.
If you're taking atenolol as a liquid, it'll come with a plastic syringe or spoon to help you measure out the right dose.
If you do not have one, ask your pharmacist for one. Do not use a kitchen teaspoon as it will not give you the right amount of medicine.
What if I forget to take it?
If you forget to take a dose of atenolol, take it as soon as you remember, unless it's nearly time for your next dose. In this case, just leave out the missed dose and take your next dose as normal.
Never take 2 doses at the same time. Do not take an extra dose to make up for a forgotten one.
If you often forget doses, it may help to set an alarm to remind you.
You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.
What if I take too much?
The amount of atenolol that can lead to an overdose varies from person to person.
Call your doctor or go to A&E straight away if you take too much atenolol
If you take more than the prescribed dose, your heart rate may slow down and you may find it difficult to breathe. It can also cause dizziness and trembling.
If you need to go to hospital, do not drive yourself. Get someone else to drive you or call for an ambulance.
Take the atenolol packet or leaflet inside it, plus any remaining medicine, with you.
Like all medicines, atenolol can cause side effects in some people, but many people have no side effects or only minor ones.
Side effects often improve as your body gets used to the medicine.
Common side effects
These common side effects happen in more than 1 in 100 people. They're usually mild and short-lived.
Talk to your doctor or pharmacist if these side effects bother you or last more than a few days:
- feeling sleepy, tired or dizzy
- cold fingers or toes
- feeling sick (nausea)
Serious side effects
It happens rarely, but some people have serious side effects when taking atenolol.
Tell a doctor straight away if you have:
- shortness of breath with a cough that gets worse when you exercise (like walking up stairs), swollen ankles or legs, chest pain, or an irregular heartbeat - these can be signs of heart problems
- trouble breathing, cold sweats and sudden, sharp chest pain that gets worse when you cough or take deep breaths - these can be signs of lung problems
- a fast heart rate, a high temperature, trembling and confusion - these can be signs of a thyroid problem
Serious allergic reaction
In rare cases, atenolol may cause a serious allergic reaction (anaphylaxis).
Call 999 or go to A&E if:
- you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
- you're wheezing
- you get tightness in the chest or throat
- you have trouble breathing or talking
- your mouth, face, lips, tongue or throat start swelling
You could be having a serious allergic reaction and may need immediate treatment in hospital.
These are not all the side effects of atenolol.
For a full list, see the leaflet inside your medicine packet.
You can report any suspected side effect to the UK safety scheme.
What to do about:
- feeling sleepy, tired or dizzy - as your body gets used to atenolol, these side effects should wear off. If atenolol makes you feel dizzy, sit or lie down until you feel better. Do not drive or operate machinery until you feel OK again. Try to avoid alcohol as it'll make you feel worse.
- cold fingers or toes - put your hands or feet under warm running water, massage them and wiggle your fingers and toes. Do not smoke or have drinks with caffeine in - this can make your blood vessels narrower and further restrict blood flow to your hands and feet. Try wearing mittens (they're warmer than gloves) and warm socks. Do not wear tight watches or bracelets.
- feeling sick (nausea) - stick to simple meals and do not eat rich or spicy food. It might help to take your atenolol after a meal or snack.
- diarrhoea - drink lots of fluids, such as water or squash, to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
- constipation - eat more high-fibre foods, such as fresh fruit, vegetables and cereals, and drink plenty of water. Try to exercise more regularly by going for a daily walk, for example. If this does not help, talk to your pharmacist or doctor. Watch this short video about how to treat constipation
Atenolol is not usually recommended in pregnancy.
If you're trying to get pregnant or already pregnant, talk to your doctor about the benefits and possible harms of taking atenolol.
There may be other medicines that are safer for you. Labetalol is a similar medicine that's often recommended for high blood pressure in pregnancy.
For more information about how atenolol can affect you and your baby during pregnancy, visit the best use of medicines in pregnancy (BUMPS) website.
Atenolol and breastfeeding
If your doctor or health visitor says that your baby's healthy, it's OK to take atenolol while breastfeeding.
