Uses

What is hydrochlorothiazide used for?

Hydrochlorothiazide is commonly used to treat high blood pressure (hypertension).

Hydrochlorothiazide is a diuretic, also called a water pill, that may be used to reduce edema (fluid retention) caused by the following conditions.

  • Congestive heart failure, which is a condition where the heart is not pumping as well as it should
  • Liver disease, such as cirrhosis, which can lead to a buildup of fluid in the abdomen (ascites)
  • Kidney disease, including protein in the urine (nephrotic syndrome)
  • Fluid caused by the use of hormones, such as estrogen or other steroids

Hydrochlorothiazide may also be used for other conditions as determined by your healthcare provider.

How does hydrochlorothiazide work (mechanism of action)?

Hydrochlorothiazide works by increasing how much you pee. It does this by helping the kidneys remove electrolytes, such as sodium (salt), and water from the body.  It also appears to allow blood to flow more freely (less resistance to flow), which may help with lowering blood pressure.

How is hydrochlorothiazide supplied (dosage forms)?

Hydrochlorothiazide is available as Microzide and generic hydrochlorothiazide in the following dosage forms that are taken by mouth.

  • 12.5 mg oral capsules
  • 12.5 mg oral tablets
  • 25 mg oral tablets
  • 50 mg oral tablets

How should I store hydrochlorothiazide?

Hydrochlorothiazide should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C), for shorter periods of time, such as when transporting it. Store in a cool, dry place. Keep tightly closed.

Side Effects

What are the most common side effects of hydrochlorothiazide?

The most common side effects of hydrochlorothiazide are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Low blood pressure (see below)
  • Electrolyte changes and increased blood sugar (see below)
  • An increase in how much you pee

There may be other side effects of hydrochlorothiazide that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of hydrochlorothiazide?

While less common, the most serious side effects of hydrochlorothiazide are described below, along with what to do if they happen.

Low Blood Pressure with Worsening Kidney Function. Water loss from hydrochlorothiazide can lower your blood pressure too much and cause dehydration.  Both may lead to problems that are more serious than light-headedness. Poor blood flow to important organs such as your kidneys can occur, especially if you are elderly. Drink enough water to stay hydrated, especially if you have excess sweating, vomiting, or diarrhea. Get out of bed or from a seated position slowly. Tell your healthcare provider right away if you have any of the following symptoms.

  • Dizziness, feeling lightheaded, or fainting
  • Confusion
  • Feeling weak or tired
  • Sudden weight gain
  • Confusion
  • Reduced need to pee
  • Increased thirst
  • Dark or strong-smelling pee
  • Dry mouth
  • Sunken eyes
  • Headache
  • Fast heartbeat

Electrolyte Changes and Increased Blood Sugar. Hydrochlorothiazide may increase your blood sugar (glucose) levels and cause changes to the levels of certain minerals in your body, called electrolytes. For example, it may cause low potassium levels (hypokalemia), low sodium levels (hyponatremia), low magnesium levels (hypomagnesemia), high calcium levels (hypercalcemia), or low chloride levels (hypochloremia), or high glucose levels (hyperglycemia). These changes can be serious. Your healthcare provider will do bloodwork to check your glucose and electrolyte levels, especially if you take certain other medicines. Keep your appointments to have your blood checked. Call your healthcare provider if you have any of the following symptoms.

  • Weakness
  • Unusual tiredness
  • Muscle cramps or twitching
  • Constipation
  • Nausea, vomiting, or loss of appetite
  • Dizziness
  • Restlessness or irritability
  • Difficulty breathing
  • Confusion or decreased alertness
  • Abnormal heart rhythm
  • Seizures

Short-Sightedness and Glaucoma. Hydrochlorothiazide may make it harder to see faraway objects (short-sightedness). It also may increase pressure inside the eye and cause or worsen narrow-angle glaucoma, which can lead to blindness. These issues may be more likely with taking hydrochlorothiazide if you have a sulfa or penicillin allergy. Tell your healthcare provider right away if you have any of the following symptoms.

  • Trouble seeing faraway objects
  • Loss of vision
  • Eye pain or redness
  • Severe headache or vomiting
  • Seeing bright, colorful circles around lights (vision halos)

Severe Allergic Reactions. Hydrochlorothiazide may cause allergic reactions, which can be serious. Stop using hydrochlorothiazide and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Severe Skin Reactions. Hydrochlorothiazide can cause severe skin reactions called Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) that can lead to death if not treated. If you develop a rash, stop hydrochlorothiazide and call your healthcare provider right away. Get emergency help right away if you have any of the following symptoms of SJS or TEN.

  • Painful red or purple skin that looks burned and peels off
  • Flat red rash or blisters on your skin, mouth, nose, and genitals
  • Red, painful, watery eyes

Inflammation of the Pancreas (Pancreatitis). Hydrochlorothiazide may cause inflammation of the pancreas, which is called pancreatitis. Stop taking hydrochlorothiazide and call your healthcare provider right away if you have symptoms of pancreatitis, including vomiting or severe pain in the upper part of your belly that travels to your back.

Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking hydrochlorothiazide. Call your healthcare provider right away if you have any of the following symptoms of liver damage.

