Hydrochlorothiazide, USP | indications and side effects

Hydrochlorothiazide, USP | indications and side effects

Hydrochlorothiazide is a diuretic and antihypertensive. It is the 3, 4-dihydro derivative of chlorothiazide. It is chemically designated as 6chloro-3, 4-dihydro-2 H-1, 2, 4-benzothiadiazine-7-sulfonamide 1, 1-dioxide

Hydrochlorothiazide, USP is a white, or practically white, crystalline powder which is slightly soluble in water, freely soluble in sodium hydroxide solution, in n-butylamine, and in dimethylformamide; sparingly soluble in methanol; insoluble in ether, in chloroform, and in dilute mineral acids. Each tablet for oral administration contains 12.5 mg, 25 mg or 50 mg hydrochlorothiazide, USP. In addition, each tablet contains the following inactive ingredients: colloidal silicon dioxide, magnesium stearate, microcrystalline cellulose, pre-gelatinized starch, and sodium lauryl sulfate.


Hydrochlorothiazide is a thiazide-type diuretic chiefly used as an antihypertension agent for the control of elevated blood pressure. It is often combined with other agents in the treatment of hypertension, either through separate prescriptions for hydrochlorothiazide and the other agents, or through the use of combination products in which a single tablet contains hydrochlorothiazide plus one other antihypertensive medication (more rarely, two other agents).

In the USA, hydrochlorothiazide is indicated for “the management of hypertension either as the sole therapeutic agent or in combination with other antihypertensives” and is recommended as first-line medication (Chobanian et al., 2003). The Food and Drug Administration thirty-four combinations containing two agents, and four combinations containing three agents, although not all of these forms were currently available (FDA, 2013).

The most common drugs combined with hydrochlorothiazide are triamterene (see Monograph on triamterene in this volume), lisinopril, losartan, and valsartan (IMS Health, 2012a).

The European Medicines Agency indication for hydrochlorothiazide is “for treatment of hypertension”. Labelling includes use for hypertension and oedema for combination drugs containing hydrochlorothiazide and another diuretic agent. Hydrochlorothiazide is a recommended drug in Europe (Mansia et al., 2007, 2009).

Although hydrochlorothiazide is a registered product, it is generally available only in combination products. The European Union listed nineteen combination products containing hydrochlorothiazide and one other drug, and two containing two other agents, although not all are currently in use (eMC, 2013).

What does Hydrochlorothiazide do?

• It is a “water pill” used to treat high blood pressure and re move extra fluid in the body

How should Hydrochlorothiazide be used?

• Take this medicine as directed by your doctor

• It is taken one (1) time a day. Take this medicine at the same time every day

• Take with or without food

• It is best to take this medicine in the morning to avoid going to the bathroom during the night


Edema (diuresis): 25-100 mg/day in 1-2 doses; maximum: 200 mg/day

Hypertension: Oral: 12.5-50 mg/day; minimal increase in response and more electrolyte disturbances are seen with doses greater than 50 mg/day,

Geriatric Oral: 12.5-25 mg once daily; minimal increase in response and more electrolyte disturbances are seen with doses greater than 50 mg/day.

Use in Pregnancy:

 Routine use of diuretics during normal pregnancy is inappropriate and exposes mother and fetus to unnecessary hazard. Diuretics do not prevent development of toxemia of pregnancy and there is no satisfactory evidence that they are useful in the treatment of toxemia.

Edema during pregnancy may arise from pathologic causes or from the physiologic and mechanical consequences of pregnancy. Thiazides are indicated in pregnancy when edema is due to pathologic causes, just as they are in the absence of pregnancy

Dependent edema in pregnancy, resulting from restriction of venous return by the gravid uterus, is properly treated through elevation of the lower extremities and use of support stockings. Use of diuretics to lower intravascular volume in this instance is illogical and unnecessary. During normal pregnancy there is hypervolemia which is not harmful to the fetus or the mother in the absence of cardiovascular disease.

However, it may be associated with edema, rarely generalized edema. If such edema causes discomfort, increased recumbence will often provide relief. Rarely this edema may cause extreme discomfort which is not relieved by rest. In these instances, a short course of diuretic therapy may provide relief and be appropriate.

What side effects could occur with Hydrochlorothiazide?

• Feeling dizzy

• Dry mouth, upset stomach, or throwing up

• Signs of low potassium such as: muscle pain or weakness; muscle cramps; or a heartbeat that does not feel normal

Dihydrochlorothiazid; Dihydrochlorothiazide; Dihydrochlorothiazidum; Dihydrochlorurit; Dihydrochlorurite; Dihydroxychlorothiazidum; HCTZ; HCZ; Hydrochlorothiazid; Hydrochlorthiazide (DrugBank, 2013); Hidroclorotiazida; Hydrochlorothiazidum; Chlorsulfonamidodihydrobenzothiadiazine dioxide; Chlorosulthiadil; 3,4-dihydrochlorothiazide (IPCS, 2013) WHO International Nonproprietary Name (INN): Hydrochlorothiazidum (WHO, 2006)

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