Atenolol passes into breast milk in small amounts, and it's unlikely to cause any side effects in your baby.
It's important to treat your high blood pressure to keep you well. Breastfeeding will also benefit both you and your baby.
If your baby's not feeding as well as usual or seems unusually sleepy, or you have any other concerns about them, talk to your doctor or health visitor.
They may recommend a different medicine for your blood pressure.
Tell your doctor if you're:
- trying to get pregnant
There are some medicines that may interfere with the way atenolol works.
Tell your doctor if you're taking:
- other medicines for high blood pressure - the combination with atenolol can sometimes lower your blood pressure too much, which may make you feel dizzy or faint; tell your doctor if this keeps happening to you, as they may change your dose
- other medicines for an irregular heartbeat, such as amiodarone or flecainide
- medicines for asthma or chronic obstructive pulmonary disease (COPD)
- medicines for diabetes, particularly insulin - atenolol may make it more difficult to recognise the warning signs of low blood sugar; speak to your doctor if you have low blood sugar levels without getting any of the usual warning signs (you should check your blood sugar after exercise and follow the usual advice about checking it before driving or operating machinery)
- medicines to treat nose or sinus congestion, or other cold remedies (including those you can buy in a pharmacy)
- medicines for allergies, such as ephedrine, noradrenaline or adrenaline
Mixing atenolol with herbal remedies or supplements
There's very little information about taking herbal remedies and supplements with atenolol.
For safety, tell your doctor or pharmacist if you're taking any other medicines, including herbal medicines, vitamins or supplements.
How does atenolol work?
Atenolol is a type of medicine called a beta blocker.
Like other beta blockers, atenolol works by changing the way your body responds to some nerve impulses, including in the heart.
It slows down your heart rate and makes it easier for your heart to pump blood around your body.
We do not fully understand how atenolol prevents migraines.
It may work by relaxing the blood vessels involved or by reducing activity in the visual cortex. This is the part of the brain where migraines are believed to start.
How long does atenolol take to work?
Atenolol starts to work after about 3 hours to reduce high blood pressure, but it can take up to 2 weeks to reach its full effect.
You may not feel any different when you take atenolol for high blood pressure, but this does not mean it's not working. It's important to keep taking your medicine.
For migraines, it may take several weeks for atenolol to start making a real difference, so keep taking it.
How long will I take it for?
This depends on why you're taking atenolol.
For heart conditions or high blood pressure - treatment is usually long term and may be for the rest of your life.
For migraines - treatment can last for several months or years, depending on how bad your symptoms are.
Is it safe to take for a long time?
Atenolol is generally safe to take for a long time.
If you're taking it for a heart condition or to prevent migraines, it works best when you take it long term.
You'll need to have your blood pressure checked regularly if you're taking atenolol for a long time for migraines.
What will happen if I stop taking it?
Talk to your doctor if you want to stop taking atenolol.
Stopping atenolol suddenly may make your health problem worse.
If you're bothered by side effects, your doctor may be able to prescribe a different medicine instead.
If you stop taking atenolol, it'll take about 1 to 2 days for it to be completely out of your body.
How does atenolol compare with other heart medicines?
Atenolol works as well as other beta blockers for reducing blood pressure.
But it's less likely to cause side effects because it works mainly on the heart.
Other beta blockers, like propranolol, work on your heart and affect other parts of your body, too.
There are lots of other medicines to lower your blood pressure and treat chest pain.
They work in a different way from beta blockers and include:
- ACE inhibitors - for example, ramipril and lisinopril
- angiotensin receptor blockers - for example, candesartan
- calcium channel blockers - for example, amlodipine
- diuretics (medicines that make you pee more) - for example, furosemide
Beta blockers are not usually the first choice treatment for high blood pressure.
The medicine your doctor prescribes depends on your age and ethnicity.
If you're under 55, you'll usually be offered an ACE inhibitor or an angiotensin receptor blocker.
