Hydrochlorothiazide

Blood pressure

Also known as Microzide, HCTZ

Hydrochlorothiazide — most people just say HCTZ — is a mild diuretic, or water pill. It nudges your kidneys to pass a little more salt and water out in your urine. Less fluid in your bloodstream means lower pressure on your artery walls. It's one of the oldest and most trusted blood pressure medicines around.

How to take it

When

In the morning. Taking it late in the day means midnight bathroom trips.

Food

With or without food.

Avoid

Getting dehydrated — go easy in hot weather and during illness. It can also make your skin burn faster in the sun, so cover up or use sunscreen.

Good to know

It can lower your potassium over time. Your doctor may check this with an occasional blood test.

Missed a dose?

Take it when you remember that morning or early afternoon. If it's evening already, skip it — a missed dose is better than a sleepless night. Never double up.

Common side effects

Urinating more often, especially the first weeks
Mild dizziness or lightheadedness
Leg cramps — can signal low potassium, worth mentioning to your doctor
It can nudge up blood sugar and trigger gout in people prone to it

Call a doctor if

Severe dizziness or fainting
An irregular or pounding heartbeat
Muscle weakness or cramps that don't ease — possible low potassium
Sudden eye pain or vision changes — rare but urgent

Educational only. This summary is drawn from public FDA labeling and MedlinePlus and simplified for readability. Your prescription label and your pharmacist always come first — doses and instructions vary from person to person.