Patient leaflet - Co-tenidone 100/25 mg film-coated tablets
1. What Co-tenidone Tablets are and what they are used for
Co-Tenidone tablets are available in two different strengths and your doctor will have decided which is the most suitable for you. Co-tenidone 50/12.5 mg Tablets contain 50 mg of atenolol and 12.5 mg of chlortalidone as the active ingredients. Co-tenidone 100/25 mg Tablets contain 100 mg of atenolol and 25 mg of chlortalidone as the active ingredients. Co-tenidone is used to treat high blood pressure (hypertension). These medicines work together to lower your blood pressure.
- Atenolol belongs to a group of medicines known as beta blockers which work by making your heart beat more slowly and with less force.
- Chlortalidone belongs to a group of medicines known as diuretics, which work by increasing the amount of urine produced by your kidneys.
2. What you need to know before you take Co-tenidone Tablets
Do not take Co-Tenidone tablets:
- If you are allergic to atenolol, chlortalidone or to any of the other ingredients (these are listed in section 6).
If you have ever had any of the following heart problems:
- heart failure which is not under control (this usually makes you breathless and causes your ankles to swell)
- second- or third-degree heart block (a condition which may be treated by a pacemaker)
- very slow or very uneven heart beats, very low blood pressure or very poor circulation.
- If you have problems with your kidneys.
- If you have a tumour called phaeochromocytoma that is not being treated. This is usually near your kidney and can cause high blood pressure.
- If you have been told that you have higher than normal levels of acid in your blood (metabolic acidosis).
- If you are pregnant, are trying to become pregnant or are breast-feeding.
Do not take Co-Tenidone if any of the above apply to you. If you are not sure, talk to your doctor or pharmacist before taking Co-Tenidone.
Warnings and precautions:
Talk to your doctor or pharmacist before taking Co-Tenidone Tablets:
If you have asthma, wheezing or any other similar breathing problems, or you get allergic reactions, for
example to insect stings. If you have ever had asthma or wheezing, do not take this medicine without first checking with your doctor.
- If you have a type of chest pain (angina) called Prinzmetal's angina.
- If you have poor blood circulation or controlled heart failure.
- If you have first-degree heart block.
- If you have diabetes. Your medicine may change how you respond to having low blood sugar. You may feel your heart beating faster. Atenolol could also increase the risk of severe hypoglycaemia when used with certain type of antidiabetic drugs called sulfonylureas (e.g. gliquidone, gliclazide, glibenclamide, glipizide, glimepiride or tolbutamide)
- If you have thyrotoxicosis (a condition caused by an overactive thyroid gland). Your medicine may hide the symptoms of thyrotoxicosis.
- If you have problems with your adrenal glands.
- If you have liver problems.
- If you experience a decrease in vision or eye pain. These could be symptoms of fluid accumulation in the vascular layer of the eye (choroidal effusion) or an increase of pressure in your eye and can happen within hours to a week of taking Co-Tenidone Tablets. This can lead to permanent vision loss, if not treated. If you earlier have had a penicillin or sulfonamide allergy, you can be at higher risk of developing this.
If you are not sure if any of the above apply to you, talk to your doctor or pharmacist before taking Co-Tenidone Tablets. Children
This medicine is not for use in children.
Other medicines and Co-Tenidone
Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines. This includes medicines that you buy without a prescription and herbal medicines. This is because Co-Tenidone can affect the way some other medicines work and some medicines can have an effect on Co-Tenidone.
In particular, tell your doctor if you are taking any of the following medicines:
- Clonidine (for high blood pressure or migraine). If you are taking clonidine and Co-Tenidone together, do not stop taking clonidine unless your doctor tells you to do so. If you have to stop taking clonidine, your doctor will give you careful instructions about how to do it.
- Verapamil, diltiazem and nifedipine (for high blood pressure or chest pain).
- Disopyramide or amiodarone (for an uneven heart beat).
- Digoxin (for heart problems).
- Adrenaline, also known as epinephrine (a medicine that stimulates the heart).
- Baclofen (a medicine used for muscle relaxation).
- Ibuprofen or indometacin (for pain and inflammation).
- Insulin or medicines that you take by mouth for diabetes such as drugs called sulfonylureas (e.g. gliquidone, gliclazide, glibenclamide, glipizide, glimepiride or tolbutamide)
- Lithium (for certain mental illnesses).
- Medicines to treat nose or sinus congestion or other cold remedies (including those you can buy in the pharmacy).
- Betaxolol, carteolol, levobunolol and timolol (eye drops for glaucoma).
Operations
If you go into hospital to have an operation, tell the anaesthetist or medical staff that you are taking Co-Tenidone. This is because you can get low blood pressure (hypotension) if you are given certain anaesthetics while you are taking Co-Tenidone.
Pregnancy and breast-feeding
- Do not take Co-Tenidone if you are pregnant or trying to get pregnant, ask your doctor for advice before using this medicine.
Do not take Co-Tenidone if you are breast-feeding, ask your doctor for advice before using this medicine. Driving and using machines
- Your medicine is not likely to affect you being able to drive or use any tools or machines. However, it is best to wait to see how your medicine affects you before trying these activities.
If you feel dizzy or tired when taking this medicine, ask your doctor for advice.
Co-tenidone contains sodium laurilsulfate.
This medicine contains less than 1 mmol sodium (23 mg) per tablet, that it is to say essentially ‘sodium-free’.
3. How to take Co-tenidone Tablets
Always take this medicine exactly as your doctor or pharmacist has told you. Check with your doctor or pharmacist if you are not sure.
