Hydrochlorothiazide is used on its own or together with other antihypertensive medicines to keep your blood pressure under control.
It is also used to treat water retention caused by heart failure, liver or kidney 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".
Hydrochlorothiazide may also be used to treat other medical conditions, as decided by your doctor.
Take this medicine 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.
Take Hydrochlorothiazide with food. Try to take it at the same time each day.
You may need to pass urine more often while being treated with this medicine. Take it early in the day, preferably in the morning, to avoid waking up frequently at night to go to the toilet.
Hydrochlorothiazide must be taken regularly for it to work well. Continue taking this medicine even when you feel better. Do not stop taking it unless instructed by your 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 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 Hydrochlorothiazide if you ever had an allergic reaction (e.g. rashes, breathlessness, swollen eyes) to this medicine or similar medicines such as sulfonamide-containing medicines.
Alert your doctor if you have the following conditions:
- are unable to pass urine
- severe kidney disease
as Hydrochlorothiazide may not be suitable for you.
Inform your doctor if you have the following conditions:
- diabetes
- gout (abnormal metabolism of uric acid)
- high cholesterol
- liver disease
- parathyroid gland disease (high level of parathyroid hormone due to overactivity of parathyroid glands)
- mild to moderate kidney disease
- systemic lupus erythematosus (SLE) - autoimmune disease that causes inflammation
- have Addison's disease (a disorder of the adrenal glands)
Let your doctor know if you are pregnant or breastfeeding.
If you are going to have an operation, including minor surgery and dental work, inform your doctor or dentist that you are taking Hydrochlorothiazide.
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. liver and kidney function, electrolyte, cholesterol and sugar levels,) may be done while you are being treated with this medicine.
- Your blood pressure may fall to unsafe levels without you noticing it. Monitor your blood pressure during treatment.
- Regular monitoring of skin reactions such as appearance of moles or lesions may also be needed.
Your doctor will advise you about how often you will need to have these tests.
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.
Hydrochlorothiazide may cause dizziness or temporary blurred vision. If affected, do not drive or take part in any activity in which you need to be alert.
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 Hydrochlorothiazide. As your body adjusts to the medicine, this urination effect should also decrease.
Hydrochlorothiazide may also cause any of the following side effects: nausea, constipation, lack of appetite, vomiting, diarrhoea, tiredness, weakness, stomach cramps, headache.
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, tightness in the chest or throat
- dry mouth, muscle pain or cramps, abnormally fast heart beat
- dark urine or yellow skin or eyes
- any unexplained bruising or bleeding
Hydrochlorothiazide may also make your skin more sensitive to sunlight. Apply sunscreen when going outdoors and avoid prolonged exposure to sunlight and UV lamps.
This medicine may cause the level of your red blood cells and platelets to drop.
Red blood cells carry oxygen around your body. A fall in the level of red blood cells may make you feel tired and worn out.
Platelets help your blood to clot when there is a cut in the skin. A fall in the level of your platelets may put you at risk of bleeding more than usual. Do not take part in activities where you may fall or get injured, such as contact sports. Inform your doctor if you get any unusual bruising (large bruises or several bruises, especially if the bruises appeared on their own) or bleeding that takes a long time to stop (for example, too much bleeding when you floss or brush your teeth).
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:
- lithium (medicine for mood disorders)
- medicines for heart disease or high blood pressure e.g. digoxin, quinidine, enalapril
- NSAIDs (medicines for pain and inflammation) e.g. indometacin
- strong painkillers e.g. fentanyl, oxycodone
- antibiotic e.g. amphotericin B
- medicine for diabetes e.g. glipizide
- medicine to treat hyperactivity disorders e.g. amphetamine
- corticosteroids (medicines for inflammation) e.g. prednisolone
- cholesterol-lowering medicines e.g. cholestyramine, colestipol
This list does not include all medicines that may interact with Hydrochlorothiazide.
Always notify your doctor and pharmacist if you are taking any other medicines, including herbal tonics such as traditional Chinese medicine, supplements and medicines that you buy without a prescription.
Your doctor may give you potassium supplements while you are being treated with Hydrochlorothiazide. Alternatively, he may tell you to eat more of foods that are high in potassium, such as orange juice, bananas or prunes.
Avoid alcohol.
Store in a cool, dry place away from the reach of children.
Medicines must not be used past the expiry date.
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