If you're 55 or older, or you're any age and of African Caribbean or black African origin, you'll usually be offered a calcium channel blocker.
Sometimes you may have to try other blood pressure-lowering medicines if you get side effects.
Many people need to take a combination of different blood pressure-lowering tablets.
How does it compare with other medicines for preventing migraine?
There are some other medicines that are known to prevent migraines, but they're not officially approved in the UK.
Topiramate can also be used to prevent migraines. But topiramate has not been officially approved for migraine for children under the age of 16.
Ask your doctor or pharmacist which medicine is best for you.
Will I need to stop atenolol before surgery?
Tell your doctor that you're taking atenolol if you're going to be put to sleep (using general anaesthetic) or you're having any kind of major operation.
Your doctor may advise you to stop taking atenolol for 24 hours before surgery.
This is because atenolol can lower your blood pressure too much when it's combined with some anaesthetics.
Can I drink alcohol with it?
Drinking alcohol can increase the blood pressure-lowering effect of atenolol, which can make you feel dizzy or lightheaded.
During the first few days of taking atenolol or after an increase in your dose, it's best to stop drinking alcohol until you see how the medicine affects you.
If you find atenolol makes you feel dizzy, it's best to stop drinking alcohol.
Is there any food or drink I need to avoid?
You can eat and drink normally while taking atenolol.
Will it affect my contraception?
Atenolol will not stop your contraception working.
Talk to your doctor if you're taking a hormonal contraceptive.
Will it affect my fertility?
It's unlikely that atenolol affects fertility in men or women. But there's not enough evidence to say for certain.
If you're trying for a baby or having problems getting pregnant while on atenolol, speak to your doctor.
Will it affect my sex life?
Some people on atenolol say their sex drive goes down, and some men find they cannot get an erection.
But this is not a common side effect and there's not enough evidence to say for sure that atenolol is causing it.
If you're having problems with your sex life, talk to your doctor.
Do I need to avoid playing sports?
You do not need to stop playing sports if you take atenolol. But do not push yourself too much.
Regular exercise is good for you because it lowers blood pressure by keeping your heart and blood vessels in good condition.
Be aware, though, that in some sports atenolol is not allowed if you're competing at a high level.
Can I drive or ride a bike?
Atenolol can make some people feel dizzy, especially when you first start taking it or after taking a bigger dose.
If this happens to you, do not drive a car, ride a bike, or use tools or machinery until you feel better.
Can lifestyle changes help with high blood pressure?
If you have heart problems, you can boost the health of your heart by making some key lifestyle changes.
These will also help if you have high blood pressure.
- Quit smoking - smoking increases your heart rate and blood pressure. Quitting smoking brings down your blood pressure and relieves heart failure symptoms. Try to avoid secondhand smoke.
- Cut down on alcohol - drinking alcohol while you're taking atenolol can make you feel dizzy or lightheaded. Also, drinking too much alcohol raises blood pressure over time and makes heart failure worse. Men and women should not drink more than 14 units of alcohol a week. A standard glass of wine (175ml) is 2 units. A pint of lager or beer is usually 2 to 3 units of alcohol.
- Exercise - regular exercise lowers blood pressure by keeping your heart and blood vessels in good condition. It does not need to be too energetic: walking every day will help.
- Eat well - aim to eat a diet that includes plenty of fruit and veg, wholegrains, fat-free or low-fat dairy products and lean proteins. It's a good idea to cut down on salt, too. Eating too much salt is the biggest cause of high blood pressure. The more salt you eat, the higher your blood pressure will be. Aim for no more than 6g of salt a day.
- Deal with stress - when you're anxious or upset, your heart beats faster, you breathe more heavily and your blood pressure often goes up. This can make heart failure worse, too. Find ways to reduce stress in your life. To give your heart a rest, try napping or putting your feet up when possible. Spend time with friends and family to be social and help avoid stress.
Can lifestyle changes help with migraines?
There are a number of things you can do to help prevent migraines.
This includes working out what things trigger an attack so you can avoid them.
Keeping a migraine diary may help you do this.