If you are dealing with fluid retention or high blood pressure, your doctor may prescribe diuretics, commonly known as water tablets. These medications are essential for managing conditions like heart failure, kidney disease, and hypertension.
In this guide, we break down the 10 most common diuretics, how they work, and what you should know about their side effects.
Diuretics help your body eliminate excess water and salt (sodium). By stimulating the kidneys to release more sodium into your urine, these medications reduce the total volume of fluid flowing through your veins and arteries. This process effectively:
Lowers blood pressure
Reduces swelling (edema)
Eases the workload on the heart
Common Conditions Treated with Diuretics
Doctors typically prescribe water tablets for:
Congestive Heart Failure (CHF)
Chronic Kidney Disease (CKD)
Liver Cirrhosis/Failure
Nephrotic Syndrome
Glaucoma
Diuretics are categorized into different “classes” based on which part of the kidney they affect. Here are the 10 most frequently used:
Perhaps the most well-known water tablet, Furosemide is a powerful “Loop” diuretic used for rapid fluid removal in heart or kidney failure.
Typical Dosage: 40mg once daily to 120mg twice daily.
Often a first-line treatment for hypertension (high blood pressure) in the UK and Europe.
Typical Dosage: 2.5mg to 10mg once daily.
Unlike other diuretics, Spironolactone helps the body hold onto potassium while losing water. It is frequently used for heart failure and liver-related fluid buildup (ascites).
Typical Dosage: 25mg to 100mg once daily.
Similar to Furosemide but more potent per milligram. It is often used when Furosemide isn’t effective enough.
Typical Dosage: 1mg once daily to 2mg twice daily.
A common choice for managing long-term high blood pressure with a lower risk of certain metabolic side effects.
A very potent tablet often used in combination with loop diuretics to “supercharge” fluid removal in cases of severe resistance.
Usually prescribed alongside other diuretics to prevent potassium levels from dropping too low.
Primarily used to reduce fluid pressure in the eyes (glaucoma) or to prevent altitude sickness.
A long-acting loop diuretic used for edema associated with congestive heart failure.
Unlike the others, this is typically administered via IV in hospital settings to reduce brain swelling (intracranial pressure) after a head injury.
Not all water tablets are created equal. Depending on your condition, a doctor will choose a specific strength:
| Rank | Class | Example | Use Case |
| 1 | Osmotic | Mannitol | Emergency/Hospital use only |
| 2 | Loop | Furosemide | Severe fluid overload/Heart failure |
| 3 | Thiazide | Metolazone | High blood pressure/Combination therapy |
| 4 | Potassium-Sparing | Spironolactone | Heart failure/Hormonal balance |
| 5 | Carbonic Anhydrase | Acetazolamide | Glaucoma/Altitude sickness |
While generally safe, diuretics can significantly alter your body’s chemistry.
Important: Diuretics can cause your potassium levels to fluctuate. Loop and Thiazide diuretics may cause hypokalaemia (low potassium), while Potassium-sparing diuretics can cause hyperkalaemia (high potassium). Both can affect your heart rhythm.
Other common side effects include:
Dehydration: Leading to dizziness or low blood pressure.
Electrolyte Imbalance: Low sodium or magnesium.
Muscle Cramps: Often due to mineral loss.
Gout: High levels of uric acid can trigger joint pain.
Understanding the different types of water tablets helps you manage your health more effectively. Whether you are taking Furosemide for heart health or Indapamide for blood pressure, always monitor for symptoms of dehydration and ensure you attend regular blood tests to check your kidney function and salt levels.
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