Hydrochlorothiazide Hydrochlorothiazide is an oral medication, either tablet or capsule, prescribed to treat hypertension. The medication is a diuretic—also called a water pill—that lowers blood pressure by increasing urination and removing excess water and electrolytes. Hydrochlorothiazide may also help reduce swelling. Read more about hypertension.
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How to use this information
This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective or appropriate for you. This information is not individual medical advice and does not substitute for the advice of a medical provider. If you have any questions, go to your patient dashboard and request a callback for complete information about this product and your specific health needs.
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What you should know about Hydrochlorothiazide
  • This medication is used to treat high blood pressure. Lowering high blood pressure helps prevent strokes, heart attacks and kidney problems.
  • Hydrochlorothiazide belongs to a class of drugs known as diuretics/"water pills." It works by causing you to make more urine, helping your body get rid of extra salt and water.
  • This medication also reduces extra fluid in the body (edema) caused by conditions such as heart failure, liver disease or kidney disease. This can lessen symptoms like shortness of breath or swelling in your ankles or feet.
How to take Hydrochlorothiazide
  • Take this medication by mouth as directed by your medical provider, usually once daily in the morning with or without food.
  • If you take this drug too close to bedtime, you may need to wake up to urinate. It is best to take this medication at least 4 hours before your bedtime.
  • The dosage is based on your medical condition and response to treatment.
  • Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time each day. Keep taking this medication even if you feel well. Most people with high blood pressure do not feel sick.
  • If you also take certain drugs to lower your cholesterol—for example, bile acid-binding resins such as Cholestyramine or Colestipol—take Hydrochlorothiazide at least 4 hours before or at least 4 to 6 hours after these medications.
  • Tell your medical provider if your condition does not get better or if it gets worse—for example, your blood pressure readings remain high or increase.
Potential side effects
  • Upset stomach, dizziness or headache may occur as your body adjusts to the medication. If any of these effects continue or get worse, tell your medical provider or pharmacist right away.
  • To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.
  • Anemia or low platelets. Get medical help right away if you have bleeding, bruising, or pale skin.
  • Remember that this medication has been prescribed because your medical provider has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not experience serious side effects.
  • Tell your medical provider right away if you have any serious side effects, including decrease in vision or eye pain.
  • In rare cases, this product may cause serious and possibly fatal liver problems. Get medical help right away if you have any symptoms of liver damage, such as:

    • Nausea or vomiting that doesn't stop
    • Loss of appetite
    • Stomach or abdominal pain
    • Yellowing eyes or skin
    • Dark urine
  • This medication may cause dehydration, electrolyte imbalance and kidney injury. Tell your medical provider right away if you have any symptoms of dehydration or electrolyte imbalance, including:

    • Extreme thirst
    • Very dry mouth
    • Muscle cramps or weakness
    • Slow, fast or irregular heartbeat
    • Confusion
    • Decreased urination
  • This medication may cause:

    • Lupus
    • Fluid accumulation in the lungs. Get medical help right away if you have any symptoms of chest pain, trouble breathing, feeling like you will pass out, leg swelling.
  • A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

    • Rash
    • Itching or swelling, especially of the face/tongue/throat
    • Severe dizziness
    • Trouble breathing
  • This is not a complete list of possible side effects. If you notice other effects not listed above, request a callback for medical advice. You may also report side effects to the FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

Precautions to be aware of
  • Before taking Hydrochlorothiazide, tell your medical provider or pharmacist if you are allergic to it, or if you have any other allergies. This product may contain inactive ingredients—such as sulfites found in some brands—which can cause allergic reactions or other problems. Go to your patient dashboard and request a medical provider callback for more details.
  • Before using this medication, tell your medical provider or pharmacist your medical history, especially of:

