Generic Hydrochlorothiazide

Common use
Hydrochlorothiazide is a thiazide diuretic used to treat high blood pressure and fluid retention (edema) caused by various medical conditions, including heart failure, liver disease, and kidney disorders. It helps the body eliminate excess salt and water through urine. Lowering blood pressure reduces the risk of stroke, heart attack, and kidney problems. It is often used alone or in combination with other antihypertensive drugs.

Dosage and direction
The medication is usually taken once daily in the morning, with or without food. Dosage varies depending on the condition being treated and individual response, typically starting at 12.5–25 mg per day. Take the tablet with a full glass of water. Avoid taking it late in the day to prevent nighttime urination.

Precautions
Before taking hydrochlorothiazide, inform your doctor if you have kidney or liver problems, gout, diabetes, or electrolyte imbalances. Use caution in hot weather or during exercise, as the drug can cause dehydration. Routine blood tests may be needed to monitor potassium, sodium, and kidney function. This medication may increase sensitivity to sunlight — use sunscreen and wear protective clothing.

Contraindications
Hydrochlorothiazide is contraindicated in individuals with anuria (inability to produce urine), severe kidney impairment, or known hypersensitivity to sulfonamide-derived drugs. It should not be used during pregnancy unless clearly needed. Caution is advised in patients with diabetes or a history of gout. Do not use in combination with drugs that significantly reduce potassium without close monitoring.

Possible side effect
Common side effects include increased urination, dizziness, headache, and muscle cramps. It may also cause low potassium, low sodium, high blood sugar, or elevated uric acid levels. Rare but serious reactions include severe dehydration, pancreatitis, or allergic responses. Seek medical attention if you experience irregular heartbeat, severe fatigue, or difficulty breathing.

Drug interaction
Hydrochlorothiazide may interact with other blood pressure medications, NSAIDs, lithium, corticosteroids, and diabetic drugs. Combining it with alcohol or barbiturates may enhance dizziness or fainting. Use with digoxin requires caution due to electrolyte imbalances. Always inform your doctor about all medications and supplements you are taking.

Missed dose
If you miss a dose, take it as soon as you remember unless it's close to your next scheduled dose. In that case, skip the missed dose — do not double it. Try to take the medication at the same time each day. Missing doses may reduce blood pressure control or worsen edema.

Overdose
An overdose can lead to excessive fluid or electrolyte loss, causing symptoms like extreme thirst, confusion, fainting, or muscle weakness. Seek emergency medical help immediately. Treatment usually involves fluid and electrolyte replacement. Hospital observation may be required in severe cases.

Storage
Store hydrochlorothiazide at room temperature, away from light, moisture, and heat. Keep the tablets in a tightly closed container. Do not use after the expiration date. Keep out of reach of children and pets.

Disclaimer

We provide only general information about medications which does not cover all directions, possible drug integrations, or precautions. Information at the site cannot be used for self-treatment and self-diagnosis. Any specific instructions for a particular patient should be agreed with your health care adviser or doctor in charge of the case. We disclaim reliability of this information and mistakes it could contain. We are not responsible for any direct, indirect, special or other indirect damage as a result of any use of the information on this site and also for consequences of self-treatment.

Clinical Verification

Last Clinically Updated: August 15, 2026

Written By

Dr. Elena Vance, PharmD

Clinical Specialist in Neuropharmacology

Fact Checked By

Marcus Thorne, MS

Biomedical Data & FDA Label Verification

Medically Reviewed By

Dr. Arthur Campbell, MD

Board-Certified Psychiatrist (ABPN)