Hydrochlorothiazide: Indications, How to Take, Dosing & Side Effects

Hydrochlorothiazide is a prescription diuretic medication primarily used to treat high blood pressure and swelling associated with conditions like congestive heart failure and liver cirrhosis. It functions by helping the kidneys eliminate excess salt and fluid from the body, which effectively lowers blood pressure and reduces fluid retention.

This medication is typically available in 25 mg or 50 mg tablets and is sold as a generic drug or under the brand name Microzide. It requires a doctor's prescription and is frequently prescribed alongside other medications to maximize its effectiveness in managing hypertension.

Physicians may combine hydrochlorothiazide with other active ingredients, such as olmesartan, losartan, valsartan, or irbesartan, to provide better blood pressure control. These combination therapies are often used when a single medication is not sufficient to reach blood pressure goals.

What it is for

Hydrochlorothiazide is indicated for the treatment of:

• High blood pressure (hypertension)

• Ascites caused by liver cirrhosis

• Congestive heart failure

• Nephrotic syndrome

• Acute glomerulonephritis

• Chronic kidney failure

Additionally, hydrochlorothiazide may be used to treat fluid retention caused by other medications, such as corticosteroids or estrogens.

The drug works by increasing the amount of salt eliminated through urine. As salt is removed, it draws water from the blood with it, decreasing the volume of fluid in the veins and arteries. This process helps lower high blood pressure and reduce swelling.

Does hydrochlorothiazide cause weight loss?

Hydrochlorothiazide does not cause true weight loss, as it has no effect on burning calories or reducing body fat. However, patients may notice a decrease in weight shortly after starting treatment due to the elimination of excess fluids accumulated in the body.

It is important to emphasize that hydrochlorothiazide is not indicated for weight loss purposes. To lose weight safely, you should consult an endocrinologist or primary care provider who can recommend an appropriate diet, physical activity, weight loss medications, or bariatric surgery.

How to take

Hydrochlorothiazide should be taken orally with a glass of water, either before or after a meal, strictly following the schedule established by your doctor.

The dosage varies depending on the condition being treated and whether it is taken alone or in combination with other drugs. Common dosages include:

1. Hydrochlorothiazide 25 mg

The 25 mg tablet, as well as the 50 mg tablet, can be prescribed for adults or children based on medical recommendations. Dosages for adults vary by condition:

High blood pressure

• Dosage: 50 to 100 mg per day, taken as a single dose or divided into two doses.

• This dose may be adjusted by a cardiologist until blood pressure is adequately controlled.

Swelling (edema)

• Initial dose: 50 to 100 mg, taken once or twice daily.

• Maintenance dose: 25 to 200 mg per day, taken daily or on alternate days.

For children, the pediatrician must calculate the dose based on weight. A common range is 2 to 3 mg per kg of body weight per day, divided into two doses.

During treatment, blood pressure should be measured at least once a day and recorded to share with the doctor during appointments, allowing for necessary dosage adjustments.

2. Olmesartan medoxomil + hydrochlorothiazide

Combination tablets containing olmesartan medoxomil and hydrochlorothiazide (such as Benicar HCT) are available in strengths of 20 mg or 40 mg of olmesartan combined with 12.5 mg or 25 mg of hydrochlorothiazide.

• Dosage: The recommended adult dose for high blood pressure is one tablet taken once daily.

• Adjustment: The specific strength prescribed should be determined by a cardiologist based on blood pressure levels and treatment response.

3. Losartan + hydrochlorothiazide

Combination tablets containing 50 mg of losartan and 12.5 mg of hydrochlorothiazide (such as Hyzaar) are indicated for adults treating high blood pressure.

• Dosage: The recommended dose is one tablet taken once daily.

• Adjustment: A doctor may increase this dose to up to two tablets per day, depending on how the patient responds to treatment.

4. Valsartan + hydrochlorothiazide

Tablets combining valsartan and hydrochlorothiazide (such as Diovan HCT) are available with 80 mg, 160 mg, or 320 mg of valsartan combined with 12.5 mg or 25 mg of hydrochlorothiazide.

• Dosage: The recommended adult dose for high blood pressure is one tablet taken once daily.

• Adjustment: The specific strength required should be determined by a cardiologist based on blood pressure readings.

Possible side effects

The most common side effects of hydrochlorothiazide include:

• Excessive weakness

• Dizziness

• Pain in the upper stomach area

• Nausea or vomiting

• Chills or cold hands and feet

• Bleeding or bruising easily

Hydrochlorothiazide can also cause severe allergic reactions or anaphylaxis, which require immediate emergency medical attention.

Additionally, notify a doctor if symptoms of dehydration occur, such as extreme thirst, feeling very hot, difficulty urinating, heavy sweating, confusion, leg cramps, irregular heartbeat, or tingling in the arms or legs.

Who should not use

Hydrochlorothiazide should not be used by women who are pregnant or breastfeeding. It is also contraindicated for people with liver disease, severe kidney failure, glaucoma, asthma, gout, or those unable to urinate (anuria).

People with allergies to hydrochlorothiazide or sulfonamide-derived antibiotics (sulfa drugs) should not use this medication.

It should be used with caution or avoided by individuals with diabetes, as it can raise blood glucose levels and cause glycosuria (sugar in the urine). Because it increases blood sugar, it may interfere with the effectiveness of diabetes medications; dose adjustments may be necessary under medical guidance.

Hydrochlorothiazide may also trigger diabetes in people with prediabetes. Therefore, it should be used carefully in anyone with glucose intolerance or a predisposition to hyperglycemia.