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. This helps 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 such as shortness of breath or swelling in your ankles or feet.
Take this medication by mouth as directed by your doctor, 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 (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 doctor if your condition does not get better or if it gets worse (for example, your blood pressure readings remain high or increase).
Upset stomach, dizziness, or headache may occur as your body adjusts to the medication. If any of these effects last or get worse, tell your doctor or pharmacist promptly. To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor right away if you have any serious side effects, including: decrease in vision, eye pain. This medication may cause a loss of too much body water (dehydration) and salt/minerals. Tell your doctor right away if you have any symptoms of dehydration or mineral loss, including: extreme thirst, very dry mouth, muscle cramps/weakness, slow/fast/irregular heartbeat, confusion, decreased urination. 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/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, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
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.
See also How To Use 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 doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval. Some products that may interact with this drug include: dofetilide, lithium. 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/naproxen). This medication may interfere with certain lab tests (such as parathyroid function), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.
If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: severe dizziness, weakness, fainting.