Hydrochlorothiazide
- Class: Thiazide diuretic
- Used for: high blood pressure
- Say it: hye-droh-klor-oh-THYE-uh-zide
- Forms: tablet, capsule
Remember the name – HYDRO → water
HYDROchlorothiazide = the HYDRO-thief. It siphons salt and water out of the body until the pressure comes down.
Careful which way the water goes: HYDRO names the thing it removes, not the thing it adds. Blocking the distal tubule's sodium transporter means salt — and the water following it — leaves in the urine.
HYDROchlorothiazide = the HYDRO-thief. It siphons salt and water out of the body until the pressure comes down.
Careful which way the water goes: HYDRO names the thing it removes, not the thing it adds. Blocking the distal tubule's sodium transporter means salt — and the water following it — leaves in the urine.
Mnemonic: ThiaZIDES hold on to calcium
Thiazides act in the distal tubule and keep calcium in the body — loop diuretics lose it. Both lose potassium. Holding calcium back is why thiazides suit someone with calcium kidney stones.
Thiazides act in the distal tubule and keep calcium in the body — loop diuretics lose it. Both lose potassium. Holding calcium back is why thiazides suit someone with calcium kidney stones.
Side effects
Common: low potassium, frequent urination, gout flare
Serious: low sodium
Typical dose
12.5–25 mg once daily
Above 25 mg adds little blood-pressure benefit but steadily more hyponatraemia and hypokalaemia.
Check yourself
Where in the kidney does Hydrochlorothiazide act?
- The distal convoluted tubule
- The loop of Henle
- The aldosterone receptor in the collecting duct
- The glomerulus
Show answer
A. The distal convoluted tubule
Thiazides work on the distal tubule, further down than the loop. Less salt is handled there, which is exactly why a thiazide is a milder diuretic than furosemide.
See it, don't memorize it
The app has the mechanism comic and a patient case for Hydrochlorothiazide – plus the name link, the class mnemonic, pronunciation you can hear, and a self-check, for the top 100 drugs. One purchase, no subscription, no account.