This is a combination product that contains two medications, atenolol and chlorthalidone. It is used to treat high blood pressure. Atenolol is a beta-blocker that works by decreasing the workload of the heart. Chlorthalidone is a diuretic (water pill) that helps to eliminate excess salt and water from the body.

It is very important that this medication be taken regularly and exactly as prescribed by the doctor. Do not stop taking this medication without first talking with your doctor.

More common:
decreased sexual ability
dizziness or lightheadedness
drowsiness (mild)
trouble in sleeping
Less common:
anxiety or nervousness
constipation
diarrhea
increased sensitivity of skin to sunlight (skin rash, itching, redness or other discolouration of skin, or severe sunburn)
loss of appetite
numbness or tingling in the fingers and toes
stomach discomfort or upset
stuffy nose
Rare:
changes in taste
dry, sore eyes
itching of the skin
nightmares and vivid dreams

Check with your doctor as soon as possible if any of the following side effects occur:
Less common:
breathing difficulty or wheezing
cold hands and feet
depression
slow heartbeat (especially less than 50 beats per minute)
swelling of the ankles, feet, or lower legs
Rare:
black, tarry stools
blood in the urine or stools
chest pain
dark urine
fever, chills, cough, or sore throat
hallucinations
joint pain
lower back or side pain
pinpoint red spots on the skin
red, scaling, or crusted skin
skin rash or hives
stomach pain (severe) with nausea and vomiting
unusual bleeding or bruising
yellow eyes or skin

There may be an interaction between atenolol - chlorthalidone and any of the following:
alcohol
amlodipine
anesthetic agents
anticholinergics (e.g., atropine, hyoscyamine)
antidiabetic agents (e.g., insulin)
asthma medications (e.g., theophylline)
barbiturates (e.g., phenobarbital)
clonidine
digoxin
diltiazem
disopyramide
epinephrine
felodipine
flecainide
guanethidine
lidocaine
lithim
mexiletene
monoamine oxidase (MAO) inhibitors (e.g., tranylcypromine, phenelzine) taken within the past 2 weeks
narcotic analgesics (e.g., morphine, codeine)
nifedipine
nonsteroidal anti-inflammatory drugs (e.g., ibuprofen)
norepinephrine
other beta-blockers (e.g., propranolol, metoprolol)
procainamide
propafenone
quinidine
reserpine
salicylates (e.g., ASA, salsalate)
tubocurarine
verapamil
If you are taking any medications containing these drugs, speak with your doctor.

Check with your doctor immediately if any of the following signs of overdose occur:
slow heartbeat
dizziness (severe) or fainting
difficulty in breathing
bluish-coloured fingernails or palms of the hands
convulsions

Do not stop taking this medication suddenly without checking with your doctor first. Stopping this medication suddenly after you have been taking it for a while may cause unpleasant and potentially harmful side effects.

If you miss a dose, take it as soon as possible and continue on with your regular schedule. If it is within eight hours of your next dose, skip the missed dose and continue on with your regular dosing schedule. Do not take a double dose to make up for a missed one.

This product is used to treat high blood pressure.

Store at room temperature between 68-77 degrees F (20-25 degrees C) away from heat and moisture.

Atenolol - chlorthalidone should not be taken by people who:

are allergic to atenolol, chlorthalidone or to any ingredients of the medication
are allergic to sulfa medications (e.g. sulfamethoxazole)
have a severely slow heart rate
have a serious heart block
have congestive heart failure
are not able to expel urine
have very low blood pressure
have severe peripheral arterial disorders (blockage of blood flow to limbs of body)
have a condition known as pheochromocytoma (in the absence of alpha-blockade)
have metabolic acidosis
have a condition known as right ventricular failure caused by pulmonary hypertension
have a condition known as "sick sinus syndrome"