Medically reviewed by Jessica Swirble, PharmD
Last updated on April 18, 2025
Drug Information | Side Effects | Use & Dosage | Request an Online Prescription
Hydrochlorothiazide is a prescription medication used to treat high blood pressure and edema (fluid retention in body tissue).
Hydrochlorothiazide is a diuretic, a class of drugs also known as “water pills.” Its name is commonly abbreviated to “HCTZ.”
Hydrochlorothiazide is prescribed to treat high blood pressure. It is also used to treat edema (fluid retention) caused by medical conditions such as:
Hydrochlorothiazide is also prescribed to patients who are experiencing edema from using medications that contain corticosteroids or estrogen.
Hydrochlorothiazide is classified as a diuretic or “water pill.” These medications work by helping the kidneys pull excess sodium and fluid from blood cells into the urine. The body then releases this extra salt and water through the urine stream.
Excess sodium causes the body to retain more fluid. The more fluid held in the blood cells, the greater the pressure on the blood vessels. This makes it harder for the heart to pump blood throughout the body, raising blood pressure.
Hydrochlorothiazide promotes sodium excretion through urine. This lowers fluid levels in the body, a key part of treating edema. Getting rid of excess fluid also lowers blood pressure, as the heart doesn’t have to work as hard to pump blood through blood vessels.
Hydrochlorothiazide is available as an oral tablet or oral capsule.
The dosage and frequency of use depend on the condition being treated, its severity, and how you respond to the medication.
Follow your healthcare provider's instructions regarding dosage and schedule. Do not exceed the prescribed dose or frequency of use without consulting your provider.
Hydrochlorothiazide is used to manage high blood pressure and edema. The effects can be noticeable within a few days, but it may take several weeks to achieve optimal control of blood pressure.
Continue using hydrochlorothiazide as prescribed, even if you start feeling better. Regular use according to your prescription is crucial for the management of symptoms.
While hydrochlorothiazide is primarily used for treating high blood pressure and edema, healthcare providers may prescribe it off-label for other conditions.
Discuss any alternative uses of hydrochlorothiazide with your healthcare provider.
Hydrochlorothiazide is available in the following dosage forms:
Hydrochlorothiazide is a prescription medication. You must have a valid prescription from a licensed healthcare provider to obtain it.
The use of hydrochlorothiazide can lead to various side effects in some individuals.
Common mild side effects of hydrochlorothiazide use include:
More severe side effects of hydrochlorothiazide use can include:
If you experience any severe or concerning side effects while taking hydrochlorothiazide, contact your healthcare provider right away.
Inform your healthcare provider about any existing medical conditions, allergies, or other medications you are taking before starting treatment with hydrochlorothiazide. This includes prescription drugs, over-the-counter medications, and dietary supplements, as they may interact with hydrochlorothiazide.
Tell your provider if you are taking these medications or supplements:
You should also mention medical conditions such as:
If you are pregnant, planning to become pregnant, or breastfeeding, discuss the potential risks and benefits of using hydrochlorothiazide with your healthcare provider.
Take hydrochlorothiazide exactly as prescribed by your healthcare provider. Do not exceed the recommended dose or duration of treatment.
Hydrochlorothiazide can cause dizziness. Because of this, you should not operate a motor vehicle or heavy machinery until you know how this medication affects you.
It's important to complete the full course of treatment, even if you feel better, to ensure the medication's effectiveness in managing your condition.
In case of a hydrochlorothiazide overdose, seek medical attention immediately. Symptoms of overdose may include severe dizziness, fainting, confusion, or unusual tiredness. If you suspect an overdose, contact the poison control helpline at 1-800-222-1222 or call emergency services.
Hydrochlorothiazide is available in the following forms:
The typical starting dose of hydrochlorothiazide varies depending on the condition being treated, the severity of symptoms, and individual patient factors. It is crucial to follow your healthcare provider's instructions regarding dosage and administration.
For high blood pressure:
For edema:
The dosage may be adjusted based on the response and tolerance to the medication. Your healthcare provider will determine the most appropriate dose based on your medical history and your response to the medication.
Hydrochlorothiazide should be taken as prescribed by your healthcare provider. Do not exceed the recommended dose or duration of treatment without consulting your provider.
If you have any questions about your dosage or need adjustments, contact your healthcare provider for guidance. If you want to talk to a provider right away, consider scheduling an online doctor appointment through a telehealth platform like Sesame.
If you miss a dose of hydrochlorothiazide, take it as soon as you remember unless it is close to the time for your next scheduled dose. In that case, skip the missed dose and continue your regular dosing schedule. Do not double the dose to make up for a missed one.
Take hydrochlorothiazide around the same time every day to maintain a consistent amount of medication in your body.
Continue taking hydrochlorothiazide as prescribed by your healthcare provider, even if you start feeling better. It's important to keep taking the medication as directed to manage your condition effectively.
Do not suddenly stop taking hydrochlorothiazide; this can cause your blood pressure to go back up or your edema to worsen.
If you have any concerns or questions about your medication, discuss them with your healthcare provider for medical advice and recommendations.
Store hydrochlorothiazide according to the instructions provided by your healthcare provider or pharmacist. Keep it at room temperature, away from light and moisture. Ensure the container is tightly closed and out of reach of children.
Do not use expired medication or medications that appear damaged or discolored. If you have any questions about storage, consult your healthcare provider or pharmacist for guidance.