Hydrochlorothiazide
A thiazide diuretic used to treat high blood pressure and fluid retention.
What is Hydrochlorothiazide?
Hydrochlorothiazide is a thiazide diuretic commonly prescribed for hypertension and edema.
It helps lower blood pressure by removing excess salt and water from the body.
History & Background
Hydrochlorothiazide has been used for decades and remains one of the most commonly prescribed antihypertensive medications worldwide.
Chemical Structure & Properties
- IUPAC name: 6-chloro-3,4-dihydro-2H-1,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide
- Molecular formula: C₇H₈ClN₃O₄S₂
- Molar mass: 297.73 g/mol
- Functional groups: Sulfonamide, thiazide ring
Mechanism of Action
Hydrochlorothiazide lowers blood pressure by:
- Inhibiting sodium-chloride reabsorption in distal tubules
- Increasing excretion of sodium and water
- Reducing plasma volume
Pharmacokinetics
- Absorption: Moderate oral absorption
- Peak plasma time: 1–5 hours
- Half-life: 6–15 hours
- Metabolism: Not metabolized
- Excretion: Urine (unchanged)
Medical Uses
- Hypertension
- Edema (heart failure, liver, kidney disease)
- Prevention of kidney stones
- Nephrogenic diabetes insipidus
Dosage Guidelines
Hypertension: 12.5–25 mg once daily
Edema: 25–100 mg daily
⚠️ Take in the morning to avoid nighttime urination.
Side Effects
- Hypokalemia
- Dehydration
- Dizziness
- Increased urination
Warnings & Precautions
- Monitor electrolytes regularly
- Use caution in diabetes and gout
- Avoid severe dehydration
Drug Interactions
- Digoxin (↑ toxicity with low potassium)
- Lithium
- NSAIDs
Frequently Asked Questions
Is hydrochlorothiazide a diuretic? – Yes.
Does it lower BP? – Yes.
Does it cause frequent urination? – Yes.
Is it safe long-term? – Yes, with monitoring.
⚠️ Educational content only. Not a substitute for professional medical advice.