Chlorothiazide is used together with other medicines to treat water retention caused by heart failure (weakness and inability of the heart to pump blood) and kidney or liver disease. Water retention may be noticed as swelling of the feet, ankles, lower leg and hands, or shortness of breath. For this reason, it is commonly known as a "water pill".
This medicine may also be used on its own or together with other medicines to help keep your blood pressure under control.
Take Chlorothiazide exactly as directed by your doctor or according to the instructions on the label. Do not take more or less than instructed by your doctor.
You may need to pass urine more often while being treated with Chlorothiazide. Take this medicine early in the day, preferably in the morning. If your doctor has told you to take it twice a day, take the last dose in the late afternoon. This is to prevent you from waking up frequently at night to go to the toilet. Try to take it at the same time each day.
This medicine is available as an oral suspension. Shake the bottle well before you take the medicine to ensure that the liquid is evenly mixed. Use the measuring spoon or cup provided to measure your dose.
The dose of this medicine will be decided by your doctor. Your doctor will advise you on the treatment timeframe depending on your response to the medication.
Chlorothiazide must be taken regularly for it to be effective. Continue taking this medicine even when you feel better. Do not stop taking it unless instructed by the doctor.
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and return to your normal dosing schedule.
DO NOT double a dose under any circumstances.
If you often forget to take your medicine, let your doctor and pharmacist know.
Do not take Chlorothiazide if you ever had an allergic reaction (e.g. rashes, breathlessness, swollen eyes) to a certain group of medicines called sulfonamides.
Alert your doctor if you have anuria (a condition wherein you are unable to pass urine) as this medicine may not be suitable for you.
Inform your doctor if you have the following conditions:
- gout (high uric acid level in the blood)
- prediabetes (a condition in which the blood sugar levels are higher than normal but not high enough to be diagnosed as diabetes) or diabetes
- moderate or high cholesterol level
- high calcium level in the blood
- low potassium level in the blood
- primary adrenal insufficiency (a rare disorder where the adrenal glands produce insufficient amounts of certain hormones)
- have undergone recent surgery on the nerves
- liver disease
- severe kidney disease
Let your doctor know if you are pregnant or breastfeeding.
Be sure to check with your doctor or pharmacist before giving Chlorothiazide to a child. Children may be more sensitive to the side effects.
If you are going to have an operation, including minor surgery and dental work, inform your doctor or dentist that you are taking this medicine.
Why is it important to keep my appointments with the doctor?
Keep your appointments with your doctor. Your doctor needs to monitor your condition and check your response to the medication regularly.
- Routine tests (e.g. kidney function, electrolyte levels) may be done while you are being treated with this medicine. Your doctor will advise you about how often you need to have these tests.
- Your blood pressure may fall to unsafe levels without you noticing it. Monitor your blood pressure regularly during treatment.
- Regular monitoring of fluid status may also be needed.
What lifestyle changes can I make to improve my blood pressure?
Regular exercise and eating a healthy diet will help control your blood pressure and improve your overall health. Engage in physical activity like walking for at least 30 to 60 minutes on most days of the week. If you have not exercised for a long time, start with light exercises such as slow walks. Speak to your doctor about what type of exercise would be suitable for you. Follow a healthy diet plan by eating more fruits, vegetables, whole grains, and low-fat dairy products and reduce your intake of foods high in saturated fat, cholesterol, and sodium. Cutting down on deep-fried foods and using less salt when cooking can kick-start your healthy diet.
If you smoke, you should try to quit. Smoking is harmful to your blood pressure, heart, and overall health. Speak to your doctor or pharmacist about ways to stop your smoking habit.
Chlorothiazide may cause any of the following side effects: headache, dizziness, nausea, vomiting, diarrhoea, constipation, stomach discomfort, weakness, and restlessness.
This medicine may cause your blood pressure to fall suddenly when you get up from a sitting or lying down position and you may feel giddy. To minimise this problem, stand up slowly.
You may need to pass urine more often while you are being treated with Chlorothiazide. As your body adjusts to the medicine, this urination effect should also decrease.
This medicine may also make your skin more sensitive to sunlight. Apply sunscreen when going outdoors and avoid prolonged exposure to sunlight and UV lamps.
Some side effects may need immediate medical help. Alert your doctor quickly if you experience any of the following:
- rashes, breathlessness, swelling of the face, eyes, or mouth
- fast or irregular heartbeat, severe dizziness or passing out, mood changes, confusion, increased thirst, muscle pain or weakness, fits or seizures
- rashes with peeling of the skin or blistering of the lips, mouth, or eyes accompanied by fever
- flushing, fast breathing, unusual hunger or thirst, breath that smells like fruit, sleepiness
Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.
Inform your doctor and pharmacist if you are taking any of these medicines:
- medicines for diabetes e.g. insulin
- other medicines for high blood pressure
- medicines for epilepsy (fits or seizures)
- strong painkillers
- corticosteroids (anti-inflammatory medicines)
- NSAIDs (medicines for pain and inflammation) e.g. ibuprofen, naproxen
- cholesterol-lowering medicines e.g. colestyramine, colestipol
- lithium (medicine for mood disorders)
This list does not include all medicines that may interact with Chlorothiazide.
Always notify your doctor and pharmacist if you are taking any other medicines, including herbal tonics such as traditional Chinese medicines, supplements, and medicines that you buy without a prescription.
Avoid alcohol. Alcohol intake may increase the risk of fall in blood pressure caused by Chlorothiazide.
Store in a cool, dry place away from the reach of children.
Protect from freezing.
Medicines must not be used past the expiry date.
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