    • Adrenal insufficiency (Addison's disease)
    • An allergy to sulfonamides ("sulfa") because there may be cross-reactivity between the two classes of drugs
    • Diabetes
    • Glaucoma or other vision issues
    • Gout
    • High cholesterol/triglycerides
    • Kidney disease
    • Liver disease
    • Lupus
    • Parathyroid disease or history of high calcium levels
    • Skin cancer
  • This drug may make you dizzy, which can be exacerbated by alcohol or marijuana (cannabis). Do not drive, use machinery or do anything that requires alertness until you can do it safely. Limit alcoholic beverages. Talk to your medical provider if you are using marijuana.
  • Severe sweating, diarrhea or vomiting can increase the risk of dehydration. Report prolonged diarrhea or vomiting to your medical provider. To prevent dehydration, drink plenty of fluids unless your medical provider directs you otherwise.
  • If you have diabetes, Hydrochlorothiazide may affect your blood sugar. Check your blood sugar regularly as directed by your medical provider. Your medical provider may need to adjust your diabetes medication, exercise program or diet.
  • This drug may decrease your potassium levels. Ask your medical provider about foods high in potassium (like bananas and orange juice) or about using a salt substitute containing potassium. A potassium supplement may be prescribed by your medical provider.
  • This medication may make you more sensitive to the sun. It may also increase your risk for skin cancer, especially if you take it for a long time. Limit your time in the sun. Avoid tanning booths and sunlamps. Use sunscreen and wear protective clothing when outdoors. Tell your medical provider right away if you get sunburned, have skin blisters/redness or notice new or changed moles/skin lesions.
  • Before having surgery, tell your doctor or dentist about all the products you use, including prescription drugs, nonprescription drugs and herbal products.
  • Older adults may be more sensitive to the effects of this drug, especially dizziness.
  • During pregnancy, this medication should be used only when there is a clear need. Discuss the risks and benefits with your OB/GYN.
  • This drug passes into breast milk, but is unlikely to harm a nursing infant. Consult your OB/GYN before breastfeeding.
Drug interactions (See also “How to take Hydrochlorothiazide” section)
  • Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions.
  • Keep a list of all the products you use—including prescription/nonprescription drugs and herbal products—and share it with your medical provider and pharmacist.
  • Do not start, stop or change the dosage of any medicines without your medical provider's approval.
  • Some products that may interact with this drug include:

    • Allopurinol
    • Certain diabetes medications
    • Certain antidepressants or antipsychotic medications
    • Certain heart medications
    • Dofetilide
    • Licorice
    • Lithium
    • Multivitamins and vitamin D supplements
    • Steroids
  • Some products have ingredients that could raise your blood pressure or worsen your swelling. Tell your pharmacist what products you are using, and ask how to use them safely—especially cough-and-cold products, diet aids or NSAIDs such as Ibuprofen and Naproxen.
  • This medication may interfere with certain lab tests like parathyroid function, possibly causing false test results. Make sure lab personnel and all your medical providers know you use this drug.
What to do in the event of an overdose

Symptoms of overdose may include severe dizziness, weakness or fainting.

If someone has overdosed and has serious symptoms—such as passing out or trouble breathing—call 911. If symptoms from taking this medication are less severe, call your local poison control center at 1-800-222-1222 right away.

Additional notes
  • Do not share this medication with others.
  • Lifestyle changes that may help this medication work better include exercising, stopping smoking and eating a low-cholesterol/low-fat diet. Consult your medical provider for more details.
  • Lab and/or medical tests—such as potassium levels, kidney function and skin exams—should be done while you are taking this medication. Keep all medical and lab appointments. Consult your medical provider for more details.
  • Check your blood pressure and pulse (heart rate) regularly while taking this medication. Learn how to check your own blood pressure and pulse at home, and share the results with your medical provider.
What to do if you miss a dose

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

How to store this medication
  • Store at room temperature away from light and moisture. Do not store in the bathroom.
  • Keep all medications away from children and pets.
  • Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details.
Treatment for
Generic Name
Drug Class
Diuretic (water pill)

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