  • Nausea or vomiting
  • Stomach or belly pain
  • Fever
  • Weakness or unusual tiredness
  • Itching
  • Loss of appetite
  • Light-colored poop
  • Dark-colored urine

Warnings & Precautions

Who should not use hydrochlorothiazide?

Allergies to Ingredients. People who are allergic to any of the following should not use hydrochlorothiazide.

  • Hydrochlorothiazide
  • Esidrix
  • HydroDiuril
  • Microzide
  • Oretic
  • Zide
  • Any other medicine known as a sulfonamide (sulfa drug)
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific hydrochlorothiazide products they stock.

No Urine Production. Do not take hydrochlorothiazide if you are making very little to no pee.  This condition is also called anuria.

Very Low Electrolytes. If you have low electrolytes, including low sodium or potassium, hydrochlorothiazide may not be safe to use. Your healthcare provider may measure your electrolytes before starting hydrochlorothiazide.  Low electrolytes are not usually something you can feel, so it is important to make it to your scheduled blood work appointments.

What should I know about hydrochlorothiazide before using it?

Do not take hydrochlorothiazide unless it has been prescribed to you by a healthcare provider. Take it as prescribed.

Do not share hydrochlorothiazide with other people, even if they have the same condition as you. It may harm them.

Keep hydrochlorothiazide out of the reach of children.

Hydrochlorothiazide can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how hydrochlorothiazide affects you. 

People who are age 65 or older can be at greater risk for some side effects from hydrochlorothiazide. Talk to your healthcare provider about your risks if you are in this age group.

Your skin may be very sensitive to light from the sun and devices that give off similar light, such as sunlamps and tanning beds, while you are taking certain drugs, including hydrochlorothiazide. This is called photosensitivity. Use sunscreen and wear a hat and clothes that cover your skin if you need to be in the sunlight. Talk to your healthcare provider about checkups for skin cancer.


What should I tell my healthcare provider before using hydrochlorothiazide?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if hydrochlorothiazide is right for you.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.

  • Heart failure
  • Liver problems
  • Kidney problems
  • Persistent or severe diarrhea or vomiting, which can lead to dehydration
  • Low electrolytes, including potassium and sodium
  • Abnormal heart rhythm (arrhythmias)
  • Diabetes
  • Gout
  • Prostate problems
  • A reduced need to pee

Systemic Lupus Erythematosus. Hydrochlorothiazide may activate or worsen systemic lupus erythematosus. Tell your healthcare provider if you develop or have worsening rash, joint pain, fever, or unusual tiredness.

Sulfa Allergy. Some people who have a sulfa allergy may also be allergic to hydrochlorothiazide. A sulfa allergy is a rash or more serious reaction to sulfa, or sulfonamide, medicines. Sulfa medicines include sulfamethoxazole, sulfadiazine silver, or sulfasalazine. Tell your healthcare provider if you have any allergies to medicines.

Other Medicines and Supplements. Hydrochlorothiazide may interact with other medicines and supplements. Before using hydrochlorothiazide, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how hydrochlorothiazide could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. Your healthcare provider will advise you if you should take hydrochlorothiazide while you are pregnant or trying to get pregnant.

Breastfeeding. Do not take hydrochlorothiazide while you are breastfeeding. Hydrochlorothiazide can pass into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed.

Interactions

Does hydrochlorothiazide interact with foods or drinks?

There are no known interactions between hydrochlorothiazide and foods or drinks. However, since hydrochlorothiazide affects electrolytes, it is important to discuss your intake of electrolytes, including sodium and potassium, with your healthcare provider.

It is unknown if drinking alcohol will affect hydrochlorothiazide. The risk of dizziness may be increased if you drink alcohol while taking hydrochlorothiazide. It is best to limit the amount of alcohol you drink.

Does hydrochlorothiazide interact with other medicines (drug interactions)?

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before using hydrochlorothiazide.

  • A barbiturate, such as phenobarbital, butalbital, or primidone, which is a medicine that may be used to treat insomnia, migraines, or seizures
  • An opioid, such as oxycodone, morphine, codeine, or fentanyl, which is a medicine used for certain types of pain
  • A medicine for diabetes
  • A medicine for high blood pressure
  • Cholestyramine or colestipol, which are sometimes used to lower cholesterol
  • A corticosteroid, such as prednisone, methylprednisolone, or dexamethasone, which is a medicine for certain inflammatory conditions
  • Lithium, which is a medicine commonly used for certain mental health conditions
  • A nonsteroidal anti-inflammatory drug (NSAID), such as ibuprofen, naproxen, and others, which are contained in many prescription and OTC products for pain, swelling, and fever
  • Digoxin (Lanoxin), which is a medicine used to treat irregular heartbeat and some types of heart failure
  • A diuretic, also called a water pill, which is a medicine used to reduce edema (fluid retention) and blood pressure

Does Hydrochlorothiazide interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much hydrochlorothiazide?

If you or someone else has used too much hydrochlorothiazide, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of hydrochlorothiazide?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.

You Might Also Like

Drug Survey

Are you currently using Hydrochlorothiazide?

This survey is being conducted by the WebMD marketing sciences department.