Hydrochlorothiazide

Hydrochlorothiazide is used for the treatment of high blood pressure and fluid retention. It is a type of diuretic that works by increasing the amount of salt and water that the kidneys remove from the blood, which causes a decrease in blood volume. Hydrochlorothiazide comes in both capsule and tablet form and is available in a number of strengths. Potential side effects of the medication may include low blood potassium levels, dizziness, upset stomach, and vomiting.

 

What Is Hydrochlorothiazide?

Hydrochlorothiazide (HCTZ) 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.
 
Hydrochlorothiazide is sold under a number of brand names, including Esidrix®, HydroDIURIL®, Microzide®, and Oretic®. It is also available as a generic. The medication is sometimes referred to as HCTZ or HCT for short.
 
It 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 Hydrochlorothiazide?

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

What Is It Used For?

Specific uses of hydrochlorothiazide include:
 
 

 

(Click What Is Hydrochlorothiazide Used For? for more information, including possible off-label uses.)
 

How Does It Work?

Hydrochlorothiazide 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, hydrochlorothiazide causes a decrease in blood volume. Because of this effect, the drug can lower blood pressure and help with water retention.
 

Effects of Hydrochlorothiazide

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 hydrochlorothiazide, both systolic and diastolic blood pressure decreased significantly.
 
By lowering blood pressure, the medication 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 Do I Take It?

Some general considerations for when and how to take hydrochlorothiazide include:
 
  • The medication 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, hydrochlorothiazide tablets (but not capsules) may be split in half.
     
  • It 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 hydrochlorothiazide 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 it multiple times per day, it is best to the take the last dose of the day before 6 PM (unless you are instructed otherwise).
     
  • For the medication to work properly, you have to take it as prescribed; it will not work if you stop taking it.
     

Dosage Information

The dosage 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 hydrochlorothiazide.
     
As with any medication, do not adjust your dose unless your healthcare provider specifically instructs you to do so.
 
(Click Hydrochlorothiazide Dosing for more information.)
 

Side Effects

As with any medicine, there are possible side effects with this medication. However, not everyone who takes it 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 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 Side Effects of Hydrochlorothiazide to learn about specific side effects of the 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 With Hydrochlorothiazide

Hydrochlorothiazide can potentially interact with a number of medicines.
 
(Click Hydrochlorothiazide Drug Interactions for more information about these possible interactions.)
 

What Should I Tell My Healthcare Provider?

Prior to taking hydrochlorothiazide, you should talk with your healthcare provider 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 hydrochlorothiazide, 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 Hydrochlorothiazide Warnings and Precautions for more information on this topic, including information on who should not take hydrochlorothiazide.)
 

Overdose With Hydrochlorothiazide

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

Storage Methods

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

What Should I Do If I Miss a Dose?

If you do not take your hydrochlorothiazide 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 of Hydrochlorothiazide

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

Generic Hydrochlorothiazide

Currently, there are both brand-name and generic versions of hydrochlorothiazide licensed for sale.
 
(Click Generic Hydrochlorothiazide for more information.)
 
Add this article to your Favorites     Email this article     Print
Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;