What is hydrochlorothiazide?

• Hydrochlorothiazide is a thiazide diuretic (water pill) that helps prevent your body from absorbing too much salt, which can cause fluid retention.
• Hydrochlorothiazide is used to treat high blood pressure (hypertension).
• Hydrochlorothiazide is also used to treat fluid retention (edema) in people with congestive heart failure, cirrhosis of the liver, or kidney disorders, or edema caused by taking steroids or estrogen.

Important information

• You should not use hydrochlorothiazide if you are unable to urinate.
• Before using hydrochlorothiazide, tell your doctor if you have liver disease, kidney disease, glaucoma, asthma or allergies, gout, diabetes, or if you are allergic to sulfa drugs or penicillin.
• Avoid drinking alcohol, which can increase some of the side effects of this medicine.
• Avoid becoming overheated or dehydrated during exercise and in hot weather. Follow your doctor's instructions about the type and amount of liquids you should drink. In some cases, drinking too much liquid can be as unsafe as not drinking enough.
• There are many other drugs that can interact with hydrochlorothiazide. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor. Keep a list of all your medicines and show it to any healthcare provider who treats you.
• If you are being treated for high blood pressure, keep using hydrochlorothiazide even if you feel fine. High blood pressure often has no symptoms.

Before taking this medicine

You should not use hydrochlorothiazide if you are allergic to it, or if you are unable to urinate.

To make sure hydrochlorothiazide is safe for you, tell your doctor if you have:

• kidney disease;
• liver disease;
• gout;
• glaucoma;
• low levels of potassium or sodium in your blood;
• high levels of calcium in your blood;
• a parathyroid gland disorder;
• diabetes; or
• an allergy to sulfa drugs or penicillin.

Hydrochlorothiazide is not expected to be harmful to an unborn baby. However, if you take this medicine during pregnancy, your newborn baby may develop jaundice or other problems. Tell your doctor if you are pregnant or plan to become pregnant while taking hydrochlorothiazide.

Hydrochlorothiazide can pass into breast milk and may harm a nursing baby. You should not breast-feed while using this medicine.

This medicine is not approved for use by anyone younger than 18 years old.

How should I take hydrochlorothiazide?

Take hydrochlorothiazide exactly as prescribed by your doctor. Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not use this medicine in larger or smaller amounts or for longer than recommended.

• Hydrochlorothiazide is usually taken once per day. Follow your doctor's dosing instructions very carefully.
• Call your doctor if you have ongoing vomiting or diarrhea, or if you are sweating more than usual. You can easily become dehydrated while taking this medicine, which can lead to severely low blood pressure or a serious electrolyte imbalance.
• While using hydrochlorothiazide, you may need frequent medical tests and blood pressure checks. Your blood and urine may both be tested if you have been vomiting or are dehydrated.
• If you need surgery, tell the surgeon ahead of time that you are using hydrochlorothiazide. You may need to stop using the medicine for a short time.
• Keep using this medicine as directed, even if you feel well. High blood pressure often has no symptoms. You may need to use blood pressure medicine for the rest of your life.
• Store hydrochlorothiazide at room temperature away from moisture, heat, and freezing. Keep the bottle tightly closed when not in use.

What happens if I miss a dose?

• Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

• Seek emergency medical attention.
• Overdose symptoms may include nausea, weakness, dizziness, dry mouth, thirst, and muscle pain or weakness.

What should I avoid while taking hydrochlorothiazide?

• Drinking alcohol with this medicine can cause side effects.

Avoid becoming overheated or dehydrated during exercise, in hot weather, or by not drinking enough fluids. Follow your doctor's instructions about the type and amount of liquids you should drink. In some cases, drinking too much liquid can be as unsafe as not drinking enough.

Hydrochlorothiazide side effects

Get emergency medical help if you have signs of an allergic reaction to hydrochlorothiazide: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

• a light-headed feeling, like you might pass out;
• eye pain, vision problems;
• jaundice (yellowing of the skin or eyes);
• pale skin, easy bruising, unusual bleeding (nose, mouth, vagina, or rectum);
• shortness of breath, wheezing, cough with foamy mucus, chest pain;
• signs of electrolyte imbalance--dry mouth, thirst, drowsiness, lack of energy, restlessness, muscle pain or weakness, fast heart rate, nausea and vomiting, little or no urine; or
• severe skin reaction--fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Common hydrochlorothiazide side effects may include:

• nausea, vomiting, loss of appetite;
• diarrhea, constipation;
• muscle spasm; or
• dizziness, headache.

This is not a complete list of side effects and others may occur. 

What other drugs will affect hydrochlorothiazide?

Taking this medicine with other drugs that make you light-headed can worsen this effect. Ask your doctor before taking a sleeping pill, narcotic pain medicine, muscle relaxer, or medicine for anxiety, depression, or seizures.

Tell your doctor about all your current medicines and any you start or stop using, especially:

• cholestyramine, colestipol;
• insulin or oral diabetes medicine;
• lithium;
• other blood pressure medications;
• steroid medicine; or
• NSAIDs (nonsteroidal anti-inflammatory drugs)--aspirin, ibuprofen (Advil, Motrin), naproxen (Aleve), celecoxib, diclofenac, indomethacin, meloxicam, and others.

This list is not complete. Other drugs may interact with hydrochlorothiazide, including prescription and over-the-counter medicines, vitamins, and herbal products. 

References:

https://www.webmd.com/drugs/2/drug-5310/hydrochlorothiazide-oral/details

https://www.drugs.com/hydrochlorothiazide.html

https://www.healthline.com/health/hydrochlorothiazide-oral-tablet

https://www.mayoclinic.org/drugs-supplements/hydrochlorothiazide-oral-route/description/drg-20071841

https://medlineplus.gov/druginfo/meds/a682571.html

https://www.cardiosmart.org/Healthwise/d002/53/d00253