HCTZ

HCTZ is a medication that is prescribed for the treatment of fluid retention and high blood pressure. By increasing the amount of salt and water that the kidneys remove from the blood and decreasing blood volume, the medication can effectively control high blood pressure and help with water retention. HCTZ is sold under a variety of brand names and is also available as a generic medicine. Possible side effects of the drug may include upset stomach, dizziness, vomiting, or low blood potassium levels.

 

What Is HCTZ?

HCTZ (hydrochlorothiazide or HCT) is a prescription medicine that is used to treat high blood pressure and fluid retention. It is part of a class of medicines known as diuretics.
 
The drug is sold under a number of brand names, including Esidrix®, HydroDIURIL®, Microzide®, and Oretic®. It is also available as a generic. HCTZ is sometimes referred to as hydrochlorothiazide (or just HCT).
 
HCTZ may be used in children and infants with high blood pressure or fluid retention, although it has not been thoroughly studied for this age group. Be sure to talk to your healthcare provider about the benefits and risks of using hydrochlorothiazide in children and infants.
 

Who Makes HCTZ?

Several manufacturers make brand-name HCTZ. Generic HCTZ is also made by multiple generic manufacturers.
 

What Is It Used For?

Specific uses of HCTZ include:
 
 

 

(Click HCTZ Uses for more information on what it is used for, including possible off-label uses.)
 

How Does It Work?

HCTZ is a diuretic, which is commonly referred to as a "water pill." It works by increasing the amount of salt and water that the kidneys remove from the blood. This extra salt and water is passed out through the urine. By increasing the amount of water removed from the blood, HCTZ causes a decrease in blood volume. Because of this effect, HCTZ can lower blood pressure and help with water retention.
 

Effects

A blood pressure reading consists of two numbers -- for example: 120/80. The top number is known as the systolic blood pressure, and the bottom number is the diastolic blood pressure. During clinical studies in people taking HCTZ, both systolic and diastolic blood pressure decreased significantly.
 
By lowering blood pressure, HCTZ can decrease the risk of developing health problems, such as a heart attack or stroke, that can occur as a result of long-term high blood pressure (see Effects of High Blood Pressure).
 

When and How to Take HCTZ

Some general considerations for when and how to take the medication include:
 
  • HCTZ comes in tablet and capsule form. It is usually taken by mouth once a day, although it may be taken several times a day.
     
  • You can take it with or without food.
     
  • If necessary, HCTZ tablets (but not capsules) may be split in half.
     
  • The medication should be taken at the same time each day to maintain an even level of medicine in your blood. However, some people do not need to take it every day, especially those who are taking it for fluid retention.
     
  • Because HCTZ increases urination, it is best to take it in the morning (to avoid needing to get up to use the bathroom throughout the night). If you take HCTZ multiple times per day, it is best to take the last dose of the day before 6 PM (unless you are instructed otherwise).
     
  • For HCTZ to work properly, you have to take it as prescribed; it will not work if you stop taking it.
     

Dosing

The dose of HCTZ that your healthcare provider recommends will vary depending on a number of factors, including:
 
  • Other medical conditions you may have
  • Other medications you may be currently taking
  • How you respond to HCTZ.
     
As with any medication, do not adjust your dose unless your healthcare provider specifically instructs you to do so.
 
(Click HCTZ Dosage for more information.)
 

Side Effects

As with any medicine, there are possible side effects with HCTZ. However, not everyone who takes the medication will experience side effects. When they do occur, side effects are often minor, meaning that they require no treatment or are easily treated by you or your healthcare provider. Serious side effects are less common.
 
The most common HCTZ side effects seen in people with high blood pressure include:
 
  • Low blood potassium levels (hypokalemia) or other electrolyte imbalances
  • Dizziness
  • Upset stomach (nausea) or vomiting.
     
(Click HCTZ Side Effects to learn about the specific side effects of this drug, including serious side effects to look out for.)
 
You can also read about other possible side effects by going to the following eMedTV articles:
 

Drug Interactions

HCTZ can potentially interact with a number of medicines.
 
(Click Drug Interactions With HCTZ for more information.)
 

What Should I Tell My Healthcare Provider?

You should talk with your healthcare provider prior to taking this medication if you have:
 
  • Liver disease, including cirrhosis
  • Kidney disease or kidney failure
  • Diabetes
  • Systemic lupus erythematosus (lupus or SLE)
  • A personal or family history of angioedema, which is swelling under the skin (especially of the throat or mouth)
  • Gout
  • Pancreatitis
  • High cholesterol
  • Allergies
  • Asthma
  • Fluid or electrolyte problems
  • Parathyroid problems
  • Had a sympathectomy (a specific kind of surgery)
  • Any allergies, including allergies to HCTZ, ACE inhibitors, sulfa drugs, foods, dyes, or preservatives.
     
Also, let your healthcare provider know if you:
 
Tell your healthcare provider about all other medicines you may currently be taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
 
(Click Precautions and Warnings With HCTZ for more information on this topic, including information on who should not take the drug.)
 

Overdose With HCTZ

People who take too much HCTZ may have overdose symptoms that could include:
 
  • Low blood pressure (hypotension)
  • Low electrolytes (especially low potassium, chloride, and sodium).
     
If you happen to overdose on HCTZ, seek medical attention immediately.
 
(Click Hydrochlorothiazide Overdose for more information.)
 

Storage Methods

HCTZ should be stored at room temperature, away from moisture and heat. HCTZ tablets and capsules should be kept in an airtight container.
 
Keep HCTZ and all medications out of the reach of children.
 

What Should I Do If I Miss a Dose?

If you do not take your HCTZ as scheduled, take your next dose as soon as you remember. If it is almost time for your next scheduled dose, skip the missed one and continue with normal dosing. Do not take a double dose.
 

Strengths

HCTZ is available in the following strengths:
 
  • HCTZ 12.5 mg capsules
  • HCTZ 25 mg tablets
  • HCTZ 50 mg tablets.
     

Generic HCTZ

Currently, there are both brand-name and generic HCTZ licensed for sale.
 
(Click Generic HCTZ for more information.)
 
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;