- Your doctor will tell you how many tablets to take each day and when to take them. Read the label on the carton to remind you what the doctor said.
- Swallow your tablet with a drink of water
Adults:
The recommended dose for an adult is one tablet daily. Children: Your medicine must not be given to children. People with kidney problems
If you have problems with your kidneys, your doctor may give you a lower dose or ask you to take this medicine less often. If you take more tablets than you should
If you take more Co-Tenidone tablets than prescribed by your doctor, talk to a doctor or go to a hospital straight away. Take the medicine pack with you so that the tablets can be identified. If you forget to take a dose of Co-tenidone Tablets
If you forget to take a dose, take it as soon as you remember. However, if it is almost time for the next dose, skip the missed dose. Do not take a double dose to make up for a forgotten dose.
If you stop taking Co-Tenidone
Do not stop taking Co-Tenidone without talking to your doctor. In some cases, you may need to stop taking it gradually. If you have any further questions on the use of this medicine, ask your doctor or pharmacist.
4. Possible side effects
Like all medicines, Co-Tenidone tablets can cause side effects, although not everybody gets them.
- Allergic reactions: If you have an allergic reaction, see a doctor straight away. The signs may include raised lumps on your skin (weals) or swelling of your face, lips, mouth, tongue or throat.
Other possible side effects:
Common (may affect up to 1 in 10 people)
- Cold hands and feet.
- You may notice that your pulse rate becomes slower while you are taking the tablets. This is normal, but if you are concerned please tell your doctor about it.
- Diarrhoea.
- Feeling sick (nausea).
- Feeling tired.
Changes in the amount of certain substances in your blood. It can cause:
- higher levels of sugar (glucose) than normal
- low levels of sodium, which may cause weakness, being sick (vomiting) and cramps
- low levels of potassium, - an increase in the amount of uric acid.
Your doctor may take blood samples every so often to check on these levels.
Uncommon (may affect up to 1 in 100 people)
- Disturbed sleep.
Rare (may affect up to 1 in 1,000 people)
- Heart block (which can cause an abnormal heart beat, dizziness, tiredness or fainting).
- Numbness and spasm in your fingers which is followed by warmth and pain (Raynaud’s disease).
- Dizziness (particularly when standing up).
- Headache.
- Feeling confused.
- Changes in personality (psychoses) or hallucinations.
- Mood changes.
- Nightmares.
- Dry mouth.
- Thinning of your hair.
- Dry eyes.
- Skin rash.
- Tingling of your hands.
Disturbances of vision.
- Bruising more easily or purplish marks on your skin.
- Being unable to get an erection (impotence).
- Jaundice (causing yellowing of your skin or the whites of your eyes).
- Pancreatitis (inflammation of a large gland behind the stomach).
- A reduced number of white blood cells.
Very rare (may affect up to 1 in 10,000 people)
- Changes to some of the cells or other parts of your blood. Your doctor may take blood samples every so often to check whether Co-Tenidone tablets has had any effect on your blood.
Not known (frequency cannot be estimated from the available data)
- Depression.
- Constipation.
- Lupus-like syndrome (a disease where the immune system produces antibodies that attacks mainly skin and joints).
- Decrease in vision or pain in your eyes due to high pressure (possible signs of fluid accumulation in the vascular layer of the eye (choroidal effusion) or acute angle-closure glaucoma)
Conditions that may get worse
If you have any of the following conditions, they may get worse when you start to take your medicine. This happens rarely affecting less than 1 in 1,000 people:
- Psoriasis (a skin condition).
- Being short of breath or having swollen ankles (if you have heart failure).
- Asthma or breathing problems.
- Poor circulation.
Reporting side effects
If you get any side effects, talk to your doctor or pharmacist. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme Website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine
5. How to store Co-tenidone Tablets
- Keep this medicine out of the sight and reach of children.Your medicine could harm them.
- Do not use your tablets after the expiry date which is stated on the blister strip and carton. The expiry date refers to the last day of the month.
- Do not store above 25°C. Store your tablets in the original package. Keep the blister strip in the carton.This will protect your medicine from light and moisture. Do not throw away any medicine via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help protect the environment.
6. Contents of the pack and other information
What Co-Tenidone tablets contain
The active substances are atenolol and chlortalidone. Co-tenidone 50/12.5 mg Tablets contain 50 mg (milligrams) of atenolol and 12.5 mg of chlortalidone.
Co-tenidone 100/25 mg Tablets contain 100 mg (milligrams) of atenolol and 25 mg of chlortalidone.
The other ingredients are magnesium carbonate (heavy), maize starch, sodium laurilsulfate, gelatin, magnesium stearate, hypromellose, titanium dioxide (E171), ethylcellulose and diethyl phthalate.
What Co-Tenidone looks like and the contents of the pack.
The 50/12.5 mg tablets are round, white, film-coated tablets and the 100/25mg tablets are round, white, film-coated tablets with a break-line.
They are supplied to your pharmacist in packs containing 28, 56, 84, 112, 140, 168, 196, 224, 252 or 280 tablets. Not all pack sizes may be available.
Marketing Authoristion Holder
RxFarma, Colonial Way, Watford, Hertfordshire, WD24 4YR Manufacturer: Rx Farma Limited, Unit 3, Colonial Way, Watford, Hertfordshire, WD24 4YR, United Kingdom Date of revision: December 2025
If you would like this leaflet in a different format, please contact the MA holder at the above address.