How Do Thiazide Diuretics Work?

Diuretics also known as water pills are a class of drugs that cause diuresis (increased production of urine by the kidneys). Diuretics are drugs that work on the kidneys to remove electrolytes such as sodium and chloride from the body in the urine. These electrolytes draw water along with them; thus, excess water also gets eliminated in the urine. They are used to treat conditions associated with the presence of excess sodium and water in the body such as hypertension and fluid overload in the body that may damage major organs such as the heart and cause edema (accumulation of fluid in the body tissues causing swelling, usually seen due to damage to the small vessels).

Thiazide diuretics are drugs that cause both natriuresis (removal of sodium in the urine) and diuresis. Thiazide diuretics work by blocking sodium and chloride (Na/Cl) channels in the distal convoluted tubule of the nephron and inhibit the reabsorption of sodium and water. This also causes a loss of potassium and calcium ions.

Thiazide diuretics are taken orally and used in conditions such as:

• Primary hypertension (increase in blood pressure without any underlying cause)
• Edema (swelling caused by the accumulation of fluid in the body) associated with:
  • Severe heart failure
  • Liver cirrhosis (severe liver damage that causes scarring and liver failure)
  • Corticosteroid therapy
  • Estrogen therapy
• Salt and fluid retention associated with congestive heart failure
• Renal stones
• Diabetes insipidus (abnormally large amount of urine is produced which causes an abnormality of fluid balance in the body)
• Osteoporosis (bones become weak and brittle due to decreased bone density)

The side effects associated with thiazide diuretics include:

• Hypokalemia (decrease in potassium levels in the blood)
• Hyponatremia (decrease in sodium levels in the blood)
• Metabolic alkalosis (increase in body’s pH with an increase in bicarbonates)
• Hypercalcemia (increase in calcium levels in the blood)
• Hyperglycemia (increase in sugar levels in the blood)
• Hyperuricemia (increase in potassium levels in the blood)
• Hyperlipidemia (increased fats in the blood)
• Sexual dysfunction
• Dizziness
• Blurred vision
• Loss of appetite
• Stomach discomfort
• Sulfonamide allergy
  • Rash
  • Hives (itchy, raised bumps on the skin caused by food or medicine)
  • Swelling of tongue, throat, and lips
  • Trouble breathing
  • Asthma
  • Headache
  • Anaphylaxis (life-threatening severe allergy)

Rare but serious side effects of thiazide diuretics may include:

• Pancreatic toxicity (abnormality in the function of the pancreas caused by the toxic nature of the drug)
  • Acute pancreatitis (inflammation of the pancreas)
  • Increase pancreatic secretions
  • Pancreatic ischemia (damage to pancreatic tissue due to lack of oxygen and nutrients caused by damage to blood vessels)

The information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of thiazide diuretics drugs include:

• Chlorothiazide (Diuril)
• Chlorthalidone (Chlorthalid, Hygroton, Thalitone)
• Hydrochlorothiazide (Oretic, Microzide, HydroDiuril, Hydro, HCTZ, Esidrix)
• Methyclothiazide